diff options
| -rwxr-xr-x | cmd/arc_summary/arc_summary.py | 4 | ||||
| -rwxr-xr-x | cmd/arcstat/arcstat.py | 2 | ||||
| -rw-r--r-- | include/sys/Makefile.am | 2 | ||||
| -rw-r--r-- | include/sys/arc.h | 9 | ||||
| -rw-r--r-- | include/sys/arc_impl.h | 22 | ||||
| -rw-r--r-- | include/sys/multilist.h | 105 | ||||
| -rw-r--r-- | include/sys/trace_multilist.h | 76 | ||||
| -rw-r--r-- | include/sys/zfs_context.h | 1 | ||||
| -rw-r--r-- | lib/libzpool/Makefile.am | 1 | ||||
| -rw-r--r-- | man/man5/zfs-module-parameters.5 | 60 | ||||
| -rw-r--r-- | module/zfs/Makefile.in | 1 | ||||
| -rw-r--r-- | module/zfs/arc.c | 1859 | ||||
| -rw-r--r-- | module/zfs/dbuf_stats.c | 7 | ||||
| -rw-r--r-- | module/zfs/dsl_pool.c | 9 | ||||
| -rw-r--r-- | module/zfs/multilist.c | 375 | ||||
| -rw-r--r-- | module/zfs/trace.c | 3 | ||||
| -rw-r--r-- | module/zfs/zio_inject.c | 6 |
17 files changed, 1862 insertions, 680 deletions
diff --git a/cmd/arc_summary/arc_summary.py b/cmd/arc_summary/arc_summary.py index 15d844b52..25238f39e 100755 --- a/cmd/arc_summary/arc_summary.py +++ b/cmd/arc_summary/arc_summary.py @@ -191,12 +191,10 @@ def get_arc_summary(Kstat): ### ARC Misc. ### deleted = Kstat["kstat.zfs.misc.arcstats.deleted"] mutex_miss = Kstat["kstat.zfs.misc.arcstats.mutex_miss"] - recycle_miss = Kstat["kstat.zfs.misc.arcstats.recycle_miss"] ### ARC Misc. ### output["arc_misc"] = {} output["arc_misc"]["deleted"] = fHits(deleted) - output["arc_misc"]['recycle_miss'] = fHits(recycle_miss) output["arc_misc"]['mutex_miss'] = fHits(mutex_miss) output["arc_misc"]['evict_skips'] = fHits(mutex_miss) @@ -302,8 +300,6 @@ def _arc_summary(Kstat): ### ARC Misc. ### sys.stdout.write("ARC Misc:\n") sys.stdout.write("\tDeleted:\t\t\t\t%s\n" % arc['arc_misc']['deleted']) - sys.stdout.write("\tRecycle Misses:\t\t\t\t%s\n" % - arc['arc_misc']['recycle_miss']) sys.stdout.write("\tMutex Misses:\t\t\t\t%s\n" % arc['arc_misc']['mutex_miss']) sys.stdout.write("\tEvict Skips:\t\t\t\t%s\n" % diff --git a/cmd/arcstat/arcstat.py b/cmd/arcstat/arcstat.py index b516cf285..bbf43100a 100755 --- a/cmd/arcstat/arcstat.py +++ b/cmd/arcstat/arcstat.py @@ -82,7 +82,6 @@ cols = { "mrug": [4, 1000, "MRU Ghost List hits per second"], "eskip": [5, 1000, "evict_skip per second"], "mtxmis": [6, 1000, "mutex_miss per second"], - "rmis": [4, 1000, "recycle_miss per second"], "dread": [5, 1000, "Demand accesses per second"], "pread": [5, 1000, "Prefetch accesses per second"], "l2hits": [6, 1000, "L2ARC hits per second"], @@ -406,7 +405,6 @@ def calculate(): v["mrug"] = d["mru_ghost_hits"] / sint v["mfug"] = d["mfu_ghost_hits"] / sint v["eskip"] = d["evict_skip"] / sint - v["rmis"] = d["recycle_miss"] / sint v["mtxmis"] = d["mutex_miss"] / sint if l2exist: diff --git a/include/sys/Makefile.am b/include/sys/Makefile.am index 5211e6564..fd80b34ee 100644 --- a/include/sys/Makefile.am +++ b/include/sys/Makefile.am @@ -33,6 +33,7 @@ COMMON_H = \ $(top_srcdir)/include/sys/efi_partition.h \ $(top_srcdir)/include/sys/metaslab.h \ $(top_srcdir)/include/sys/metaslab_impl.h \ + $(top_srcdir)/include/sys/multilist.h \ $(top_srcdir)/include/sys/nvpair.h \ $(top_srcdir)/include/sys/nvpair_impl.h \ $(top_srcdir)/include/sys/range_tree.h \ @@ -53,6 +54,7 @@ COMMON_H = \ $(top_srcdir)/include/sys/trace_dbuf.h \ $(top_srcdir)/include/sys/trace_dmu.h \ $(top_srcdir)/include/sys/trace_dnode.h \ + $(top_srcdir)/include/sys/trace_multilist.h \ $(top_srcdir)/include/sys/trace_txg.h \ $(top_srcdir)/include/sys/trace_zil.h \ $(top_srcdir)/include/sys/trace_zrlock.h \ diff --git a/include/sys/arc.h b/include/sys/arc.h index 903f0b413..38f9f27fe 100644 --- a/include/sys/arc.h +++ b/include/sys/arc.h @@ -38,6 +38,12 @@ extern "C" { #include <sys/spa.h> #include <sys/refcount.h> +/* + * Used by arc_flush() to inform arc_evict_state() that it should evict + * all available buffers from the arc state being passed in. + */ +#define ARC_EVICT_ALL -1ULL + typedef struct arc_buf_hdr arc_buf_hdr_t; typedef struct arc_buf arc_buf_t; typedef struct arc_prune arc_prune_t; @@ -146,7 +152,6 @@ typedef enum arc_state_type { typedef struct arc_buf_info { arc_state_type_t abi_state_type; arc_buf_contents_t abi_state_contents; - uint64_t abi_state_index; uint32_t abi_flags; uint32_t abi_datacnt; uint64_t abi_size; @@ -200,7 +205,7 @@ void arc_freed(spa_t *spa, const blkptr_t *bp); void arc_set_callback(arc_buf_t *buf, arc_evict_func_t *func, void *private); boolean_t arc_clear_callback(arc_buf_t *buf); -void arc_flush(spa_t *spa); +void arc_flush(spa_t *spa, boolean_t retry); void arc_tempreserve_clear(uint64_t reserve); int arc_tempreserve_space(uint64_t reserve, uint64_t txg); diff --git a/include/sys/arc_impl.h b/include/sys/arc_impl.h index 556cc2583..54f5e9f40 100644 --- a/include/sys/arc_impl.h +++ b/include/sys/arc_impl.h @@ -67,10 +67,22 @@ extern "C" { */ typedef struct arc_state { - list_t arcs_list[ARC_BUFC_NUMTYPES]; /* list of evictable buffers */ - uint64_t arcs_lsize[ARC_BUFC_NUMTYPES]; /* amount of evictable data */ - uint64_t arcs_size; /* total amount of data in this state */ - kmutex_t arcs_mtx; + /* + * list of evictable buffers + */ + multilist_t arcs_list[ARC_BUFC_NUMTYPES]; + /* + * total amount of evictable data in this state + */ + uint64_t arcs_lsize[ARC_BUFC_NUMTYPES]; + /* + * total amount of data in this state; this includes: evictable, + * non-evictable, ARC_BUFC_DATA, and ARC_BUFC_METADATA. + */ + uint64_t arcs_size; + /* + * supports the "dbufs" kstat + */ arc_state_type_t arcs_state; } arc_state_t; @@ -136,7 +148,7 @@ typedef struct l1arc_buf_hdr { /* protected by arc state mutex */ arc_state_t *b_state; - list_node_t b_arc_node; + multilist_node_t b_arc_node; /* updated atomically */ clock_t b_arc_access; diff --git a/include/sys/multilist.h b/include/sys/multilist.h new file mode 100644 index 000000000..98d707dd7 --- /dev/null +++ b/include/sys/multilist.h @@ -0,0 +1,105 @@ +/* + * CDDL HEADER START + * + * This file and its contents are supplied under the terms of the + * Common Development and Distribution License ("CDDL"), version 1.0. + * You may only use this file in accordance with the terms of version + * 1.0 of the CDDL. + * + * A full copy of the text of the CDDL should have accompanied this + * source. A copy of the CDDL is also available via the Internet at + * http://www.illumos.org/license/CDDL. + * + * CDDL HEADER END + */ +/* + * Copyright (c) 2013, 2014 by Delphix. All rights reserved. + */ + +#ifndef _SYS_MULTILIST_H +#define _SYS_MULTILIST_H + +#include <sys/zfs_context.h> + +#ifdef __cplusplus +extern "C" { +#endif + +typedef list_node_t multilist_node_t; +typedef struct multilist multilist_t; +typedef struct multilist_sublist multilist_sublist_t; +typedef unsigned int multilist_sublist_index_func_t(multilist_t *, void *); + +struct multilist_sublist { + /* + * The mutex used internally to implement thread safe insertions + * and removals to this individual sublist. It can also be locked + * by a consumer using multilist_sublist_{lock,unlock}, which is + * useful if a consumer needs to traverse the list in a thread + * safe manner. + */ + kmutex_t mls_lock; + /* + * The actual list object containing all objects in this sublist. + */ + list_t mls_list; + /* + * Pad to cache line, in an effort to try and prevent cache line + * contention. + */ +} ____cacheline_aligned; + +struct multilist { + /* + * This is used to get to the multilist_node_t structure given + * the void *object contained on the list. + */ + size_t ml_offset; + /* + * The number of sublists used internally by this multilist. + */ + uint64_t ml_num_sublists; + /* + * The array of pointers to the actual sublists. + */ + multilist_sublist_t *ml_sublists; + /* + * Pointer to function which determines the sublist to use + * when inserting and removing objects from this multilist. + * Please see the comment above multilist_create for details. + */ + multilist_sublist_index_func_t *ml_index_func; +}; + +void multilist_destroy(multilist_t *); +void multilist_create(multilist_t *, size_t, size_t, unsigned int, + multilist_sublist_index_func_t *); + +void multilist_insert(multilist_t *, void *); +void multilist_remove(multilist_t *, void *); +int multilist_is_empty(multilist_t *); + +unsigned int multilist_get_num_sublists(multilist_t *); +unsigned int multilist_get_random_index(multilist_t *); + +multilist_sublist_t *multilist_sublist_lock(multilist_t *, unsigned int); +void multilist_sublist_unlock(multilist_sublist_t *); + +void multilist_sublist_insert_head(multilist_sublist_t *, void *); +void multilist_sublist_insert_tail(multilist_sublist_t *, void *); +void multilist_sublist_move_forward(multilist_sublist_t *mls, void *obj); +void multilist_sublist_remove(multilist_sublist_t *, void *); + +void *multilist_sublist_head(multilist_sublist_t *); +void *multilist_sublist_tail(multilist_sublist_t *); +void *multilist_sublist_next(multilist_sublist_t *, void *); +void *multilist_sublist_prev(multilist_sublist_t *, void *); + +void multilist_link_init(multilist_node_t *); +int multilist_link_active(multilist_node_t *); + +#ifdef __cplusplus +} +#endif + +#endif /* _SYS_MULTILIST_H */ diff --git a/include/sys/trace_multilist.h b/include/sys/trace_multilist.h new file mode 100644 index 000000000..11d2f2701 --- /dev/null +++ b/include/sys/trace_multilist.h @@ -0,0 +1,76 @@ +/* + * CDDL HEADER START + * + * The contents of this file are subject to the terms of the + * Common Development and Distribution License (the "License"). + * You may not use this file except in compliance with the License. + * + * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE + * or http://www.opensolaris.org/os/licensing. + * See the License for the specific language governing permissions + * and limitations under the License. + * + * When distributing Covered Code, include this CDDL HEADER in each + * file and include the License file at usr/src/OPENSOLARIS.LICENSE. + * If applicable, add the following below this CDDL HEADER, with the + * fields enclosed by brackets "[]" replaced with your own identifying + * information: Portions Copyright [yyyy] [name of copyright owner] + * + * CDDL HEADER END + */ + +#if defined(_KERNEL) && defined(HAVE_DECLARE_EVENT_CLASS) + +#undef TRACE_SYSTEM +#define TRACE_SYSTEM zfs + +#if !defined(_TRACE_MULTILIST_H) || defined(TRACE_HEADER_MULTI_READ) +#define _TRACE_MULTILIST_H + +#include <linux/tracepoint.h> +#include <sys/types.h> + +/* + * Generic support for three argument tracepoints of the form: + * + * DTRACE_PROBE3(..., + * multilist_t *, ..., + * unsigned int, ..., + * void *, ...); + */ + +DECLARE_EVENT_CLASS(zfs_multilist_insert_remove_class, + TP_PROTO(multilist_t *ml, unsigned sublist_idx, void *obj), + TP_ARGS(ml, sublist_idx, obj), + TP_STRUCT__entry( + __field(size_t, ml_offset) + __field(uint64_t, ml_num_sublists) + + __field(unsigned int, sublist_idx) + ), + TP_fast_assign( + __entry->ml_offset = ml->ml_offset; + __entry->ml_num_sublists = ml->ml_num_sublists; + + __entry->sublist_idx = sublist_idx; + ), + TP_printk("ml { offset %ld numsublists %llu sublistidx %u } ", + __entry->ml_offset, __entry->ml_num_sublists, __entry->sublist_idx) +); + +#define DEFINE_MULTILIST_INSERT_REMOVE_EVENT(name) \ +DEFINE_EVENT(zfs_multilist_insert_remove_class, name, \ + TP_PROTO(multilist_t *ml, unsigned int sublist_idx, void *obj), \ + TP_ARGS(ml, sublist_idx, obj)) +DEFINE_MULTILIST_INSERT_REMOVE_EVENT(zfs_multilist__insert); +DEFINE_MULTILIST_INSERT_REMOVE_EVENT(zfs_multilist__remove); + +#endif /* _TRACE_MULTILIST_H */ + +#undef TRACE_INCLUDE_PATH +#undef TRACE_INCLUDE_FILE +#define TRACE_INCLUDE_PATH sys +#define TRACE_INCLUDE_FILE trace_multilist +#include <trace/define_trace.h> + +#endif /* _KERNEL && HAVE_DECLARE_EVENT_CLASS */ diff --git a/include/sys/zfs_context.h b/include/sys/zfs_context.h index 3dc54f1d7..761b1d57a 100644 --- a/include/sys/zfs_context.h +++ b/include/sys/zfs_context.h @@ -609,6 +609,7 @@ extern void delay(clock_t ticks); } while (0); #define max_ncpus 64 +#define num_online_cpus() (sysconf(_SC_NPROCESSORS_ONLN)) #define minclsyspri 60 #define maxclsyspri 99 diff --git a/lib/libzpool/Makefile.am b/lib/libzpool/Makefile.am index 85bc0510a..e25591300 100644 --- a/lib/libzpool/Makefile.am +++ b/lib/libzpool/Makefile.am @@ -55,6 +55,7 @@ libzpool_la_SOURCES = \ $(top_srcdir)/module/zfs/lzjb.c \ $(top_srcdir)/module/zfs/lz4.c \ $(top_srcdir)/module/zfs/metaslab.c \ + $(top_srcdir)/module/zfs/multilist.c \ $(top_srcdir)/module/zfs/range_tree.c \ $(top_srcdir)/module/zfs/refcount.c \ $(top_srcdir)/module/zfs/rrwlock.c \ diff --git a/man/man5/zfs-module-parameters.5 b/man/man5/zfs-module-parameters.5 index 359e9f72f..250adc9ef 100644 --- a/man/man5/zfs-module-parameters.5 +++ b/man/man5/zfs-module-parameters.5 @@ -350,6 +350,19 @@ Default value: \fB8192\fR. .sp .ne 2 .na +\fBzfs_arc_evict_batch_limit\fR (int) +.ad +.RS 12n +Number ARC headers to evict per sub-list before proceding to another sub-list. +This batch-style operation prevents entire sub-lists from being evicted at once +but comes at a cost of additional unlocking and locking. +.sp +Default value: \fB10\fR. +.RE + +.sp +.ne 2 +.na \fBzfs_arc_grow_retry\fR (int) .ad .RS 12n @@ -398,6 +411,19 @@ Default value: \fB0\fR. .sp .ne 2 .na +\fBzfs_arc_meta_min\fR (ulong) +.ad +.RS 12n +The minimum allowed size in bytes that meta data buffers may consume in +the ARC. This value defaults to 0 which disables a floor on the amount +of the ARC devoted meta data. +.sp +Default value: \fB0\fR. +.RE + +.sp +.ne 2 +.na \fBzfs_arc_meta_prune\fR (int) .ad .RS 12n @@ -450,6 +476,40 @@ Default value: \fB100\fR. .sp .ne 2 .na +\fBzfs_arc_num_sublists_per_state\fR (int) +.ad +.RS 12n +To allow more fine-grained locking, each ARC state contains a series +of lists for both data and meta data objects. Locking is performed at +the level of these "sub-lists". This parameters controls the number of +sub-lists per ARC state. +.sp +Default value: 1 or the number of on-online CPUs, whichever is greater +.RE + +.sp +.ne 2 +.na +\fBzfs_arc_overflow_shift\fR (int) +.ad +.RS 12n +The ARC size is considered to be overflowing if it exceeds the current +ARC target size (arc_c) by a threshold determined by this parameter. +The threshold is calculated as a fraction of arc_c using the formula +"arc_c >> \fBzfs_arc_overflow_shift\fR". + +The default value of 8 causes the ARC to be considered to be overflowing +if it exceeds the target size by 1/256th (0.3%) of the target size. + +When the ARC is overflowing, new buffer allocations are stalled until +the reclaim thread catches up and the overflow condition no longer exists. +.sp +Default value: \fB8\fR. +.RE + +.sp +.ne 2 +.na \fBzfs_arc_p_aggressive_disable\fR (int) .ad .RS 12n diff --git a/module/zfs/Makefile.in b/module/zfs/Makefile.in index 954841f33..e5753ae81 100644 --- a/module/zfs/Makefile.in +++ b/module/zfs/Makefile.in @@ -37,6 +37,7 @@ $(MODULE)-objs += @top_srcdir@/module/zfs/gzip.o $(MODULE)-objs += @top_srcdir@/module/zfs/lzjb.o $(MODULE)-objs += @top_srcdir@/module/zfs/lz4.o $(MODULE)-objs += @top_srcdir@/module/zfs/metaslab.o +$(MODULE)-objs += @top_srcdir@/module/zfs/multilist.o $(MODULE)-objs += @top_srcdir@/module/zfs/range_tree.o $(MODULE)-objs += @top_srcdir@/module/zfs/refcount.o $(MODULE)-objs += @top_srcdir@/module/zfs/rrwlock.o diff --git a/module/zfs/arc.c b/module/zfs/arc.c index e69889ab5..67ef87daf 100644 --- a/module/zfs/arc.c +++ b/module/zfs/arc.c @@ -135,6 +135,7 @@ #include <sys/vdev.h> #include <sys/vdev_impl.h> #include <sys/dsl_pool.h> +#include <sys/multilist.h> #ifdef _KERNEL #include <sys/vmsystm.h> #include <vm/anon.h> @@ -154,9 +155,14 @@ boolean_t arc_watch = B_FALSE; #endif -static kmutex_t arc_reclaim_thr_lock; -static kcondvar_t arc_reclaim_thr_cv; /* used to signal reclaim thr */ -static uint8_t arc_thread_exit; +static kmutex_t arc_reclaim_lock; +static kcondvar_t arc_reclaim_thread_cv; +static boolean_t arc_reclaim_thread_exit; +static kcondvar_t arc_reclaim_waiters_cv; + +static kmutex_t arc_user_evicts_lock; +static kcondvar_t arc_user_evicts_cv; +static boolean_t arc_user_evicts_thread_exit; /* number of objects to prune from caches when arc_meta_limit is reached */ int zfs_arc_meta_prune = 10000; @@ -167,14 +173,27 @@ typedef enum arc_reclaim_strategy { } arc_reclaim_strategy_t; /* - * The number of iterations through arc_evict_*() before we - * drop & reacquire the lock. + * The number of headers to evict in arc_evict_state_impl() before + * dropping the sublist lock and evicting from another sublist. A lower + * value means we're more likely to evict the "correct" header (i.e. the + * oldest header in the arc state), but comes with higher overhead + * (i.e. more invocations of arc_evict_state_impl()). */ -int arc_evict_iterations = 100; +int zfs_arc_evict_batch_limit = 10; + +/* + * The number of sublists used for each of the arc state lists. If this + * is not set to a suitable value by the user, it will be configured to + * the number of CPUs on the system in arc_init(). + */ +int zfs_arc_num_sublists_per_state = 0; /* number of seconds before growing cache again */ int zfs_arc_grow_retry = 5; +/* shift of arc_c for calculating overflow limit in arc_get_data_buf */ +int zfs_arc_overflow_shift = 8; + /* disable anon data aggressively growing arc_p */ int zfs_arc_p_aggressive_disable = 1; @@ -200,6 +219,12 @@ int zfs_disable_dup_eviction = 0; int zfs_arc_average_blocksize = 8 * 1024; /* 8KB */ /* + * minimum lifespan of a prefetch block in clock ticks + * (initialized in arc_init()) + */ +static int arc_min_prefetch_lifespan; + +/* * If this percent of memory is free, don't throttle. */ int arc_lotsfree_percent = 10; @@ -220,6 +245,7 @@ static boolean_t arc_warm; unsigned long zfs_arc_max = 0; unsigned long zfs_arc_min = 0; unsigned long zfs_arc_meta_limit = 0; +unsigned long zfs_arc_meta_min = 0; /* * Limit the number of restarts in arc_adjust_meta() @@ -250,7 +276,6 @@ typedef struct arc_stats { kstat_named_t arcstat_mfu_hits; kstat_named_t arcstat_mfu_ghost_hits; kstat_named_t arcstat_deleted; - kstat_named_t arcstat_recycle_miss; /* * Number of buffers that could not be evicted because the hash lock * was held by another thread. The lock may not necessarily be held @@ -264,9 +289,15 @@ typedef struct arc_stats { * not from the spa we're trying to evict from. */ kstat_named_t arcstat_evict_skip; + /* + * Number of times arc_evict_state() was unable to evict enough + * buffers to reach its target amount. + */ + kstat_named_t arcstat_evict_not_enough; kstat_named_t arcstat_evict_l2_cached; kstat_named_t arcstat_evict_l2_eligible; kstat_named_t arcstat_evict_l2_ineligible; + kstat_named_t arcstat_evict_l2_skip; kstat_named_t arcstat_hash_elements; kstat_named_t arcstat_hash_elements_max; kstat_named_t arcstat_hash_collisions; @@ -305,11 +336,12 @@ typedef struct arc_stats { kstat_named_t arcstat_l2_writes_sent; kstat_named_t arcstat_l2_writes_done; kstat_named_t arcstat_l2_writes_error; - kstat_named_t arcstat_l2_writes_hdr_miss; + kstat_named_t arcstat_l2_writes_lock_retry; kstat_named_t arcstat_l2_evict_lock_retry; kstat_named_t arcstat_l2_evict_reading; kstat_named_t arcstat_l2_evict_l1cached; kstat_named_t arcstat_l2_free_on_write; + kstat_named_t arcstat_l2_cdata_free_on_write; kstat_named_t arcstat_l2_abort_lowmem; kstat_named_t arcstat_l2_cksum_bad; kstat_named_t arcstat_l2_io_error; @@ -332,6 +364,7 @@ typedef struct arc_stats { kstat_named_t arcstat_meta_used; kstat_named_t arcstat_meta_limit; kstat_named_t arcstat_meta_max; + kstat_named_t arcstat_meta_min; } arc_stats_t; static arc_stats_t arc_stats = { @@ -350,12 +383,13 @@ static arc_stats_t arc_stats = { { "mfu_hits", KSTAT_DATA_UINT64 }, { "mfu_ghost_hits", KSTAT_DATA_UINT64 }, { "deleted", KSTAT_DATA_UINT64 }, - { "recycle_miss", KSTAT_DATA_UINT64 }, { "mutex_miss", KSTAT_DATA_UINT64 }, { "evict_skip", KSTAT_DATA_UINT64 }, + { "evict_not_enough", KSTAT_DATA_UINT64 }, { "evict_l2_cached", KSTAT_DATA_UINT64 }, { "evict_l2_eligible", KSTAT_DATA_UINT64 }, { "evict_l2_ineligible", KSTAT_DATA_UINT64 }, + { "evict_l2_skip", KSTAT_DATA_UINT64 }, { "hash_elements", KSTAT_DATA_UINT64 }, { "hash_elements_max", KSTAT_DATA_UINT64 }, { "hash_collisions", KSTAT_DATA_UINT64 }, @@ -394,11 +428,12 @@ static arc_stats_t arc_stats = { { "l2_writes_sent", KSTAT_DATA_UINT64 }, { "l2_writes_done", KSTAT_DATA_UINT64 }, { "l2_writes_error", KSTAT_DATA_UINT64 }, - { "l2_writes_hdr_miss", KSTAT_DATA_UINT64 }, + { "l2_writes_lock_retry", KSTAT_DATA_UINT64 }, { "l2_evict_lock_retry", KSTAT_DATA_UINT64 }, { "l2_evict_reading", KSTAT_DATA_UINT64 }, { "l2_evict_l1cached", KSTAT_DATA_UINT64 }, { "l2_free_on_write", KSTAT_DATA_UINT64 }, + { "l2_cdata_free_on_write", KSTAT_DATA_UINT64 }, { "l2_abort_lowmem", KSTAT_DATA_UINT64 }, { "l2_cksum_bad", KSTAT_DATA_UINT64 }, { "l2_io_error", KSTAT_DATA_UINT64 }, @@ -421,6 +456,7 @@ static arc_stats_t arc_stats = { { "arc_meta_used", KSTAT_DATA_UINT64 }, { "arc_meta_limit", KSTAT_DATA_UINT64 }, { "arc_meta_max", KSTAT_DATA_UINT64 }, + { "arc_meta_min", KSTAT_DATA_UINT64 }, }; #define ARCSTAT(stat) (arc_stats.stat.value.ui64) @@ -486,6 +522,7 @@ static arc_state_t *arc_l2c_only; #define arc_tempreserve ARCSTAT(arcstat_tempreserve) #define arc_loaned_bytes ARCSTAT(arcstat_loaned_bytes) #define arc_meta_limit ARCSTAT(arcstat_meta_limit) /* max size for metadata */ +#define arc_meta_min ARCSTAT(arcstat_meta_min) /* min size for metadata */ #define arc_meta_used ARCSTAT(arcstat_meta_used) /* size of metadata */ #define arc_meta_max ARCSTAT(arcstat_meta_max) /* max size of metadata */ @@ -495,7 +532,6 @@ static arc_state_t *arc_l2c_only; static list_t arc_prune_list; static kmutex_t arc_prune_mtx; static arc_buf_t *arc_eviction_list; -static kmutex_t arc_eviction_mtx; static arc_buf_hdr_t arc_eviction_hdr; #define GHOST_STATE(state) \ @@ -637,8 +673,7 @@ static uint8_t l2arc_thread_exit; static void arc_get_data_buf(arc_buf_t *); static void arc_access(arc_buf_hdr_t *, kmutex_t *); -static int arc_evict_needed(arc_buf_contents_t); -static void arc_evict_ghost(arc_state_t *, uint64_t, int64_t); +static boolean_t arc_is_overflowing(void); static void arc_buf_watch(arc_buf_t *); static arc_buf_contents_t arc_buf_type(arc_buf_hdr_t *); @@ -830,6 +865,7 @@ hdr_full_cons(void *vbuf, void *unused, int kmflag) mutex_init(&hdr->b_l1hdr.b_freeze_lock, NULL, MUTEX_DEFAULT, NULL); list_link_init(&hdr->b_l1hdr.b_arc_node); list_link_init(&hdr->b_l2hdr.b_l2node); + multilist_link_init(&hdr->b_l1hdr.b_arc_node); arc_space_consume(HDR_FULL_SIZE, ARC_SPACE_HDRS); return (0); @@ -874,6 +910,7 @@ hdr_full_dest(void *vbuf, void *unused) cv_destroy(&hdr->b_l1hdr.b_cv); refcount_destroy(&hdr->b_l1hdr.b_refcnt); mutex_destroy(&hdr->b_l1hdr.b_freeze_lock); + ASSERT(!multilist_link_active(&hdr->b_l1hdr.b_arc_node)); arc_space_return(HDR_FULL_SIZE, ARC_SPACE_HDRS); } @@ -981,18 +1018,31 @@ arc_hdr_realloc(arc_buf_hdr_t *hdr, kmem_cache_t *old, kmem_cache_t *new) * l2c_only even though it's about to change. */ nhdr->b_l1hdr.b_state = arc_l2c_only; + + /* Verify previous threads set to NULL before freeing */ + ASSERT3P(nhdr->b_l1hdr.b_tmp_cdata, ==, NULL); } else { ASSERT(hdr->b_l1hdr.b_buf == NULL); ASSERT0(hdr->b_l1hdr.b_datacnt); - ASSERT(!list_link_active(&hdr->b_l1hdr.b_arc_node)); + /* - * We might be removing the L1hdr of a buffer which was just - * written out to L2ARC. If such a buffer is compressed then we - * need to free its b_tmp_cdata before destroying the header. + * If we've reached here, We must have been called from + * arc_evict_hdr(), as such we should have already been + * removed from any ghost list we were previously on + * (which protects us from racing with arc_evict_state), + * thus no locking is needed during this check. */ - if (hdr->b_l1hdr.b_tmp_cdata != NULL && - HDR_GET_COMPRESS(hdr) != ZIO_COMPRESS_OFF) - l2arc_release_cdata_buf(hdr); + ASSERT(!multilist_link_active(&hdr->b_l1hdr.b_arc_node)); + + /* + * A buffer must not be moved into the arc_l2c_only + * state if it's not finished being written out to the + * l2arc device. Otherwise, the b_l1hdr.b_tmp_cdata field + * might try to be accessed, even though it was removed. + */ + VERIFY(!HDR_L2_WRITING(hdr)); + VERIFY3P(hdr->b_l1hdr.b_tmp_cdata, ==, NULL); + nhdr->b_flags &= ~ARC_FLAG_HAS_L1HDR; } /* @@ -1188,14 +1238,13 @@ add_reference(arc_buf_hdr_t *hdr, kmutex_t *hash_lock, void *tag) (state != arc_anon)) { /* We don't use the L2-only state list. */ if (state != arc_l2c_only) { + arc_buf_contents_t type = arc_buf_type(hdr); uint64_t delta = hdr->b_size * hdr->b_l1hdr.b_datacnt; - list_t *list = &state->arcs_list[arc_buf_type(hdr)]; - uint64_t *size = &state->arcs_lsize[arc_buf_type(hdr)]; + multilist_t *list = &state->arcs_list[type]; + uint64_t *size = &state->arcs_lsize[type]; + + multilist_remove(list, hdr); - ASSERT(!MUTEX_HELD(&state->arcs_mtx)); - mutex_enter(&state->arcs_mtx); - ASSERT(list_link_active(&hdr->b_l1hdr.b_arc_node)); - list_remove(list, hdr); if (GHOST_STATE(state)) { ASSERT0(hdr->b_l1hdr.b_datacnt); ASSERT3P(hdr->b_l1hdr.b_buf, ==, NULL); @@ -1204,7 +1253,6 @@ add_reference(arc_buf_hdr_t *hdr, kmutex_t *hash_lock, void *tag) ASSERT(delta > 0); ASSERT3U(*size, >=, delta); atomic_add_64(size, -delta); - mutex_exit(&state->arcs_mtx); } /* remove the prefetch flag if we get a reference */ hdr->b_flags &= ~ARC_FLAG_PREFETCH; @@ -1227,16 +1275,15 @@ remove_reference(arc_buf_hdr_t *hdr, kmutex_t *hash_lock, void *tag) */ if (((cnt = refcount_remove(&hdr->b_l1hdr.b_refcnt, tag)) == 0) && (state != arc_anon)) { - uint64_t *size = &state->arcs_lsize[arc_buf_type(hdr)]; + arc_buf_contents_t type = arc_buf_type(hdr); + multilist_t *list = &state->arcs_list[type]; + uint64_t *size = &state->arcs_lsize[type]; + + multilist_insert(list, hdr); - ASSERT(!MUTEX_HELD(&state->arcs_mtx)); - mutex_enter(&state->arcs_mtx); - ASSERT(!list_link_active(&hdr->b_l1hdr.b_arc_node)); - list_insert_head(&state->arcs_list[arc_buf_type(hdr)], hdr); ASSERT(hdr->b_l1hdr.b_datacnt > 0); atomic_add_64(size, hdr->b_size * hdr->b_l1hdr.b_datacnt); - mutex_exit(&state->arcs_mtx); } return (cnt); } @@ -1285,26 +1332,11 @@ arc_buf_info(arc_buf_t *ab, arc_buf_info_t *abi, int state_index) abi->abi_state_type = state ? state->arcs_state : ARC_STATE_ANON; abi->abi_state_contents = arc_buf_type(hdr); - abi->abi_state_index = -1; abi->abi_size = hdr->b_size; - - if (l1hdr && state && state_index && - list_link_active(&l1hdr->b_arc_node)) { - list_t *list = &state->arcs_list[arc_buf_type(hdr)]; - arc_buf_hdr_t *h; - - mutex_enter(&state->arcs_mtx); - for (h = list_head(list); h != NULL; h = list_next(list, h)) { - abi->abi_state_index++; - if (h == hdr) - break; - } - mutex_exit(&state->arcs_mtx); - } } /* - * Move the supplied buffer to the indicated state. The mutex + * Move the supplied buffer to the indicated state. The hash lock * for the buffer must be held by the caller. */ static void @@ -1348,15 +1380,10 @@ arc_change_state(arc_state_t *new_state, arc_buf_hdr_t *hdr, */ if (refcnt == 0) { if (old_state != arc_anon && old_state != arc_l2c_only) { - int use_mutex = !MUTEX_HELD(&old_state->arcs_mtx); uint64_t *size = &old_state->arcs_lsize[buftype]; - if (use_mutex) - mutex_enter(&old_state->arcs_mtx); - ASSERT(HDR_HAS_L1HDR(hdr)); - ASSERT(list_link_active(&hdr->b_l1hdr.b_arc_node)); - list_remove(&old_state->arcs_list[buftype], hdr); + multilist_remove(&old_state->arcs_list[buftype], hdr); /* * If prefetching out of the ghost cache, @@ -1369,12 +1396,8 @@ arc_change_state(arc_state_t *new_state, arc_buf_hdr_t *hdr, } ASSERT3U(*size, >=, from_delta); atomic_add_64(size, -from_delta); - - if (use_mutex) - mutex_exit(&old_state->arcs_mtx); } if (new_state != arc_anon && new_state != arc_l2c_only) { - int use_mutex = !MUTEX_HELD(&new_state->arcs_mtx); uint64_t *size = &new_state->arcs_lsize[buftype]; /* @@ -1384,10 +1407,7 @@ arc_change_state(arc_state_t *new_state, arc_buf_hdr_t *hdr, * beforehand. */ ASSERT(HDR_HAS_L1HDR(hdr)); - if (use_mutex) - mutex_enter(&new_state->arcs_mtx); - - list_insert_head(&new_state->arcs_list[buftype], hdr); + multilist_insert(&new_state->arcs_list[buftype], hdr); /* ghost elements have a ghost size */ if (GHOST_STATE(new_state)) { @@ -1396,9 +1416,6 @@ arc_change_state(arc_state_t *new_state, arc_buf_hdr_t *hdr, to_delta = hdr->b_size; } atomic_add_64(size, to_delta); - - if (use_mutex) - mutex_exit(&new_state->arcs_mtx); } } @@ -1420,8 +1437,8 @@ arc_change_state(arc_state_t *new_state, arc_buf_hdr_t *hdr, * L2 headers should never be on the L2 state list since they don't * have L1 headers allocated. */ - ASSERT(list_is_empty(&arc_l2c_only->arcs_list[ARC_BUFC_DATA]) && - list_is_empty(&arc_l2c_only->arcs_list[ARC_BUFC_METADATA])); + ASSERT(multilist_is_empty(&arc_l2c_only->arcs_list[ARC_BUFC_DATA]) && + multilist_is_empty(&arc_l2c_only->arcs_list[ARC_BUFC_METADATA])); } void @@ -1524,6 +1541,7 @@ arc_buf_alloc(spa_t *spa, uint64_t size, void *tag, arc_buf_contents_t type) hdr->b_l1hdr.b_state = arc_anon; hdr->b_l1hdr.b_arc_access = 0; hdr->b_l1hdr.b_datacnt = 1; + hdr->b_l1hdr.b_tmp_cdata = NULL; arc_get_data_buf(buf); @@ -1654,6 +1672,21 @@ arc_buf_add_ref(arc_buf_t *buf, void* tag) data, metadata, hits); } +static void +arc_buf_free_on_write(void *data, size_t size, + void (*free_func)(void *, size_t)) +{ + l2arc_data_free_t *df; + + df = kmem_alloc(sizeof (*df), KM_SLEEP); + df->l2df_data = data; + df->l2df_size = size; + df->l2df_func = free_func; + mutex_enter(&l2arc_free_on_write_mtx); + list_insert_head(l2arc_free_on_write, df); + mutex_exit(&l2arc_free_on_write_mtx); +} + /* * Free the arc data buffer. If it is an l2arc write in progress, * the buffer is placed on l2arc_free_on_write to be freed later. @@ -1664,26 +1697,74 @@ arc_buf_data_free(arc_buf_t *buf, void (*free_func)(void *, size_t)) arc_buf_hdr_t *hdr = buf->b_hdr; if (HDR_L2_WRITING(hdr)) { - l2arc_data_free_t *df; - df = kmem_alloc(sizeof (l2arc_data_free_t), KM_SLEEP); - df->l2df_data = buf->b_data; - df->l2df_size = hdr->b_size; - df->l2df_func = free_func; - mutex_enter(&l2arc_free_on_write_mtx); - list_insert_head(l2arc_free_on_write, df); - mutex_exit(&l2arc_free_on_write_mtx); + arc_buf_free_on_write(buf->b_data, hdr->b_size, free_func); ARCSTAT_BUMP(arcstat_l2_free_on_write); } else { free_func(buf->b_data, hdr->b_size); } } +static void +arc_buf_l2_cdata_free(arc_buf_hdr_t *hdr) +{ + ASSERT(HDR_HAS_L2HDR(hdr)); + ASSERT(MUTEX_HELD(&hdr->b_l2hdr.b_dev->l2ad_mtx)); + + /* + * The b_tmp_cdata field is linked off of the b_l1hdr, so if + * that doesn't exist, the header is in the arc_l2c_only state, + * and there isn't anything to free (it's already been freed). + */ + if (!HDR_HAS_L1HDR(hdr)) + return; + + /* + * The header isn't being written to the l2arc device, thus it + * shouldn't have a b_tmp_cdata to free. + */ + if (!HDR_L2_WRITING(hdr)) { + ASSERT3P(hdr->b_l1hdr.b_tmp_cdata, ==, NULL); + return; + } + + /* + * The header does not have compression enabled. This can be due + * to the buffer not being compressible, or because we're + * freeing the buffer before the second phase of + * l2arc_write_buffer() has started (which does the compression + * step). In either case, b_tmp_cdata does not point to a + * separately compressed buffer, so there's nothing to free (it + * points to the same buffer as the arc_buf_t's b_data field). + */ + if (HDR_GET_COMPRESS(hdr) == ZIO_COMPRESS_OFF) { + hdr->b_l1hdr.b_tmp_cdata = NULL; + return; + } + + /* + * There's nothing to free since the buffer was all zero's and + * compressed to a zero length buffer. + */ + if (HDR_GET_COMPRESS(hdr) == ZIO_COMPRESS_EMPTY) { + ASSERT3P(hdr->b_l1hdr.b_tmp_cdata, ==, NULL); + return; + } + + ASSERT(L2ARC_IS_VALID_COMPRESS(HDR_GET_COMPRESS(hdr))); + + arc_buf_free_on_write(hdr->b_l1hdr.b_tmp_cdata, + hdr->b_size, zio_data_buf_free); + + ARCSTAT_BUMP(arcstat_l2_cdata_free_on_write); + hdr->b_l1hdr.b_tmp_cdata = NULL; +} + /* * Free up buf->b_data and if 'remove' is set, then pull the * arc_buf_t off of the the arc_buf_hdr_t's list and free it. */ static void -arc_buf_destroy(arc_buf_t *buf, boolean_t recycle, boolean_t remove) +arc_buf_destroy(arc_buf_t *buf, boolean_t remove) { arc_buf_t **bufp; @@ -1696,17 +1777,17 @@ arc_buf_destroy(arc_buf_t *buf, boolean_t recycle, boolean_t remove) arc_cksum_verify(buf); arc_buf_unwatch(buf); - if (!recycle) { - if (type == ARC_BUFC_METADATA) { - arc_buf_data_free(buf, zio_buf_free); - arc_space_return(size, ARC_SPACE_META); - } else { - ASSERT(type == ARC_BUFC_DATA); - arc_buf_data_free(buf, zio_data_buf_free); - arc_space_return(size, ARC_SPACE_DATA); - } + if (type == ARC_BUFC_METADATA) { + arc_buf_data_free(buf, zio_buf_free); + arc_space_return(size, ARC_SPACE_META); + } else { + ASSERT(type == ARC_BUFC_DATA); + arc_buf_data_free(buf, zio_data_buf_free); + arc_space_return(size, ARC_SPACE_DATA); } - if (list_link_active(&buf->b_hdr->b_l1hdr.b_arc_node)) { + + /* protected by hash lock, if in the hash table */ + if (multilist_link_active(&buf->b_hdr->b_l1hdr.b_arc_node)) { uint64_t *cnt = &state->arcs_lsize[type]; ASSERT(refcount_is_zero( @@ -1774,6 +1855,12 @@ arc_hdr_destroy(arc_buf_hdr_t *hdr) list_remove(&l2hdr->b_dev->l2ad_buflist, hdr); + /* + * We don't want to leak the b_tmp_cdata buffer that was + * allocated in l2arc_write_buffers() + */ + arc_buf_l2_cdata_free(hdr); + arc_space_return(HDR_L2ONLY_SIZE, ARC_SPACE_L2HDRS); ARCSTAT_INCR(arcstat_l2_size, -hdr->b_size); ARCSTAT_INCR(arcstat_l2_asize, -l2hdr->b_asize); @@ -1797,27 +1884,26 @@ arc_hdr_destroy(arc_buf_hdr_t *hdr) arc_buf_t *buf = hdr->b_l1hdr.b_buf; if (buf->b_efunc != NULL) { - mutex_enter(&arc_eviction_mtx); + mutex_enter(&arc_user_evicts_lock); mutex_enter(&buf->b_evict_lock); ASSERT(buf->b_hdr != NULL); - arc_buf_destroy(hdr->b_l1hdr.b_buf, FALSE, - FALSE); + arc_buf_destroy(hdr->b_l1hdr.b_buf, FALSE); hdr->b_l1hdr.b_buf = buf->b_next; buf->b_hdr = &arc_eviction_hdr; buf->b_next = arc_eviction_list; arc_eviction_list = buf; mutex_exit(&buf->b_evict_lock); - mutex_exit(&arc_eviction_mtx); + cv_signal(&arc_user_evicts_cv); + mutex_exit(&arc_user_evicts_lock); } else { - arc_buf_destroy(hdr->b_l1hdr.b_buf, FALSE, - TRUE); + arc_buf_destroy(hdr->b_l1hdr.b_buf, TRUE); } } } ASSERT3P(hdr->b_hash_next, ==, NULL); if (HDR_HAS_L1HDR(hdr)) { - ASSERT(!list_link_active(&hdr->b_l1hdr.b_arc_node)); + ASSERT(!multilist_link_active(&hdr->b_l1hdr.b_arc_node)); ASSERT3P(hdr->b_l1hdr.b_acb, ==, NULL); kmem_cache_free(hdr_full_cache, hdr); } else { @@ -1843,7 +1929,7 @@ arc_buf_free(arc_buf_t *buf, void *tag) (void) remove_reference(hdr, hash_lock, tag); if (hdr->b_l1hdr.b_datacnt > 1) { - arc_buf_destroy(buf, FALSE, TRUE); + arc_buf_destroy(buf, TRUE); } else { ASSERT(buf == hdr->b_l1hdr.b_buf); ASSERT(buf->b_efunc == NULL); @@ -1857,16 +1943,16 @@ arc_buf_free(arc_buf_t *buf, void *tag) * this buffer unless the write completes before we finish * decrementing the reference count. */ - mutex_enter(&arc_eviction_mtx); + mutex_enter(&arc_user_evicts_lock); (void) remove_reference(hdr, NULL, tag); ASSERT(refcount_is_zero(&hdr->b_l1hdr.b_refcnt)); destroy_hdr = !HDR_IO_IN_PROGRESS(hdr); - mutex_exit(&arc_eviction_mtx); + mutex_exit(&arc_user_evicts_lock); if (destroy_hdr) arc_hdr_destroy(hdr); } else { if (remove_reference(hdr, NULL, tag) > 0) - arc_buf_destroy(buf, FALSE, TRUE); + arc_buf_destroy(buf, TRUE); else arc_hdr_destroy(hdr); } @@ -1896,7 +1982,7 @@ arc_buf_remove_ref(arc_buf_t *buf, void* tag) (void) remove_reference(hdr, hash_lock, tag); if (hdr->b_l1hdr.b_datacnt > 1) { if (no_callback) - arc_buf_destroy(buf, FALSE, TRUE); + arc_buf_destroy(buf, TRUE); } else if (no_callback) { ASSERT(hdr->b_l1hdr.b_buf == buf && buf->b_next == NULL); ASSERT(buf->b_efunc == NULL); @@ -1957,353 +2043,390 @@ arc_buf_eviction_needed(arc_buf_t *buf) } /* - * Evict buffers from list until we've removed the specified number of - * bytes. Move the removed buffers to the appropriate evict state. - * If the recycle flag is set, then attempt to "recycle" a buffer: - * - look for a buffer to evict that is `bytes' long. - * - return the data block from this buffer rather than freeing it. - * This flag is used by callers that are trying to make space for a - * new buffer in a full arc cache. + * Evict the arc_buf_hdr that is provided as a parameter. The resultant + * state of the header is dependent on its state prior to entering this + * function. The following transitions are possible: * - * This function makes a "best effort". It skips over any buffers - * it can't get a hash_lock on, and so may not catch all candidates. - * It may also return without evicting as much space as requested. + * - arc_mru -> arc_mru_ghost + * - arc_mfu -> arc_mfu_ghost + * - arc_mru_ghost -> arc_l2c_only + * - arc_mru_ghost -> deleted + * - arc_mfu_ghost -> arc_l2c_only + * - arc_mfu_ghost -> deleted */ -static void * -arc_evict(arc_state_t *state, uint64_t spa, int64_t bytes, boolean_t recycle, - arc_buf_contents_t type) +static int64_t +arc_evict_hdr(arc_buf_hdr_t *hdr, kmutex_t *hash_lock) { - arc_state_t *evicted_state; - uint64_t bytes_evicted = 0, skipped = 0, missed = 0; - arc_buf_hdr_t *hdr, *hdr_prev = NULL; - list_t *list = &state->arcs_list[type]; - kmutex_t *hash_lock; - boolean_t have_lock; - void *stolen = NULL; - arc_buf_hdr_t marker = {{{ 0 }}}; - int count = 0; - - ASSERT(state == arc_mru || state == arc_mfu); - - evicted_state = (state == arc_mru) ? arc_mru_ghost : arc_mfu_ghost; + arc_state_t *evicted_state, *state; + int64_t bytes_evicted = 0; -top: - /* - * The ghost list lock must be acquired first in order to prevent - * a 3 party deadlock: - * - * - arc_evict_ghost acquires arc_*_ghost->arcs_mtx, followed by - * l2ad_mtx in arc_hdr_realloc - * - l2arc_write_buffers acquires l2ad_mtx, followed by arc_*->arcs_mtx - * - arc_evict acquires arc_*_ghost->arcs_mtx, followed by - * arc_*_ghost->arcs_mtx and forms a deadlock cycle. - * - * This situation is avoided by acquiring the ghost list lock first. - */ - mutex_enter(&evicted_state->arcs_mtx); - mutex_enter(&state->arcs_mtx); - - for (hdr = list_tail(list); hdr; hdr = hdr_prev) { - hdr_prev = list_prev(list, hdr); - /* prefetch buffers have a minimum lifespan */ - if (HDR_IO_IN_PROGRESS(hdr) || - ((hdr->b_flags & (ARC_FLAG_PREFETCH | ARC_FLAG_INDIRECT)) && - ddi_get_lbolt() - hdr->b_l1hdr.b_arc_access < - zfs_arc_min_prefetch_lifespan)) { - skipped++; - continue; - } - /* "lookahead" for better eviction candidate */ - if (recycle && hdr->b_size != bytes && - hdr_prev && hdr_prev->b_size == bytes) - continue; + ASSERT(MUTEX_HELD(hash_lock)); + ASSERT(HDR_HAS_L1HDR(hdr)); - /* ignore markers */ - if (hdr->b_spa == 0) - continue; + state = hdr->b_l1hdr.b_state; + if (GHOST_STATE(state)) { + ASSERT(!HDR_IO_IN_PROGRESS(hdr)); + ASSERT(hdr->b_l1hdr.b_buf == NULL); /* - * It may take a long time to evict all the bufs requested. - * To avoid blocking all arc activity, periodically drop - * the arcs_mtx and give other threads a chance to run - * before reacquiring the lock. - * - * If we are looking for a buffer to recycle, we are in - * the hot code path, so don't sleep. + * l2arc_write_buffers() relies on a header's L1 portion + * (i.e. its b_tmp_cdata field) during its write phase. + * Thus, we cannot push a header onto the arc_l2c_only + * state (removing its L1 piece) until the header is + * done being written to the l2arc. */ - if (!recycle && count++ > arc_evict_iterations) { - list_insert_after(list, hdr, &marker); - mutex_exit(&state->arcs_mtx); - mutex_exit(&evicted_state->arcs_mtx); - kpreempt(KPREEMPT_SYNC); - mutex_enter(&evicted_state->arcs_mtx); - mutex_enter(&state->arcs_mtx); - hdr_prev = list_prev(list, &marker); - list_remove(list, &marker); - count = 0; - continue; + if (HDR_HAS_L2HDR(hdr) && HDR_L2_WRITING(hdr)) { + ARCSTAT_BUMP(arcstat_evict_l2_skip); + return (bytes_evicted); } - hash_lock = HDR_LOCK(hdr); - have_lock = MUTEX_HELD(hash_lock); - if (have_lock || mutex_tryenter(hash_lock)) { - ASSERT0(refcount_count(&hdr->b_l1hdr.b_refcnt)); - ASSERT3U(hdr->b_l1hdr.b_datacnt, >, 0); - while (hdr->b_l1hdr.b_buf) { - arc_buf_t *buf = hdr->b_l1hdr.b_buf; - if (!mutex_tryenter(&buf->b_evict_lock)) { - missed += 1; - break; - } - if (buf->b_data != NULL) { - bytes_evicted += hdr->b_size; - if (recycle && - arc_buf_type(hdr) == type && - hdr->b_size == bytes && - !HDR_L2_WRITING(hdr)) { - stolen = buf->b_data; - recycle = FALSE; - } - } - if (buf->b_efunc != NULL) { - mutex_enter(&arc_eviction_mtx); - arc_buf_destroy(buf, - buf->b_data == stolen, FALSE); - hdr->b_l1hdr.b_buf = buf->b_next; - buf->b_hdr = &arc_eviction_hdr; - buf->b_next = arc_eviction_list; - arc_eviction_list = buf; - mutex_exit(&arc_eviction_mtx); - mutex_exit(&buf->b_evict_lock); - } else { - mutex_exit(&buf->b_evict_lock); - arc_buf_destroy(buf, - buf->b_data == stolen, TRUE); - } - } + ARCSTAT_BUMP(arcstat_deleted); + bytes_evicted += hdr->b_size; - if (HDR_HAS_L2HDR(hdr)) { - ARCSTAT_INCR(arcstat_evict_l2_cached, - hdr->b_size); - } else { - if (l2arc_write_eligible(hdr->b_spa, hdr)) { - ARCSTAT_INCR(arcstat_evict_l2_eligible, - hdr->b_size); - } else { - ARCSTAT_INCR( - arcstat_evict_l2_ineligible, - hdr->b_size); - } - } + DTRACE_PROBE1(arc__delete, arc_buf_hdr_t *, hdr); - if (hdr->b_l1hdr.b_datacnt == 0) { - arc_change_state(evicted_state, hdr, hash_lock); - ASSERT(HDR_IN_HASH_TABLE(hdr)); - hdr->b_flags |= ARC_FLAG_IN_HASH_TABLE; - hdr->b_flags &= ~ARC_FLAG_BUF_AVAILABLE; - DTRACE_PROBE1(arc__evict, arc_buf_hdr_t *, hdr); - } - if (!have_lock) - mutex_exit(hash_lock); - if (bytes >= 0 && bytes_evicted >= bytes) - break; + if (HDR_HAS_L2HDR(hdr)) { + /* + * This buffer is cached on the 2nd Level ARC; + * don't destroy the header. + */ + arc_change_state(arc_l2c_only, hdr, hash_lock); + /* + * dropping from L1+L2 cached to L2-only, + * realloc to remove the L1 header. + */ + hdr = arc_hdr_realloc(hdr, hdr_full_cache, + hdr_l2only_cache); } else { - missed += 1; + arc_change_state(arc_anon, hdr, hash_lock); + arc_hdr_destroy(hdr); } + return (bytes_evicted); } - mutex_exit(&state->arcs_mtx); - mutex_exit(&evicted_state->arcs_mtx); + ASSERT(state == arc_mru || state == arc_mfu); + evicted_state = (state == arc_mru) ? arc_mru_ghost : arc_mfu_ghost; - if (list == &state->arcs_list[ARC_BUFC_DATA] && - (bytes < 0 || bytes_evicted < bytes)) { - /* Prevent second pass from recycling metadata into data */ - recycle = FALSE; - type = ARC_BUFC_METADATA; - list = &state->arcs_list[type]; - goto top; + /* prefetch buffers have a minimum lifespan */ + if (HDR_IO_IN_PROGRESS(hdr) || + ((hdr->b_flags & (ARC_FLAG_PREFETCH | ARC_FLAG_INDIRECT)) && + ddi_get_lbolt() - hdr->b_l1hdr.b_arc_access < + arc_min_prefetch_lifespan)) { + ARCSTAT_BUMP(arcstat_evict_skip); + return (bytes_evicted); } - if (bytes_evicted < bytes) - dprintf("only evicted %lld bytes from %x\n", - (longlong_t)bytes_evicted, state->arcs_state); + ASSERT0(refcount_count(&hdr->b_l1hdr.b_refcnt)); + ASSERT3U(hdr->b_l1hdr.b_datacnt, >, 0); + while (hdr->b_l1hdr.b_buf) { + arc_buf_t *buf = hdr->b_l1hdr.b_buf; + if (!mutex_tryenter(&buf->b_evict_lock)) { + ARCSTAT_BUMP(arcstat_mutex_miss); + break; + } + if (buf->b_data != NULL) + bytes_evicted += hdr->b_size; + if (buf->b_efunc != NULL) { + mutex_enter(&arc_user_evicts_lock); + arc_buf_destroy(buf, FALSE); + hdr->b_l1hdr.b_buf = buf->b_next; + buf->b_hdr = &arc_eviction_hdr; + buf->b_next = arc_eviction_list; + arc_eviction_list = buf; + cv_signal(&arc_user_evicts_cv); + mutex_exit(&arc_user_evicts_lock); + mutex_exit(&buf->b_evict_lock); + } else { + mutex_exit(&buf->b_evict_lock); + arc_buf_destroy(buf, TRUE); + } + } - if (skipped) - ARCSTAT_INCR(arcstat_evict_skip, skipped); + if (HDR_HAS_L2HDR(hdr)) { + ARCSTAT_INCR(arcstat_evict_l2_cached, hdr->b_size); + } else { + if (l2arc_write_eligible(hdr->b_spa, hdr)) + ARCSTAT_INCR(arcstat_evict_l2_eligible, hdr->b_size); + else + ARCSTAT_INCR(arcstat_evict_l2_ineligible, hdr->b_size); + } - if (missed) - ARCSTAT_INCR(arcstat_mutex_miss, missed); + if (hdr->b_l1hdr.b_datacnt == 0) { + arc_change_state(evicted_state, hdr, hash_lock); + ASSERT(HDR_IN_HASH_TABLE(hdr)); + hdr->b_flags |= ARC_FLAG_IN_HASH_TABLE; + hdr->b_flags &= ~ARC_FLAG_BUF_AVAILABLE; + DTRACE_PROBE1(arc__evict, arc_buf_hdr_t *, hdr); + } - /* - * Note: we have just evicted some data into the ghost state, - * potentially putting the ghost size over the desired size. Rather - * that evicting from the ghost list in this hot code path, leave - * this chore to the arc_reclaim_thread(). - */ - return (stolen); + return (bytes_evicted); } -/* - * Remove buffers from list until we've removed the specified number of - * bytes. Destroy the buffers that are removed. - */ -static void -arc_evict_ghost(arc_state_t *state, uint64_t spa, int64_t bytes) +static uint64_t +arc_evict_state_impl(multilist_t *ml, int idx, arc_buf_hdr_t *marker, + uint64_t spa, int64_t bytes) { - arc_buf_hdr_t *hdr, *hdr_prev; - arc_buf_hdr_t marker; - list_t *list = &state->arcs_list[ARC_BUFC_DATA]; + multilist_sublist_t *mls; + uint64_t bytes_evicted = 0; + arc_buf_hdr_t *hdr; kmutex_t *hash_lock; - uint64_t bytes_deleted = 0; - uint64_t bufs_skipped = 0; - int count = 0; + int evict_count = 0; - ASSERT(GHOST_STATE(state)); - bzero(&marker, sizeof (marker)); -top: - mutex_enter(&state->arcs_mtx); - for (hdr = list_tail(list); hdr; hdr = hdr_prev) { - hdr_prev = list_prev(list, hdr); - if (arc_buf_type(hdr) >= ARC_BUFC_NUMTYPES) - panic("invalid hdr=%p", (void *)hdr); - if (spa && hdr->b_spa != spa) - continue; + ASSERT3P(marker, !=, NULL); + ASSERTV(if (bytes < 0) ASSERT(bytes == ARC_EVICT_ALL)); + + mls = multilist_sublist_lock(ml, idx); + + for (hdr = multilist_sublist_prev(mls, marker); hdr != NULL; + hdr = multilist_sublist_prev(mls, marker)) { + if ((bytes != ARC_EVICT_ALL && bytes_evicted >= bytes) || + (evict_count >= zfs_arc_evict_batch_limit)) + break; - /* ignore markers */ + /* + * To keep our iteration location, move the marker + * forward. Since we're not holding hdr's hash lock, we + * must be very careful and not remove 'hdr' from the + * sublist. Otherwise, other consumers might mistake the + * 'hdr' as not being on a sublist when they call the + * multilist_link_active() function (they all rely on + * the hash lock protecting concurrent insertions and + * removals). multilist_sublist_move_forward() was + * specifically implemented to ensure this is the case + * (only 'marker' will be removed and re-inserted). + */ + multilist_sublist_move_forward(mls, marker); + + /* + * The only case where the b_spa field should ever be + * zero, is the marker headers inserted by + * arc_evict_state(). It's possible for multiple threads + * to be calling arc_evict_state() concurrently (e.g. + * dsl_pool_close() and zio_inject_fault()), so we must + * skip any markers we see from these other threads. + */ if (hdr->b_spa == 0) continue; - hash_lock = HDR_LOCK(hdr); - /* caller may be trying to modify this buffer, skip it */ - if (MUTEX_HELD(hash_lock)) + /* we're only interested in evicting buffers of a certain spa */ + if (spa != 0 && hdr->b_spa != spa) { + ARCSTAT_BUMP(arcstat_evict_skip); continue; + } + + hash_lock = HDR_LOCK(hdr); /* - * It may take a long time to evict all the bufs requested. - * To avoid blocking all arc activity, periodically drop - * the arcs_mtx and give other threads a chance to run - * before reacquiring the lock. + * We aren't calling this function from any code path + * that would already be holding a hash lock, so we're + * asserting on this assumption to be defensive in case + * this ever changes. Without this check, it would be + * possible to incorrectly increment arcstat_mutex_miss + * below (e.g. if the code changed such that we called + * this function with a hash lock held). */ - if (count++ > arc_evict_iterations) { - list_insert_after(list, hdr, &marker); - mutex_exit(&state->arcs_mtx); - kpreempt(KPREEMPT_SYNC); - mutex_enter(&state->arcs_mtx); - hdr_prev = list_prev(list, &marker); - list_remove(list, &marker); - count = 0; - continue; - } + ASSERT(!MUTEX_HELD(hash_lock)); + if (mutex_tryenter(hash_lock)) { - ASSERT(!HDR_IO_IN_PROGRESS(hdr)); - ASSERT(!HDR_HAS_L1HDR(hdr) || - hdr->b_l1hdr.b_buf == NULL); - ARCSTAT_BUMP(arcstat_deleted); - bytes_deleted += hdr->b_size; + uint64_t evicted = arc_evict_hdr(hdr, hash_lock); + mutex_exit(hash_lock); - if (HDR_HAS_L2HDR(hdr)) { - /* - * This buffer is cached on the 2nd Level ARC; - * don't destroy the header. - */ - arc_change_state(arc_l2c_only, hdr, hash_lock); - /* - * dropping from L1+L2 cached to L2-only, - * realloc to remove the L1 header. - */ - hdr = arc_hdr_realloc(hdr, hdr_full_cache, - hdr_l2only_cache); - mutex_exit(hash_lock); - } else { - arc_change_state(arc_anon, hdr, hash_lock); - mutex_exit(hash_lock); - arc_hdr_destroy(hdr); - } + bytes_evicted += evicted; - DTRACE_PROBE1(arc__delete, arc_buf_hdr_t *, hdr); - if (bytes >= 0 && bytes_deleted >= bytes) - break; - } else if (bytes < 0) { /* - * Insert a list marker and then wait for the - * hash lock to become available. Once its - * available, restart from where we left off. + * If evicted is zero, arc_evict_hdr() must have + * decided to skip this header, don't increment + * evict_count in this case. */ - list_insert_after(list, hdr, &marker); - mutex_exit(&state->arcs_mtx); - mutex_enter(hash_lock); - mutex_exit(hash_lock); - mutex_enter(&state->arcs_mtx); - hdr_prev = list_prev(list, &marker); - list_remove(list, &marker); + if (evicted != 0) + evict_count++; + + /* + * If arc_size isn't overflowing, signal any + * threads that might happen to be waiting. + * + * For each header evicted, we wake up a single + * thread. If we used cv_broadcast, we could + * wake up "too many" threads causing arc_size + * to significantly overflow arc_c; since + * arc_get_data_buf() doesn't check for overflow + * when it's woken up (it doesn't because it's + * possible for the ARC to be overflowing while + * full of un-evictable buffers, and the + * function should proceed in this case). + * + * If threads are left sleeping, due to not + * using cv_broadcast, they will be woken up + * just before arc_reclaim_thread() sleeps. + */ + mutex_enter(&arc_reclaim_lock); + if (!arc_is_overflowing()) + cv_signal(&arc_reclaim_waiters_cv); + mutex_exit(&arc_reclaim_lock); } else { - bufs_skipped += 1; + ARCSTAT_BUMP(arcstat_mutex_miss); } } - mutex_exit(&state->arcs_mtx); - if (list == &state->arcs_list[ARC_BUFC_DATA] && - (bytes < 0 || bytes_deleted < bytes)) { - list = &state->arcs_list[ARC_BUFC_METADATA]; - goto top; - } + multilist_sublist_unlock(mls); - if (bufs_skipped) { - ARCSTAT_INCR(arcstat_mutex_miss, bufs_skipped); - ASSERT(bytes >= 0); - } - - if (bytes_deleted < bytes) - dprintf("only deleted %lld bytes from %p\n", - (longlong_t)bytes_deleted, state); + return (bytes_evicted); } -static void -arc_adjust(void) +/* + * Evict buffers from the given arc state, until we've removed the + * specified number of bytes. Move the removed buffers to the + * appropriate evict state. + * + * This function makes a "best effort". It skips over any buffers + * it can't get a hash_lock on, and so, may not catch all candidates. + * It may also return without evicting as much space as requested. + * + * If bytes is specified using the special value ARC_EVICT_ALL, this + * will evict all available (i.e. unlocked and evictable) buffers from + * the given arc state; which is used by arc_flush(). + */ +static uint64_t +arc_evict_state(arc_state_t *state, uint64_t spa, int64_t bytes, + arc_buf_contents_t type) { - int64_t adjustment, delta; + uint64_t total_evicted = 0; + multilist_t *ml = &state->arcs_list[type]; + int num_sublists; + arc_buf_hdr_t **markers; + int i; + + ASSERTV(if (bytes < 0) ASSERT(bytes == ARC_EVICT_ALL)); + + num_sublists = multilist_get_num_sublists(ml); /* - * Adjust MRU size + * If we've tried to evict from each sublist, made some + * progress, but still have not hit the target number of bytes + * to evict, we want to keep trying. The markers allow us to + * pick up where we left off for each individual sublist, rather + * than starting from the tail each time. */ + markers = kmem_zalloc(sizeof (*markers) * num_sublists, KM_SLEEP); + for (i = 0; i < num_sublists; i++) { + multilist_sublist_t *mls; - adjustment = MIN((int64_t)(arc_size - arc_c), - (int64_t)(arc_anon->arcs_size + arc_mru->arcs_size - arc_p)); + markers[i] = kmem_cache_alloc(hdr_full_cache, KM_SLEEP); - if (adjustment > 0 && arc_mru->arcs_size > 0) { - delta = MIN(arc_mru->arcs_size, adjustment); - (void) arc_evict(arc_mru, 0, delta, FALSE, ARC_BUFC_DATA); + /* + * A b_spa of 0 is used to indicate that this header is + * a marker. This fact is used in arc_adjust_type() and + * arc_evict_state_impl(). + */ + markers[i]->b_spa = 0; + + mls = multilist_sublist_lock(ml, i); + multilist_sublist_insert_tail(mls, markers[i]); + multilist_sublist_unlock(mls); } /* - * Adjust MFU size + * While we haven't hit our target number of bytes to evict, or + * we're evicting all available buffers. */ + while (total_evicted < bytes || bytes == ARC_EVICT_ALL) { + /* + * Start eviction using a randomly selected sublist, + * this is to try and evenly balance eviction across all + * sublists. Always starting at the same sublist + * (e.g. index 0) would cause evictions to favor certain + * sublists over others. + */ + int sublist_idx = multilist_get_random_index(ml); + uint64_t scan_evicted = 0; - adjustment = arc_size - arc_c; + for (i = 0; i < num_sublists; i++) { + uint64_t bytes_remaining; + uint64_t bytes_evicted; - if (adjustment > 0 && arc_mfu->arcs_size > 0) { - delta = MIN(arc_mfu->arcs_size, adjustment); - (void) arc_evict(arc_mfu, 0, delta, FALSE, ARC_BUFC_DATA); - } + if (bytes == ARC_EVICT_ALL) + bytes_remaining = ARC_EVICT_ALL; + else if (total_evicted < bytes) + bytes_remaining = bytes - total_evicted; + else + break; - /* - * Adjust ghost lists - */ + bytes_evicted = arc_evict_state_impl(ml, sublist_idx, + markers[sublist_idx], spa, bytes_remaining); + + scan_evicted += bytes_evicted; + total_evicted += bytes_evicted; + + /* we've reached the end, wrap to the beginning */ + if (++sublist_idx >= num_sublists) + sublist_idx = 0; + } - adjustment = arc_mru->arcs_size + arc_mru_ghost->arcs_size - arc_c; + /* + * If we didn't evict anything during this scan, we have + * no reason to believe we'll evict more during another + * scan, so break the loop. + */ + if (scan_evicted == 0) { + /* This isn't possible, let's make that obvious */ + ASSERT3S(bytes, !=, 0); - if (adjustment > 0 && arc_mru_ghost->arcs_size > 0) { - delta = MIN(arc_mru_ghost->arcs_size, adjustment); - arc_evict_ghost(arc_mru_ghost, 0, delta); + /* + * When bytes is ARC_EVICT_ALL, the only way to + * break the loop is when scan_evicted is zero. + * In that case, we actually have evicted enough, + * so we don't want to increment the kstat. + */ + if (bytes != ARC_EVICT_ALL) { + ASSERT3S(total_evicted, <, bytes); + ARCSTAT_BUMP(arcstat_evict_not_enough); + } + + break; + } } - adjustment = - arc_mru_ghost->arcs_size + arc_mfu_ghost->arcs_size - arc_c; + for (i = 0; i < num_sublists; i++) { + multilist_sublist_t *mls = multilist_sublist_lock(ml, i); + multilist_sublist_remove(mls, markers[i]); + multilist_sublist_unlock(mls); - if (adjustment > 0 && arc_mfu_ghost->arcs_size > 0) { - delta = MIN(arc_mfu_ghost->arcs_size, adjustment); - arc_evict_ghost(arc_mfu_ghost, 0, delta); + kmem_cache_free(hdr_full_cache, markers[i]); } + kmem_free(markers, sizeof (*markers) * num_sublists); + + return (total_evicted); +} + +/* + * Flush all "evictable" data of the given type from the arc state + * specified. This will not evict any "active" buffers (i.e. referenced). + * + * When 'retry' is set to FALSE, the function will make a single pass + * over the state and evict any buffers that it can. Since it doesn't + * continually retry the eviction, it might end up leaving some buffers + * in the ARC due to lock misses. + * + * When 'retry' is set to TRUE, the function will continually retry the + * eviction until *all* evictable buffers have been removed from the + * state. As a result, if concurrent insertions into the state are + * allowed (e.g. if the ARC isn't shutting down), this function might + * wind up in an infinite loop, continually trying to evict buffers. + */ +static uint64_t +arc_flush_state(arc_state_t *state, uint64_t spa, arc_buf_contents_t type, + boolean_t retry) +{ + uint64_t evicted = 0; + + while (state->arcs_lsize[type] != 0) { + evicted += arc_evict_state(state, spa, ARC_EVICT_ALL, type); + + if (!retry) + break; + } + + return (evicted); } /* @@ -2348,27 +2471,26 @@ arc_do_user_prune(int64_t adjustment) mutex_exit(&arc_prune_mtx); } -static void -arc_do_user_evicts(void) +/* + * Evict the specified number of bytes from the state specified, + * restricting eviction to the spa and type given. This function + * prevents us from trying to evict more from a state's list than + * is "evictable", and to skip evicting altogether when passed a + * negative value for "bytes". In contrast, arc_evict_state() will + * evict everything it can, when passed a negative value for "bytes". + */ +static uint64_t +arc_adjust_impl(arc_state_t *state, uint64_t spa, int64_t bytes, + arc_buf_contents_t type) { - mutex_enter(&arc_eviction_mtx); - while (arc_eviction_list != NULL) { - arc_buf_t *buf = arc_eviction_list; - arc_eviction_list = buf->b_next; - mutex_enter(&buf->b_evict_lock); - buf->b_hdr = NULL; - mutex_exit(&buf->b_evict_lock); - mutex_exit(&arc_eviction_mtx); - - if (buf->b_efunc != NULL) - VERIFY0(buf->b_efunc(buf->b_private)); + int64_t delta; - buf->b_efunc = NULL; - buf->b_private = NULL; - kmem_cache_free(buf_cache, buf); - mutex_enter(&arc_eviction_mtx); + if (bytes > 0 && state->arcs_lsize[type] > 0) { + delta = MIN(state->arcs_lsize[type], bytes); + return (arc_evict_state(state, spa, delta, type)); } - mutex_exit(&arc_eviction_mtx); + + return (0); } /* @@ -2388,10 +2510,11 @@ arc_do_user_evicts(void) * be dropped from the VFS cache. This will make dnode meta data buffers * available for reclaim. */ -static void +static uint64_t arc_adjust_meta(void) { int64_t adjustmnt, delta, prune = 0; + uint64_t total_evicted = 0; arc_buf_contents_t type = ARC_BUFC_DATA; unsigned long restarts = zfs_arc_meta_adjust_restarts; @@ -2408,7 +2531,7 @@ restart: if (adjustmnt > 0 && arc_mru->arcs_lsize[type] > 0) { delta = MIN(arc_mru->arcs_lsize[type], adjustmnt); - arc_evict(arc_mru, 0, delta, FALSE, type); + total_evicted += arc_adjust_impl(arc_mru, 0, delta, type); adjustmnt -= delta; } @@ -2424,21 +2547,22 @@ restart: if (adjustmnt > 0 && arc_mfu->arcs_lsize[type] > 0) { delta = MIN(arc_mfu->arcs_lsize[type], adjustmnt); - arc_evict(arc_mfu, 0, delta, FALSE, type); + total_evicted += arc_adjust_impl(arc_mfu, 0, delta, type); } adjustmnt = arc_meta_used - arc_meta_limit; if (adjustmnt > 0 && arc_mru_ghost->arcs_lsize[type] > 0) { delta = MIN(adjustmnt, - arc_mru_ghost->arcs_lsize[ARC_BUFC_METADATA]); - arc_evict_ghost(arc_mru_ghost, 0, delta); + arc_mru_ghost->arcs_lsize[type]); + total_evicted += arc_adjust_impl(arc_mru_ghost, 0, delta, type); + adjustmnt -= delta; } if (adjustmnt > 0 && arc_mfu_ghost->arcs_lsize[type] > 0) { delta = MIN(adjustmnt, - arc_mfu_ghost->arcs_lsize[ARC_BUFC_METADATA]); - arc_evict_ghost(arc_mfu_ghost, 0, delta); + arc_mfu_ghost->arcs_lsize[type]); + total_evicted += arc_adjust_impl(arc_mfu_ghost, 0, delta, type); } /* @@ -2465,47 +2589,278 @@ restart: goto restart; } } + return (total_evicted); } /* - * Flush all *evictable* data from the cache for the given spa. - * NOTE: this will not touch "active" (i.e. referenced) data. + * Return the type of the oldest buffer in the given arc state + * + * This function will select a random sublist of type ARC_BUFC_DATA and + * a random sublist of type ARC_BUFC_METADATA. The tail of each sublist + * is compared, and the type which contains the "older" buffer will be + * returned. */ -void -arc_flush(spa_t *spa) +static arc_buf_contents_t +arc_adjust_type(arc_state_t *state) { - uint64_t guid = 0; + multilist_t *data_ml = &state->arcs_list[ARC_BUFC_DATA]; + multilist_t *meta_ml = &state->arcs_list[ARC_BUFC_METADATA]; + int data_idx = multilist_get_random_index(data_ml); + int meta_idx = multilist_get_random_index(meta_ml); + multilist_sublist_t *data_mls; + multilist_sublist_t *meta_mls; + arc_buf_contents_t type; + arc_buf_hdr_t *data_hdr; + arc_buf_hdr_t *meta_hdr; - if (spa != NULL) - guid = spa_load_guid(spa); + /* + * We keep the sublist lock until we're finished, to prevent + * the headers from being destroyed via arc_evict_state(). + */ + data_mls = multilist_sublist_lock(data_ml, data_idx); + meta_mls = multilist_sublist_lock(meta_ml, meta_idx); + + /* + * These two loops are to ensure we skip any markers that + * might be at the tail of the lists due to arc_evict_state(). + */ - while (list_head(&arc_mru->arcs_list[ARC_BUFC_DATA])) { - (void) arc_evict(arc_mru, guid, -1, FALSE, ARC_BUFC_DATA); - if (spa != NULL) + for (data_hdr = multilist_sublist_tail(data_mls); data_hdr != NULL; + data_hdr = multilist_sublist_prev(data_mls, data_hdr)) { + if (data_hdr->b_spa != 0) break; } - while (list_head(&arc_mru->arcs_list[ARC_BUFC_METADATA])) { - (void) arc_evict(arc_mru, guid, -1, FALSE, ARC_BUFC_METADATA); - if (spa != NULL) + + for (meta_hdr = multilist_sublist_tail(meta_mls); meta_hdr != NULL; + meta_hdr = multilist_sublist_prev(meta_mls, meta_hdr)) { + if (meta_hdr->b_spa != 0) break; } - while (list_head(&arc_mfu->arcs_list[ARC_BUFC_DATA])) { - (void) arc_evict(arc_mfu, guid, -1, FALSE, ARC_BUFC_DATA); - if (spa != NULL) - break; + + if (data_hdr == NULL && meta_hdr == NULL) { + type = ARC_BUFC_DATA; + } else if (data_hdr == NULL) { + ASSERT3P(meta_hdr, !=, NULL); + type = ARC_BUFC_METADATA; + } else if (meta_hdr == NULL) { + ASSERT3P(data_hdr, !=, NULL); + type = ARC_BUFC_DATA; + } else { + ASSERT3P(data_hdr, !=, NULL); + ASSERT3P(meta_hdr, !=, NULL); + + /* The headers can't be on the sublist without an L1 header */ + ASSERT(HDR_HAS_L1HDR(data_hdr)); + ASSERT(HDR_HAS_L1HDR(meta_hdr)); + + if (data_hdr->b_l1hdr.b_arc_access < + meta_hdr->b_l1hdr.b_arc_access) { + type = ARC_BUFC_DATA; + } else { + type = ARC_BUFC_METADATA; + } } - while (list_head(&arc_mfu->arcs_list[ARC_BUFC_METADATA])) { - (void) arc_evict(arc_mfu, guid, -1, FALSE, ARC_BUFC_METADATA); - if (spa != NULL) - break; + + multilist_sublist_unlock(meta_mls); + multilist_sublist_unlock(data_mls); + + return (type); +} + +/* + * Evict buffers from the cache, such that arc_size is capped by arc_c. + */ +static uint64_t +arc_adjust(void) +{ + uint64_t total_evicted = 0; + uint64_t bytes; + int64_t target; + + /* + * If we're over arc_meta_limit, we want to correct that before + * potentially evicting data buffers below. + */ + total_evicted += arc_adjust_meta(); + + /* + * Adjust MRU size + * + * If we're over the target cache size, we want to evict enough + * from the list to get back to our target size. We don't want + * to evict too much from the MRU, such that it drops below + * arc_p. So, if we're over our target cache size more than + * the MRU is over arc_p, we'll evict enough to get back to + * arc_p here, and then evict more from the MFU below. + */ + target = MIN((int64_t)(arc_size - arc_c), + (int64_t)(arc_anon->arcs_size + arc_mru->arcs_size + arc_meta_used - + arc_p)); + + /* + * If we're below arc_meta_min, always prefer to evict data. + * Otherwise, try to satisfy the requested number of bytes to + * evict from the type which contains older buffers; in an + * effort to keep newer buffers in the cache regardless of their + * type. If we cannot satisfy the number of bytes from this + * type, spill over into the next type. + */ + if (arc_adjust_type(arc_mru) == ARC_BUFC_METADATA && + arc_meta_used > arc_meta_min) { + bytes = arc_adjust_impl(arc_mru, 0, target, ARC_BUFC_METADATA); + total_evicted += bytes; + + /* + * If we couldn't evict our target number of bytes from + * metadata, we try to get the rest from data. + */ + target -= bytes; + + total_evicted += + arc_adjust_impl(arc_mru, 0, target, ARC_BUFC_DATA); + } else { + bytes = arc_adjust_impl(arc_mru, 0, target, ARC_BUFC_DATA); + total_evicted += bytes; + + /* + * If we couldn't evict our target number of bytes from + * data, we try to get the rest from metadata. + */ + target -= bytes; + + total_evicted += + arc_adjust_impl(arc_mru, 0, target, ARC_BUFC_METADATA); + } + + /* + * Adjust MFU size + * + * Now that we've tried to evict enough from the MRU to get its + * size back to arc_p, if we're still above the target cache + * size, we evict the rest from the MFU. + */ + target = arc_size - arc_c; + + if (arc_adjust_type(arc_mru) == ARC_BUFC_METADATA && + arc_meta_used > arc_meta_min) { + bytes = arc_adjust_impl(arc_mfu, 0, target, ARC_BUFC_METADATA); + total_evicted += bytes; + + /* + * If we couldn't evict our target number of bytes from + * metadata, we try to get the rest from data. + */ + target -= bytes; + + total_evicted += + arc_adjust_impl(arc_mfu, 0, target, ARC_BUFC_DATA); + } else { + bytes = arc_adjust_impl(arc_mfu, 0, target, ARC_BUFC_DATA); + total_evicted += bytes; + + /* + * If we couldn't evict our target number of bytes from + * data, we try to get the rest from data. + */ + target -= bytes; + + total_evicted += + arc_adjust_impl(arc_mfu, 0, target, ARC_BUFC_METADATA); + } + + /* + * Adjust ghost lists + * + * In addition to the above, the ARC also defines target values + * for the ghost lists. The sum of the mru list and mru ghost + * list should never exceed the target size of the cache, and + * the sum of the mru list, mfu list, mru ghost list, and mfu + * ghost list should never exceed twice the target size of the + * cache. The following logic enforces these limits on the ghost + * caches, and evicts from them as needed. + */ + target = arc_mru->arcs_size + arc_mru_ghost->arcs_size - arc_c; + + bytes = arc_adjust_impl(arc_mru_ghost, 0, target, ARC_BUFC_DATA); + total_evicted += bytes; + + target -= bytes; + + total_evicted += + arc_adjust_impl(arc_mru_ghost, 0, target, ARC_BUFC_METADATA); + + /* + * We assume the sum of the mru list and mfu list is less than + * or equal to arc_c (we enforced this above), which means we + * can use the simpler of the two equations below: + * + * mru + mfu + mru ghost + mfu ghost <= 2 * arc_c + * mru ghost + mfu ghost <= arc_c + */ + target = arc_mru_ghost->arcs_size + arc_mfu_ghost->arcs_size - arc_c; + + bytes = arc_adjust_impl(arc_mfu_ghost, 0, target, ARC_BUFC_DATA); + total_evicted += bytes; + + target -= bytes; + + total_evicted += + arc_adjust_impl(arc_mfu_ghost, 0, target, ARC_BUFC_METADATA); + + return (total_evicted); +} + +static void +arc_do_user_evicts(void) +{ + mutex_enter(&arc_user_evicts_lock); + while (arc_eviction_list != NULL) { + arc_buf_t *buf = arc_eviction_list; + arc_eviction_list = buf->b_next; + mutex_enter(&buf->b_evict_lock); + buf->b_hdr = NULL; + mutex_exit(&buf->b_evict_lock); + mutex_exit(&arc_user_evicts_lock); + + if (buf->b_efunc != NULL) + VERIFY0(buf->b_efunc(buf->b_private)); + + buf->b_efunc = NULL; + buf->b_private = NULL; + kmem_cache_free(buf_cache, buf); + mutex_enter(&arc_user_evicts_lock); } + mutex_exit(&arc_user_evicts_lock); +} + +void +arc_flush(spa_t *spa, boolean_t retry) +{ + uint64_t guid = 0; + + /* + * If retry is TRUE, a spa must not be specified since we have + * no good way to determine if all of a spa's buffers have been + * evicted from an arc state. + */ + ASSERT(!retry || spa == 0); + + if (spa != NULL) + guid = spa_load_guid(spa); - arc_evict_ghost(arc_mru_ghost, guid, -1); - arc_evict_ghost(arc_mfu_ghost, guid, -1); + (void) arc_flush_state(arc_mru, guid, ARC_BUFC_DATA, retry); + (void) arc_flush_state(arc_mru, guid, ARC_BUFC_METADATA, retry); + + (void) arc_flush_state(arc_mfu, guid, ARC_BUFC_DATA, retry); + (void) arc_flush_state(arc_mfu, guid, ARC_BUFC_METADATA, retry); + + (void) arc_flush_state(arc_mru_ghost, guid, ARC_BUFC_DATA, retry); + (void) arc_flush_state(arc_mru_ghost, guid, ARC_BUFC_METADATA, retry); + + (void) arc_flush_state(arc_mfu_ghost, guid, ARC_BUFC_DATA, retry); + (void) arc_flush_state(arc_mfu_ghost, guid, ARC_BUFC_METADATA, retry); - mutex_enter(&arc_reclaim_thr_lock); arc_do_user_evicts(); - mutex_exit(&arc_reclaim_thr_lock); ASSERT(spa || arc_eviction_list == NULL); } @@ -2538,7 +2893,7 @@ arc_shrink(uint64_t bytes) } if (arc_size > arc_c) - arc_adjust(); + (void) arc_adjust(); } static void @@ -2568,6 +2923,7 @@ arc_kmem_reap_now(arc_reclaim_strategy_t strat, uint64_t bytes) } } + kmem_cache_reap_now(buf_cache); kmem_cache_reap_now(hdr_full_cache); kmem_cache_reap_now(hdr_l2only_cache); } @@ -2578,21 +2934,41 @@ arc_kmem_reap_now(arc_reclaim_strategy_t strat, uint64_t bytes) * reclamation has been entirely delegated to the arc_shrinker_func() * which is registered with the VM. To reflect this change in behavior * the arc_reclaim thread has been renamed to arc_adapt. + * + * The following comment from arc_reclaim_thread() in illumos is still + * applicable: + * + * Threads can block in arc_get_data_buf() waiting for this thread to evict + * enough data and signal them to proceed. When this happens, the threads in + * arc_get_data_buf() are sleeping while holding the hash lock for their + * particular arc header. Thus, we must be careful to never sleep on a + * hash lock in this thread. This is to prevent the following deadlock: + * + * - Thread A sleeps on CV in arc_get_data_buf() holding hash lock "L", + * waiting for the reclaim thread to signal it. + * + * - arc_reclaim_thread() tries to acquire hash lock "L" using mutex_enter, + * fails, and goes to sleep forever. + * + * This possible deadlock is avoided by always acquiring a hash lock + * using mutex_tryenter() from arc_reclaim_thread(). */ static void arc_adapt_thread(void) { callb_cpr_t cpr; fstrans_cookie_t cookie; + uint64_t arc_evicted; - CALLB_CPR_INIT(&cpr, &arc_reclaim_thr_lock, callb_generic_cpr, FTAG); + CALLB_CPR_INIT(&cpr, &arc_reclaim_lock, callb_generic_cpr, FTAG); cookie = spl_fstrans_mark(); - mutex_enter(&arc_reclaim_thr_lock); - while (arc_thread_exit == 0) { + mutex_enter(&arc_reclaim_lock); + while (arc_reclaim_thread_exit == 0) { #ifndef _KERNEL arc_reclaim_strategy_t last_reclaim = ARC_RECLAIM_CONS; + mutex_exit(&arc_reclaim_lock); if (spa_get_random(100) == 0) { if (arc_no_grow) { @@ -2614,6 +2990,8 @@ arc_adapt_thread(void) arc_kmem_reap_now(last_reclaim, 0); arc_warm = B_TRUE; } +#else /* _KERNEL */ + mutex_exit(&arc_reclaim_lock); #endif /* !_KERNEL */ /* No recent memory pressure allow the ARC to grow. */ @@ -2621,18 +2999,23 @@ arc_adapt_thread(void) ddi_time_after_eq(ddi_get_lbolt(), arc_grow_time)) arc_no_grow = FALSE; - arc_adjust_meta(); + arc_evicted = arc_adjust(); - arc_adjust(); + /* + * We're either no longer overflowing, or we + * can't evict anything more, so we should wake + * up any threads before we go to sleep. + */ + if (arc_size <= arc_c || arc_evicted == 0) + cv_broadcast(&arc_reclaim_waiters_cv); - if (arc_eviction_list != NULL) - arc_do_user_evicts(); + mutex_enter(&arc_reclaim_lock); /* block until needed, or one second, whichever is shorter */ CALLB_CPR_SAFE_BEGIN(&cpr); - (void) cv_timedwait_interruptible(&arc_reclaim_thr_cv, - &arc_reclaim_thr_lock, (ddi_get_lbolt() + hz)); - CALLB_CPR_SAFE_END(&cpr, &arc_reclaim_thr_lock); + (void) cv_timedwait_interruptible(&arc_reclaim_thread_cv, + &arc_reclaim_lock, (ddi_get_lbolt() + hz)); + CALLB_CPR_SAFE_END(&cpr, &arc_reclaim_lock); /* Allow the module options to be changed */ @@ -2650,14 +3033,59 @@ arc_adapt_thread(void) zfs_arc_meta_limit <= arc_c_max && zfs_arc_meta_limit != arc_meta_limit) arc_meta_limit = zfs_arc_meta_limit; + } + + arc_reclaim_thread_exit = 0; + cv_broadcast(&arc_reclaim_thread_cv); + CALLB_CPR_EXIT(&cpr); /* drops arc_reclaim_lock */ + spl_fstrans_unmark(cookie); + thread_exit(); +} + +static void +arc_user_evicts_thread(void) +{ + callb_cpr_t cpr; + fstrans_cookie_t cookie; + CALLB_CPR_INIT(&cpr, &arc_user_evicts_lock, callb_generic_cpr, FTAG); + cookie = spl_fstrans_mark(); + mutex_enter(&arc_user_evicts_lock); + while (!arc_user_evicts_thread_exit) { + mutex_exit(&arc_user_evicts_lock); + + arc_do_user_evicts(); + /* + * This is necessary in order for the mdb ::arc dcmd to + * show up to date information. Since the ::arc command + * does not call the kstat's update function, without + * this call, the command may show stale stats for the + * anon, mru, mru_ghost, mfu, and mfu_ghost lists. Even + * with this change, the data might be up to 1 second + * out of date; but that should suffice. The arc_state_t + * structures can be queried directly if more accurate + * information is needed. + */ + if (arc_ksp != NULL) + arc_ksp->ks_update(arc_ksp, KSTAT_READ); + + mutex_enter(&arc_user_evicts_lock); + + /* + * Block until signaled, or after one second (we need to + * call the arc's kstat update function regularly). + */ + CALLB_CPR_SAFE_BEGIN(&cpr); + (void) cv_timedwait_interruptible(&arc_user_evicts_cv, + &arc_user_evicts_lock, ddi_get_lbolt() + hz); + CALLB_CPR_SAFE_END(&cpr, &arc_user_evicts_lock); } - arc_thread_exit = 0; - cv_broadcast(&arc_reclaim_thr_cv); - CALLB_CPR_EXIT(&cpr); /* drops arc_reclaim_thr_lock */ + arc_user_evicts_thread_exit = FALSE; + cv_broadcast(&arc_user_evicts_cv); + CALLB_CPR_EXIT(&cpr); /* drops arc_user_evicts_lock */ spl_fstrans_unmark(cookie); thread_exit(); } @@ -2759,9 +3187,11 @@ __arc_shrinker_func(struct shrinker *shrink, struct shrink_control *sc) return (SHRINK_STOP); /* Reclaim in progress */ - if (mutex_tryenter(&arc_reclaim_thr_lock) == 0) + if (mutex_tryenter(&arc_reclaim_lock) == 0) return (SHRINK_STOP); + mutex_exit(&arc_reclaim_lock); + /* * Evict the requested number of pages by shrinking arc_c the * requested amount. If there is nothing left to evict just @@ -2781,6 +3211,11 @@ __arc_shrinker_func(struct shrinker *shrink, struct shrink_control *sc) } /* + * We've reaped what we can, wake up threads. + */ + cv_broadcast(&arc_reclaim_waiters_cv); + + /* * When direct reclaim is observed it usually indicates a rapid * increase in memory pressure. This occurs because the kswapd * threads were unable to asynchronously keep enough free memory @@ -2795,8 +3230,6 @@ __arc_shrinker_func(struct shrinker *shrink, struct shrink_control *sc) ARCSTAT_BUMP(arcstat_memory_direct_count); } - mutex_exit(&arc_reclaim_thr_lock); - return (pages); } SPL_SHRINKER_CALLBACK_WRAPPER(arc_shrinker_func); @@ -2871,43 +3304,25 @@ arc_adapt(int bytes, arc_state_t *state) } /* - * Check if the cache has reached its limits and eviction is required - * prior to insert. + * Check if arc_size has grown past our upper threshold, determined by + * zfs_arc_overflow_shift. */ -static int -arc_evict_needed(arc_buf_contents_t type) +static boolean_t +arc_is_overflowing(void) { - if (type == ARC_BUFC_METADATA && arc_meta_used >= arc_meta_limit) - return (1); - - if (arc_no_grow) - return (1); + /* Always allow at least one block of overflow */ + uint64_t overflow = MAX(SPA_MAXBLOCKSIZE, + arc_c >> zfs_arc_overflow_shift); - return (arc_size > arc_c); + return (arc_size >= arc_c + overflow); } /* - * The buffer, supplied as the first argument, needs a data block. - * So, if we are at cache max, determine which cache should be victimized. - * We have the following cases: - * - * 1. Insert for MRU, p > sizeof(arc_anon + arc_mru) -> - * In this situation if we're out of space, but the resident size of the MFU is - * under the limit, victimize the MFU cache to satisfy this insertion request. - * - * 2. Insert for MRU, p <= sizeof(arc_anon + arc_mru) -> - * Here, we've used up all of the available space for the MRU, so we need to - * evict from our own cache instead. Evict from the set of resident MRU - * entries. - * - * 3. Insert for MFU (c - p) > sizeof(arc_mfu) -> - * c minus p represents the MFU space in the cache, since p is the size of the - * cache that is dedicated to the MRU. In this situation there's still space on - * the MFU side, so the MRU side needs to be victimized. - * - * 4. Insert for MFU (c - p) < sizeof(arc_mfu) -> - * MFU's resident set is consuming more space than it has been allotted. In - * this situation, we must victimize our own cache, the MFU, for this insertion. + * The buffer, supplied as the first argument, needs a data block. If we + * are hitting the hard limit for the cache size, we must sleep, waiting + * for the eviction thread to catch up. If we're past the target size + * but below the hard limit, we'll only signal the reclaim thread and + * continue on. */ static void arc_get_data_buf(arc_buf_t *buf) @@ -2915,91 +3330,54 @@ arc_get_data_buf(arc_buf_t *buf) arc_state_t *state = buf->b_hdr->b_l1hdr.b_state; uint64_t size = buf->b_hdr->b_size; arc_buf_contents_t type = arc_buf_type(buf->b_hdr); - arc_buf_contents_t evict = ARC_BUFC_DATA; - boolean_t recycle = TRUE; arc_adapt(size, state); /* - * We have not yet reached cache maximum size, - * just allocate a new buffer. + * If arc_size is currently overflowing, and has grown past our + * upper limit, we must be adding data faster than the evict + * thread can evict. Thus, to ensure we don't compound the + * problem by adding more data and forcing arc_size to grow even + * further past it's target size, we halt and wait for the + * eviction thread to catch up. + * + * It's also possible that the reclaim thread is unable to evict + * enough buffers to get arc_size below the overflow limit (e.g. + * due to buffers being un-evictable, or hash lock collisions). + * In this case, we want to proceed regardless if we're + * overflowing; thus we don't use a while loop here. */ - if (!arc_evict_needed(type)) { - if (type == ARC_BUFC_METADATA) { - buf->b_data = zio_buf_alloc(size); - arc_space_consume(size, ARC_SPACE_META); - } else { - ASSERT(type == ARC_BUFC_DATA); - buf->b_data = zio_data_buf_alloc(size); - arc_space_consume(size, ARC_SPACE_DATA); + if (arc_is_overflowing()) { + mutex_enter(&arc_reclaim_lock); + + /* + * Now that we've acquired the lock, we may no longer be + * over the overflow limit, lets check. + * + * We're ignoring the case of spurious wake ups. If that + * were to happen, it'd let this thread consume an ARC + * buffer before it should have (i.e. before we're under + * the overflow limit and were signalled by the reclaim + * thread). As long as that is a rare occurrence, it + * shouldn't cause any harm. + */ + if (arc_is_overflowing()) { + cv_signal(&arc_reclaim_thread_cv); + cv_wait(&arc_reclaim_waiters_cv, &arc_reclaim_lock); } - goto out; - } - /* - * If we are prefetching from the mfu ghost list, this buffer - * will end up on the mru list; so steal space from there. - */ - if (state == arc_mfu_ghost) - state = HDR_PREFETCH(buf->b_hdr) ? arc_mru : arc_mfu; - else if (state == arc_mru_ghost) - state = arc_mru; - - if (state == arc_mru || state == arc_anon) { - uint64_t mru_used = arc_anon->arcs_size + arc_mru->arcs_size; - state = (arc_mfu->arcs_lsize[type] >= size && - arc_p > mru_used) ? arc_mfu : arc_mru; - } else { - /* MFU cases */ - uint64_t mfu_space = arc_c - arc_p; - state = (arc_mru->arcs_lsize[type] >= size && - mfu_space > arc_mfu->arcs_size) ? arc_mru : arc_mfu; + mutex_exit(&arc_reclaim_lock); } - /* - * Evict data buffers prior to metadata buffers, unless we're - * over the metadata limit and adding a metadata buffer. - */ if (type == ARC_BUFC_METADATA) { - if (arc_meta_used >= arc_meta_limit) - evict = ARC_BUFC_METADATA; - else - /* - * In this case, we're evicting data while - * adding metadata. Thus, to prevent recycling a - * data buffer into a metadata buffer, recycling - * is disabled in the following arc_evict call. - */ - recycle = FALSE; + buf->b_data = zio_buf_alloc(size); + arc_space_consume(size, ARC_SPACE_META); + } else { + ASSERT(type == ARC_BUFC_DATA); + buf->b_data = zio_data_buf_alloc(size); + arc_space_consume(size, ARC_SPACE_DATA); } - if ((buf->b_data = arc_evict(state, 0, size, recycle, evict)) == NULL) { - if (type == ARC_BUFC_METADATA) { - buf->b_data = zio_buf_alloc(size); - arc_space_consume(size, ARC_SPACE_META); - - /* - * If we are unable to recycle an existing meta buffer - * signal the reclaim thread. It will notify users - * via the prune callback to drop references. The - * prune callback in run in the context of the reclaim - * thread to avoid deadlocking on the hash_lock. - * Of course, only do this when recycle is true. - */ - if (recycle) - cv_signal(&arc_reclaim_thr_cv); - } else { - ASSERT(type == ARC_BUFC_DATA); - buf->b_data = zio_data_buf_alloc(size); - arc_space_consume(size, ARC_SPACE_DATA); - } - - /* Only bump this if we tried to recycle and failed */ - if (recycle) - ARCSTAT_BUMP(arcstat_recycle_miss); - } - ASSERT(buf->b_data != NULL); -out: /* * Update the state size. Note that ghost states have a * "ghost size" and so don't need to be updated. @@ -3008,7 +3386,17 @@ out: arc_buf_hdr_t *hdr = buf->b_hdr; atomic_add_64(&hdr->b_l1hdr.b_state->arcs_size, size); - if (list_link_active(&hdr->b_l1hdr.b_arc_node)) { + + /* + * If this is reached via arc_read, the link is + * protected by the hash lock. If reached via + * arc_buf_alloc, the header should not be accessed by + * any other thread. And, if reached via arc_read_done, + * the hash lock will protect it if it's found in the + * hash table; otherwise no other thread should be + * trying to [add|remove]_reference it. + */ + if (multilist_link_active(&hdr->b_l1hdr.b_arc_node)) { ASSERT(refcount_is_zero(&hdr->b_l1hdr.b_refcnt)); atomic_add_64(&hdr->b_l1hdr.b_state->arcs_lsize[type], size); @@ -3017,8 +3405,7 @@ out: * If we are growing the cache, and we are adding anonymous * data, and we have outgrown arc_p, update arc_p */ - if (!zfs_arc_p_aggressive_disable && - arc_size < arc_c && hdr->b_l1hdr.b_state == arc_anon && + if (arc_size < arc_c && hdr->b_l1hdr.b_state == arc_anon && arc_anon->arcs_size + arc_mru->arcs_size > arc_p) arc_p = MIN(arc_c, arc_p + size); } @@ -3061,7 +3448,8 @@ arc_access(arc_buf_hdr_t *hdr, kmutex_t *hash_lock) */ if (HDR_PREFETCH(hdr)) { if (refcount_count(&hdr->b_l1hdr.b_refcnt) == 0) { - ASSERT(list_link_active( + /* link protected by hash lock */ + ASSERT(multilist_link_active( &hdr->b_l1hdr.b_arc_node)); } else { hdr->b_flags &= ~ARC_FLAG_PREFETCH; @@ -3125,7 +3513,8 @@ arc_access(arc_buf_hdr_t *hdr, kmutex_t *hash_lock) */ if ((HDR_PREFETCH(hdr)) != 0) { ASSERT(refcount_is_zero(&hdr->b_l1hdr.b_refcnt)); - ASSERT(list_link_active(&hdr->b_l1hdr.b_arc_node)); + /* link protected by hash_lock */ + ASSERT(multilist_link_active(&hdr->b_l1hdr.b_arc_node)); } atomic_inc_32(&hdr->b_l1hdr.b_mfu_hits); ARCSTAT_BUMP(arcstat_mfu_hits); @@ -3517,7 +3906,7 @@ top: ASSERT(GHOST_STATE(hdr->b_l1hdr.b_state)); ASSERT(!HDR_IO_IN_PROGRESS(hdr)); ASSERT(refcount_is_zero(&hdr->b_l1hdr.b_refcnt)); - ASSERT(hdr->b_l1hdr.b_buf == NULL); + ASSERT3P(hdr->b_l1hdr.b_buf, ==, NULL); /* if this is a prefetch, we don't have a reference */ if (*arc_flags & ARC_FLAG_PREFETCH) @@ -3813,7 +4202,7 @@ arc_clear_callback(arc_buf_t *buf) if (hdr->b_l1hdr.b_datacnt > 1) { mutex_exit(&buf->b_evict_lock); - arc_buf_destroy(buf, FALSE, TRUE); + arc_buf_destroy(buf, TRUE); } else { ASSERT(buf == hdr->b_l1hdr.b_buf); hdr->b_flags |= ARC_FLAG_BUF_AVAILABLE; @@ -3839,13 +4228,15 @@ arc_release(arc_buf_t *buf, void *tag) arc_buf_hdr_t *hdr = buf->b_hdr; /* - * It would be nice to assert that if it's DMU metadata (level > + * It would be nice to assert that if its DMU metadata (level > * 0 || it's the dnode file), then it must be syncing context. * But we don't know that information at this level. */ mutex_enter(&buf->b_evict_lock); + ASSERT(HDR_HAS_L1HDR(hdr)); + /* * We don't grab the hash lock prior to this check, because if * the buffer's header is in the arc_anon state, it won't be @@ -3892,6 +4283,13 @@ arc_release(arc_buf_t *buf, void *tag) mutex_enter(&hdr->b_l2hdr.b_dev->l2ad_mtx); list_remove(&hdr->b_l2hdr.b_dev->l2ad_buflist, hdr); + + /* + * We don't want to leak the b_tmp_cdata buffer that was + * allocated in l2arc_write_buffers() + */ + arc_buf_l2_cdata_free(hdr); + mutex_exit(&hdr->b_l2hdr.b_dev->l2ad_mtx); hdr->b_flags &= ~ARC_FLAG_HAS_L2HDR; @@ -3964,6 +4362,7 @@ arc_release(arc_buf_t *buf, void *tag) nhdr->b_l1hdr.b_datacnt = 1; nhdr->b_l1hdr.b_state = arc_anon; nhdr->b_l1hdr.b_arc_access = 0; + nhdr->b_l1hdr.b_tmp_cdata = NULL; nhdr->b_freeze_cksum = NULL; (void) refcount_add(&nhdr->b_l1hdr.b_refcnt, tag); @@ -3973,8 +4372,8 @@ arc_release(arc_buf_t *buf, void *tag) } else { mutex_exit(&buf->b_evict_lock); ASSERT(refcount_count(&hdr->b_l1hdr.b_refcnt) == 1); - /* protected by hash lock */ - ASSERT(!list_link_active(&hdr->b_l1hdr.b_arc_node)); + /* protected by hash lock, or hdr is on arc_anon */ + ASSERT(!multilist_link_active(&hdr->b_l1hdr.b_arc_node)); ASSERT(!HDR_IO_IN_PROGRESS(hdr)); hdr->b_l1hdr.b_mru_hits = 0; hdr->b_l1hdr.b_mru_ghost_hits = 0; @@ -4297,11 +4696,50 @@ arc_kstat_update(kstat_t *ksp, int rw) return (0); } +/* + * This function *must* return indices evenly distributed between all + * sublists of the multilist. This is needed due to how the ARC eviction + * code is laid out; arc_evict_state() assumes ARC buffers are evenly + * distributed between all sublists and uses this assumption when + * deciding which sublist to evict from and how much to evict from it. + */ +unsigned int +arc_state_multilist_index_func(multilist_t *ml, void *obj) +{ + arc_buf_hdr_t *hdr = obj; + + /* + * We rely on b_dva to generate evenly distributed index + * numbers using buf_hash below. So, as an added precaution, + * let's make sure we never add empty buffers to the arc lists. + */ + ASSERT(!BUF_EMPTY(hdr)); + + /* + * The assumption here, is the hash value for a given + * arc_buf_hdr_t will remain constant throughout its lifetime + * (i.e. its b_spa, b_dva, and b_birth fields don't change). + * Thus, we don't need to store the header's sublist index + * on insertion, as this index can be recalculated on removal. + * + * Also, the low order bits of the hash value are thought to be + * distributed evenly. Otherwise, in the case that the multilist + * has a power of two number of sublists, each sublists' usage + * would not be evenly distributed. + */ + return (buf_hash(hdr->b_spa, &hdr->b_dva, hdr->b_birth) % + multilist_get_num_sublists(ml)); +} + void arc_init(void) { - mutex_init(&arc_reclaim_thr_lock, NULL, MUTEX_DEFAULT, NULL); - cv_init(&arc_reclaim_thr_cv, NULL, CV_DEFAULT, NULL); + mutex_init(&arc_reclaim_lock, NULL, MUTEX_DEFAULT, NULL); + cv_init(&arc_reclaim_thread_cv, NULL, CV_DEFAULT, NULL); + cv_init(&arc_reclaim_waiters_cv, NULL, CV_DEFAULT, NULL); + + mutex_init(&arc_user_evicts_lock, NULL, MUTEX_DEFAULT, NULL); + cv_init(&arc_user_evicts_cv, NULL, CV_DEFAULT, NULL); /* Convert seconds to clock ticks */ zfs_arc_min_prefetch_lifespan = 1 * hz; @@ -4349,6 +4787,9 @@ arc_init(void) if (zfs_arc_meta_limit > 0 && zfs_arc_meta_limit <= arc_c_max) arc_meta_limit = zfs_arc_meta_limit; + if (zfs_arc_num_sublists_per_state < 1) + zfs_arc_num_sublists_per_state = num_online_cpus(); + /* if kmem_flags are set, lets try to use less memory */ if (kmem_debugging()) arc_c = arc_c / 2; @@ -4363,43 +4804,46 @@ arc_init(void) arc_l2c_only = &ARC_l2c_only; arc_size = 0; - mutex_init(&arc_anon->arcs_mtx, NULL, MUTEX_DEFAULT, NULL); - mutex_init(&arc_mru->arcs_mtx, NULL, MUTEX_DEFAULT, NULL); - mutex_init(&arc_mru_ghost->arcs_mtx, NULL, MUTEX_DEFAULT, NULL); - mutex_init(&arc_mfu->arcs_mtx, NULL, MUTEX_DEFAULT, NULL); - mutex_init(&arc_mfu_ghost->arcs_mtx, NULL, MUTEX_DEFAULT, NULL); - mutex_init(&arc_l2c_only->arcs_mtx, NULL, MUTEX_DEFAULT, NULL); - - list_create(&arc_mru->arcs_list[ARC_BUFC_METADATA], + multilist_create(&arc_mru->arcs_list[ARC_BUFC_METADATA], sizeof (arc_buf_hdr_t), - offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node)); - list_create(&arc_mru->arcs_list[ARC_BUFC_DATA], + offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node), + zfs_arc_num_sublists_per_state, arc_state_multilist_index_func); + multilist_create(&arc_mru->arcs_list[ARC_BUFC_DATA], sizeof (arc_buf_hdr_t), - offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node)); - list_create(&arc_mru_ghost->arcs_list[ARC_BUFC_METADATA], + offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node), + zfs_arc_num_sublists_per_state, arc_state_multilist_index_func); + multilist_create(&arc_mru_ghost->arcs_list[ARC_BUFC_METADATA], sizeof (arc_buf_hdr_t), - offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node)); - list_create(&arc_mru_ghost->arcs_list[ARC_BUFC_DATA], + offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node), + zfs_arc_num_sublists_per_state, arc_state_multilist_index_func); + multilist_create(&arc_mru_ghost->arcs_list[ARC_BUFC_DATA], sizeof (arc_buf_hdr_t), - offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node)); - list_create(&arc_mfu->arcs_list[ARC_BUFC_METADATA], + offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node), + zfs_arc_num_sublists_per_state, arc_state_multilist_index_func); + multilist_create(&arc_mfu->arcs_list[ARC_BUFC_METADATA], sizeof (arc_buf_hdr_t), - offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node)); - list_create(&arc_mfu->arcs_list[ARC_BUFC_DATA], + offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node), + zfs_arc_num_sublists_per_state, arc_state_multilist_index_func); + multilist_create(&arc_mfu->arcs_list[ARC_BUFC_DATA], sizeof (arc_buf_hdr_t), - offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node)); - list_create(&arc_mfu_ghost->arcs_list[ARC_BUFC_METADATA], + offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node), + zfs_arc_num_sublists_per_state, arc_state_multilist_index_func); + multilist_create(&arc_mfu_ghost->arcs_list[ARC_BUFC_METADATA], sizeof (arc_buf_hdr_t), - offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node)); - list_create(&arc_mfu_ghost->arcs_list[ARC_BUFC_DATA], + offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node), + zfs_arc_num_sublists_per_state, arc_state_multilist_index_func); + multilist_create(&arc_mfu_ghost->arcs_list[ARC_BUFC_DATA], sizeof (arc_buf_hdr_t), - offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node)); - list_create(&arc_l2c_only->arcs_list[ARC_BUFC_METADATA], + offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node), + zfs_arc_num_sublists_per_state, arc_state_multilist_index_func); + multilist_create(&arc_l2c_only->arcs_list[ARC_BUFC_METADATA], sizeof (arc_buf_hdr_t), - offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node)); - list_create(&arc_l2c_only->arcs_list[ARC_BUFC_DATA], + offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node), + zfs_arc_num_sublists_per_state, arc_state_multilist_index_func); + multilist_create(&arc_l2c_only->arcs_list[ARC_BUFC_DATA], sizeof (arc_buf_hdr_t), - offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node)); + offsetof(arc_buf_hdr_t, b_l1hdr.b_arc_node), + zfs_arc_num_sublists_per_state, arc_state_multilist_index_func); arc_anon->arcs_state = ARC_STATE_ANON; arc_mru->arcs_state = ARC_STATE_MRU; @@ -4410,12 +4854,12 @@ arc_init(void) buf_init(); - arc_thread_exit = 0; + arc_reclaim_thread_exit = FALSE; + arc_user_evicts_thread_exit = FALSE; list_create(&arc_prune_list, sizeof (arc_prune_t), offsetof(arc_prune_t, p_node)); arc_eviction_list = NULL; mutex_init(&arc_prune_mtx, NULL, MUTEX_DEFAULT, NULL); - mutex_init(&arc_eviction_mtx, NULL, MUTEX_DEFAULT, NULL); bzero(&arc_eviction_hdr, sizeof (arc_buf_hdr_t)); arc_ksp = kstat_create("zfs", 0, "arcstats", "misc", KSTAT_TYPE_NAMED, @@ -4430,6 +4874,9 @@ arc_init(void) (void) thread_create(NULL, 0, arc_adapt_thread, NULL, 0, &p0, TS_RUN, minclsyspri); + (void) thread_create(NULL, 0, arc_user_evicts_thread, NULL, 0, &p0, + TS_RUN, minclsyspri); + arc_dead = FALSE; arc_warm = B_FALSE; @@ -4458,17 +4905,36 @@ arc_fini(void) { arc_prune_t *p; - mutex_enter(&arc_reclaim_thr_lock); #ifdef _KERNEL spl_unregister_shrinker(&arc_shrinker); #endif /* _KERNEL */ - arc_thread_exit = 1; - while (arc_thread_exit != 0) - cv_wait(&arc_reclaim_thr_cv, &arc_reclaim_thr_lock); - mutex_exit(&arc_reclaim_thr_lock); + mutex_enter(&arc_reclaim_lock); + arc_reclaim_thread_exit = TRUE; + /* + * The reclaim thread will set arc_reclaim_thread_exit back to + * FALSE when it is finished exiting; we're waiting for that. + */ + while (arc_reclaim_thread_exit) { + cv_signal(&arc_reclaim_thread_cv); + cv_wait(&arc_reclaim_thread_cv, &arc_reclaim_lock); + } + mutex_exit(&arc_reclaim_lock); + + mutex_enter(&arc_user_evicts_lock); + arc_user_evicts_thread_exit = TRUE; + /* + * The user evicts thread will set arc_user_evicts_thread_exit + * to FALSE when it is finished exiting; we're waiting for that. + */ + while (arc_user_evicts_thread_exit) { + cv_signal(&arc_user_evicts_cv); + cv_wait(&arc_user_evicts_cv, &arc_user_evicts_lock); + } + mutex_exit(&arc_user_evicts_lock); - arc_flush(NULL); + /* Use TRUE to ensure *all* buffers are evicted */ + arc_flush(NULL, TRUE); arc_dead = TRUE; @@ -4488,25 +4954,23 @@ arc_fini(void) list_destroy(&arc_prune_list); mutex_destroy(&arc_prune_mtx); - mutex_destroy(&arc_eviction_mtx); - mutex_destroy(&arc_reclaim_thr_lock); - cv_destroy(&arc_reclaim_thr_cv); - - list_destroy(&arc_mru->arcs_list[ARC_BUFC_METADATA]); - list_destroy(&arc_mru_ghost->arcs_list[ARC_BUFC_METADATA]); - list_destroy(&arc_mfu->arcs_list[ARC_BUFC_METADATA]); - list_destroy(&arc_mfu_ghost->arcs_list[ARC_BUFC_METADATA]); - list_destroy(&arc_mru->arcs_list[ARC_BUFC_DATA]); - list_destroy(&arc_mru_ghost->arcs_list[ARC_BUFC_DATA]); - list_destroy(&arc_mfu->arcs_list[ARC_BUFC_DATA]); - list_destroy(&arc_mfu_ghost->arcs_list[ARC_BUFC_DATA]); - - mutex_destroy(&arc_anon->arcs_mtx); - mutex_destroy(&arc_mru->arcs_mtx); - mutex_destroy(&arc_mru_ghost->arcs_mtx); - mutex_destroy(&arc_mfu->arcs_mtx); - mutex_destroy(&arc_mfu_ghost->arcs_mtx); - mutex_destroy(&arc_l2c_only->arcs_mtx); + mutex_destroy(&arc_reclaim_lock); + cv_destroy(&arc_reclaim_thread_cv); + cv_destroy(&arc_reclaim_waiters_cv); + + mutex_destroy(&arc_user_evicts_lock); + cv_destroy(&arc_user_evicts_cv); + + multilist_destroy(&arc_mru->arcs_list[ARC_BUFC_METADATA]); + multilist_destroy(&arc_mru_ghost->arcs_list[ARC_BUFC_METADATA]); + multilist_destroy(&arc_mfu->arcs_list[ARC_BUFC_METADATA]); + multilist_destroy(&arc_mfu_ghost->arcs_list[ARC_BUFC_METADATA]); + multilist_destroy(&arc_mru->arcs_list[ARC_BUFC_DATA]); + multilist_destroy(&arc_mru_ghost->arcs_list[ARC_BUFC_DATA]); + multilist_destroy(&arc_mfu->arcs_list[ARC_BUFC_DATA]); + multilist_destroy(&arc_mfu_ghost->arcs_list[ARC_BUFC_DATA]); + multilist_destroy(&arc_l2c_only->arcs_list[ARC_BUFC_METADATA]); + multilist_destroy(&arc_l2c_only->arcs_list[ARC_BUFC_DATA]); buf_fini(); @@ -4835,34 +5299,62 @@ l2arc_write_done(zio_t *zio) if (zio->io_error != 0) ARCSTAT_BUMP(arcstat_l2_writes_error); - mutex_enter(&dev->l2ad_mtx); - /* * All writes completed, or an error was hit. */ +top: + mutex_enter(&dev->l2ad_mtx); for (hdr = list_prev(buflist, head); hdr; hdr = hdr_prev) { hdr_prev = list_prev(buflist, hdr); hash_lock = HDR_LOCK(hdr); + + /* + * We cannot use mutex_enter or else we can deadlock + * with l2arc_write_buffers (due to swapping the order + * the hash lock and l2ad_mtx are taken). + */ if (!mutex_tryenter(hash_lock)) { /* - * This buffer misses out. It may be in a stage - * of eviction. Its ARC_FLAG_L2_WRITING flag will be - * left set, denying reads to this buffer. + * Missed the hash lock. We must retry so we + * don't leave the ARC_FLAG_L2_WRITING bit set. */ - ARCSTAT_BUMP(arcstat_l2_writes_hdr_miss); - continue; + ARCSTAT_BUMP(arcstat_l2_writes_lock_retry); + + /* + * We don't want to rescan the headers we've + * already marked as having been written out, so + * we reinsert the head node so we can pick up + * where we left off. + */ + list_remove(buflist, head); + list_insert_after(buflist, hdr, head); + + mutex_exit(&dev->l2ad_mtx); + + /* + * We wait for the hash lock to become available + * to try and prevent busy waiting, and increase + * the chance we'll be able to acquire the lock + * the next time around. + */ + mutex_enter(hash_lock); + mutex_exit(hash_lock); + goto top; } /* - * It's possible that this buffer got evicted from the L1 cache - * before we grabbed the vdev + hash locks, in which case - * arc_hdr_realloc freed b_tmp_cdata for us if it was allocated. - * Only free the buffer if we still have an L1 hdr. + * We could not have been moved into the arc_l2c_only + * state while in-flight due to our ARC_FLAG_L2_WRITING + * bit being set. Let's just ensure that's being enforced. + */ + ASSERT(HDR_HAS_L1HDR(hdr)); + + /* + * We may have allocated a buffer for L2ARC compression, + * we must release it to avoid leaking this data. */ - if (HDR_HAS_L1HDR(hdr) && hdr->b_l1hdr.b_tmp_cdata != NULL && - HDR_GET_COMPRESS(hdr) != ZIO_COMPRESS_OFF) - l2arc_release_cdata_buf(hdr); + l2arc_release_cdata_buf(hdr); if (zio->io_error != 0) { /* @@ -4876,7 +5368,8 @@ l2arc_write_done(zio_t *zio) } /* - * Allow ARC to begin reads to this L2ARC entry. + * Allow ARC to begin reads and ghost list evictions to + * this L2ARC entry. */ hdr->b_flags &= ~ARC_FLAG_L2_WRITING; @@ -4984,35 +5477,37 @@ l2arc_read_done(zio_t *zio) * the data lists. This function returns a locked list, and also returns * the lock pointer. */ -static list_t * -l2arc_list_locked(int list_num, kmutex_t **lock) +static multilist_sublist_t * +l2arc_sublist_lock(int list_num) { - list_t *list = NULL; + multilist_t *ml = NULL; + unsigned int idx; ASSERT(list_num >= 0 && list_num <= 3); switch (list_num) { case 0: - list = &arc_mfu->arcs_list[ARC_BUFC_METADATA]; - *lock = &arc_mfu->arcs_mtx; + ml = &arc_mfu->arcs_list[ARC_BUFC_METADATA]; break; case 1: - list = &arc_mru->arcs_list[ARC_BUFC_METADATA]; - *lock = &arc_mru->arcs_mtx; + ml = &arc_mru->arcs_list[ARC_BUFC_METADATA]; break; case 2: - list = &arc_mfu->arcs_list[ARC_BUFC_DATA]; - *lock = &arc_mfu->arcs_mtx; + ml = &arc_mfu->arcs_list[ARC_BUFC_DATA]; break; case 3: - list = &arc_mru->arcs_list[ARC_BUFC_DATA]; - *lock = &arc_mru->arcs_mtx; + ml = &arc_mru->arcs_list[ARC_BUFC_DATA]; break; } - ASSERT(!(MUTEX_HELD(*lock))); - mutex_enter(*lock); - return (list); + /* + * Return a randomly-selected sublist. This is acceptable + * because the caller feeds only a little bit of data for each + * call (8MB). Subsequent calls will result in different + * sublists being selected. + */ + idx = multilist_get_random_index(ml); + return (multilist_sublist_lock(ml, idx)); } /* @@ -5058,6 +5553,12 @@ top: hdr_prev = list_prev(buflist, hdr); hash_lock = HDR_LOCK(hdr); + + /* + * We cannot use mutex_enter or else we can deadlock + * with l2arc_write_buffers (due to swapping the order + * the hash lock and l2ad_mtx are taken). + */ if (!mutex_tryenter(hash_lock)) { /* * Missed the hash lock. Retry. @@ -5122,8 +5623,9 @@ top: hdr->b_flags &= ~ARC_FLAG_HAS_L2HDR; list_remove(buflist, hdr); - /* This may have been leftover after a failed write. */ - hdr->b_flags &= ~ARC_FLAG_L2_WRITING; + /* Ensure this header has finished being written */ + ASSERT(!HDR_L2_WRITING(hdr)); + ASSERT3P(hdr->b_l1hdr.b_tmp_cdata, ==, NULL); } mutex_exit(hash_lock); } @@ -5149,11 +5651,9 @@ l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz, boolean_t *headroom_boost) { arc_buf_hdr_t *hdr, *hdr_prev, *head; - list_t *list; uint64_t write_asize, write_psize, write_sz, headroom, buf_compress_minsz; void *buf_data; - kmutex_t *list_lock = NULL; boolean_t full; l2arc_write_callback_t *cb; zio_t *pio, *wzio; @@ -5182,12 +5682,10 @@ l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz, /* * Copy buffers for L2ARC writing. */ - mutex_enter(&dev->l2ad_mtx); for (try = 0; try <= 3; try++) { + multilist_sublist_t *mls = l2arc_sublist_lock(try); uint64_t passed_sz = 0; - list = l2arc_list_locked(try, &list_lock); - /* * L2ARC fast warmup. * @@ -5195,9 +5693,9 @@ l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz, * head of the ARC lists rather than the tail. */ if (arc_warm == B_FALSE) - hdr = list_head(list); + hdr = multilist_sublist_head(mls); else - hdr = list_tail(list); + hdr = multilist_sublist_tail(mls); headroom = target_sz * l2arc_headroom; if (do_headroom_boost) @@ -5208,9 +5706,9 @@ l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz, uint64_t buf_sz; if (arc_warm == B_FALSE) - hdr_prev = list_next(list, hdr); + hdr_prev = multilist_sublist_next(mls, hdr); else - hdr_prev = list_prev(list, hdr); + hdr_prev = multilist_sublist_prev(mls, hdr); hash_lock = HDR_LOCK(hdr); if (!mutex_tryenter(hash_lock)) { @@ -5246,7 +5744,9 @@ l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz, * l2arc_write_done() can find where the * write buffers begin without searching. */ + mutex_enter(&dev->l2ad_mtx); list_insert_head(&dev->l2ad_buflist, head); + mutex_exit(&dev->l2ad_mtx); cb = kmem_alloc(sizeof (l2arc_write_callback_t), KM_SLEEP); @@ -5278,7 +5778,9 @@ l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz, buf_sz = hdr->b_size; hdr->b_flags |= ARC_FLAG_HAS_L2HDR; + mutex_enter(&dev->l2ad_mtx); list_insert_head(&dev->l2ad_buflist, hdr); + mutex_exit(&dev->l2ad_mtx); /* * Compute and store the buffer cksum before @@ -5292,7 +5794,7 @@ l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz, write_sz += buf_sz; } - mutex_exit(list_lock); + multilist_sublist_unlock(mls); if (full == B_TRUE) break; @@ -5301,12 +5803,13 @@ l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz, /* No buffers selected for writing? */ if (pio == NULL) { ASSERT0(write_sz); - mutex_exit(&dev->l2ad_mtx); ASSERT(!HDR_HAS_L1HDR(head)); kmem_cache_free(hdr_l2only_cache, head); return (0); } + mutex_enter(&dev->l2ad_mtx); + /* * Now start writing the buffers. We're starting at the write head * and work backwards, retracing the course of the buffer selector @@ -5317,6 +5820,14 @@ l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz, uint64_t buf_sz; /* + * We rely on the L1 portion of the header below, so + * it's invalid for this header to have been evicted out + * of the ghost cache, prior to being written out. The + * ARC_FLAG_L2_WRITING bit ensures this won't happen. + */ + ASSERT(HDR_HAS_L1HDR(hdr)); + + /* * We shouldn't need to lock the buffer here, since we flagged * it as ARC_FLAG_L2_WRITING in the previous step, but we must * take care to only access its L2 cache parameters. In @@ -5538,8 +6049,26 @@ l2arc_decompress_zio(zio_t *zio, arc_buf_hdr_t *hdr, enum zio_compress c) static void l2arc_release_cdata_buf(arc_buf_hdr_t *hdr) { + enum zio_compress comp = HDR_GET_COMPRESS(hdr); + ASSERT(HDR_HAS_L1HDR(hdr)); - if (HDR_GET_COMPRESS(hdr) != ZIO_COMPRESS_EMPTY) { + ASSERT(comp == ZIO_COMPRESS_OFF || L2ARC_IS_VALID_COMPRESS(comp)); + + if (comp == ZIO_COMPRESS_OFF) { + /* + * In this case, b_tmp_cdata points to the same buffer + * as the arc_buf_t's b_data field. We don't want to + * free it, since the arc_buf_t will handle that. + */ + hdr->b_l1hdr.b_tmp_cdata = NULL; + } else if (comp == ZIO_COMPRESS_EMPTY) { + /* + * In this case, b_tmp_cdata was compressed to an empty + * buffer, thus there's nothing to free and b_tmp_cdata + * should have been set to NULL in l2arc_write_buffers(). + */ + ASSERT3P(hdr->b_l1hdr.b_tmp_cdata, ==, NULL); + } else { /* * If the data was compressed, then we've allocated a * temporary buffer for it, so now we need to release it. @@ -5547,8 +6076,9 @@ l2arc_release_cdata_buf(arc_buf_hdr_t *hdr) ASSERT(hdr->b_l1hdr.b_tmp_cdata != NULL); zio_data_buf_free(hdr->b_l1hdr.b_tmp_cdata, hdr->b_size); + hdr->b_l1hdr.b_tmp_cdata = NULL; } - hdr->b_l1hdr.b_tmp_cdata = NULL; + } /* @@ -5834,6 +6364,9 @@ MODULE_PARM_DESC(zfs_arc_max, "Max arc size"); module_param(zfs_arc_meta_limit, ulong, 0644); MODULE_PARM_DESC(zfs_arc_meta_limit, "Meta limit for arc size"); +module_param(zfs_arc_meta_min, ulong, 0644); +MODULE_PARM_DESC(zfs_arc_meta_min, "Min arc metadata"); + module_param(zfs_arc_meta_prune, int, 0644); MODULE_PARM_DESC(zfs_arc_meta_prune, "Meta objects to scan for prune"); @@ -5865,6 +6398,10 @@ MODULE_PARM_DESC(zfs_arc_memory_throttle_disable, "disable memory throttle"); module_param(zfs_arc_min_prefetch_lifespan, int, 0644); MODULE_PARM_DESC(zfs_arc_min_prefetch_lifespan, "Min life of prefetch block"); +module_param(zfs_arc_num_sublists_per_state, int, 0644); +MODULE_PARM_DESC(zfs_arc_num_sublists_per_state, + "Number of sublists used in each of the ARC state lists"); + module_param(l2arc_write_max, ulong, 0644); MODULE_PARM_DESC(l2arc_write_max, "Max write bytes per interval"); diff --git a/module/zfs/dbuf_stats.c b/module/zfs/dbuf_stats.c index 5e7eaf1ac..afdf828ed 100644 --- a/module/zfs/dbuf_stats.c +++ b/module/zfs/dbuf_stats.c @@ -48,12 +48,12 @@ dbuf_stats_hash_table_headers(char *buf, size_t size) (void) snprintf(buf, size, "%-88s | %-124s | %s\n" "%-16s %-8s %-8s %-8s %-8s %-8s %-8s %-5s %-5s %5s | " - "%-5s %-5s %-6s %-8s %-6s %-8s %-12s " + "%-5s %-5s %-8s %-6s %-8s %-12s " "%-6s %-6s %-6s %-6s %-6s %-8s %-8s %-8s %-5s | " "%-6s %-6s %-8s %-8s %-6s %-6s %-5s %-8s %-8s\n", "dbuf", "arcbuf", "dnode", "pool", "objset", "object", "level", "blkid", "offset", "dbsize", "meta", "state", "dbholds", "list", - "atype", "index", "flags", "count", "asize", "access", + "atype", "flags", "count", "asize", "access", "mru", "gmru", "mfu", "gmfu", "l2", "l2_dattr", "l2_asize", "l2_comp", "aholds", "dtype", "btype", "data_bs", "meta_bs", "bsize", "lvls", "dholds", "blocks", "dsize"); @@ -77,7 +77,7 @@ __dbuf_stats_hash_table_data(char *buf, size_t size, dmu_buf_impl_t *db) nwritten = snprintf(buf, size, "%-16s %-8llu %-8lld %-8lld %-8lld %-8llu %-8llu %-5d %-5d %-5lu | " - "%-5d %-5d %-6lld 0x%-6x %-6lu %-8llu %-12llu " + "%-5d %-5d 0x%-6x %-6lu %-8llu %-12llu " "%-6lu %-6lu %-6lu %-6lu %-6lu %-8llu %-8llu %-8d %-5lu | " "%-6d %-6d %-8lu %-8lu %-6llu %-6lu %-5lu %-8llu %-8llu\n", /* dmu_buf_impl_t */ @@ -94,7 +94,6 @@ __dbuf_stats_hash_table_data(char *buf, size_t size, dmu_buf_impl_t *db) /* arc_buf_info_t */ abi.abi_state_type, abi.abi_state_contents, - (longlong_t)abi.abi_state_index, abi.abi_flags, (ulong_t)abi.abi_datacnt, (u_longlong_t)abi.abi_size, diff --git a/module/zfs/dsl_pool.c b/module/zfs/dsl_pool.c index 7d84d8bf4..108fc5299 100644 --- a/module/zfs/dsl_pool.c +++ b/module/zfs/dsl_pool.c @@ -317,7 +317,14 @@ dsl_pool_close(dsl_pool_t *dp) txg_list_destroy(&dp->dp_sync_tasks); txg_list_destroy(&dp->dp_dirty_dirs); - arc_flush(dp->dp_spa); + /* + * We can't set retry to TRUE since we're explicitly specifying + * a spa to flush. This is good enough; any missed buffers for + * this spa won't cause trouble, and they'll eventually fall + * out of the ARC just like any other unused buffer. + */ + arc_flush(dp->dp_spa, FALSE); + txg_fini(dp); dsl_scan_fini(dp); dmu_buf_user_evict_wait(); diff --git a/module/zfs/multilist.c b/module/zfs/multilist.c new file mode 100644 index 000000000..e4446ded2 --- /dev/null +++ b/module/zfs/multilist.c @@ -0,0 +1,375 @@ +/* + * CDDL HEADER START + * + * This file and its contents are supplied under the terms of the + * Common Development and Distribution License ("CDDL"), version 1.0. + * You may only use this file in accordance with the terms of version + * 1.0 of the CDDL. + * + * A full copy of the text of the CDDL should have accompanied this + * source. A copy of the CDDL is also available via the Internet at + * http://www.illumos.org/license/CDDL. + * + * CDDL HEADER END + */ +/* + * Copyright (c) 2013, 2014 by Delphix. All rights reserved. + */ + +#include <sys/zfs_context.h> +#include <sys/multilist.h> +#include <sys/trace_multilist.h> + +/* needed for spa_get_random() */ +#include <sys/spa.h> + +/* + * Given the object contained on the list, return a pointer to the + * object's multilist_node_t structure it contains. + */ +#ifdef DEBUG +static multilist_node_t * +multilist_d2l(multilist_t *ml, void *obj) +{ + return ((multilist_node_t *)((char *)obj + ml->ml_offset)); +} +#endif + +/* + * Initialize a new mutlilist using the parameters specified. + * + * - 'size' denotes the size of the structure containing the + * multilist_node_t. + * - 'offset' denotes the byte offset of the mutlilist_node_t within + * the structure that contains it. + * - 'num' specifies the number of internal sublists to create. + * - 'index_func' is used to determine which sublist to insert into + * when the multilist_insert() function is called; as well as which + * sublist to remove from when multilist_remove() is called. The + * requirements this function must meet, are the following: + * + * - It must always return the same value when called on the same + * object (to ensure the object is removed from the list it was + * inserted into). + * + * - It must return a value in the range [0, number of sublists). + * The multilist_get_num_sublists() function may be used to + * determine the number of sublists in the multilist. + * + * Also, in order to reduce internal contention between the sublists + * during insertion and removal, this function should choose evenly + * between all available sublists when inserting. This isn't a hard + * requirement, but a general rule of thumb in order to garner the + * best multi-threaded performance out of the data structure. + */ +void +multilist_create(multilist_t *ml, size_t size, size_t offset, unsigned int num, + multilist_sublist_index_func_t *index_func) +{ + int i; + + ASSERT3P(ml, !=, NULL); + ASSERT3U(size, >, 0); + ASSERT3U(size, >=, offset + sizeof (multilist_node_t)); + ASSERT3U(num, >, 0); + ASSERT3P(index_func, !=, NULL); + + ml->ml_offset = offset; + ml->ml_num_sublists = num; + ml->ml_index_func = index_func; + + ml->ml_sublists = kmem_zalloc(sizeof (multilist_sublist_t) * + ml->ml_num_sublists, KM_SLEEP); + + ASSERT3P(ml->ml_sublists, !=, NULL); + + for (i = 0; i < ml->ml_num_sublists; i++) { + multilist_sublist_t *mls = &ml->ml_sublists[i]; + mutex_init(&mls->mls_lock, NULL, MUTEX_DEFAULT, NULL); + list_create(&mls->mls_list, size, offset); + } +} + +/* + * Destroy the given multilist object, and free up any memory it holds. + */ +void +multilist_destroy(multilist_t *ml) +{ + int i; + + ASSERT(multilist_is_empty(ml)); + + for (i = 0; i < ml->ml_num_sublists; i++) { + multilist_sublist_t *mls = &ml->ml_sublists[i]; + + ASSERT(list_is_empty(&mls->mls_list)); + + list_destroy(&mls->mls_list); + mutex_destroy(&mls->mls_lock); + } + + ASSERT3P(ml->ml_sublists, !=, NULL); + kmem_free(ml->ml_sublists, + sizeof (multilist_sublist_t) * ml->ml_num_sublists); + + ml->ml_num_sublists = 0; + ml->ml_offset = 0; +} + +/* + * Insert the given object into the multilist. + * + * This function will insert the object specified into the sublist + * determined using the function given at multilist creation time. + * + * The sublist locks are automatically acquired if not already held, to + * ensure consistency when inserting and removing from multiple threads. + */ +void +multilist_insert(multilist_t *ml, void *obj) +{ + unsigned int sublist_idx = ml->ml_index_func(ml, obj); + multilist_sublist_t *mls; + boolean_t need_lock; + + DTRACE_PROBE3(multilist__insert, multilist_t *, ml, + unsigned int, sublist_idx, void *, obj); + + ASSERT3U(sublist_idx, <, ml->ml_num_sublists); + + mls = &ml->ml_sublists[sublist_idx]; + + /* + * Note: Callers may already hold the sublist lock by calling + * multilist_sublist_lock(). Here we rely on MUTEX_HELD() + * returning TRUE if and only if the current thread holds the + * lock. While it's a little ugly to make the lock recursive in + * this way, it works and allows the calling code to be much + * simpler -- otherwise it would have to pass around a flag + * indicating that it already has the lock. + */ + need_lock = !MUTEX_HELD(&mls->mls_lock); + + if (need_lock) + mutex_enter(&mls->mls_lock); + + ASSERT(!multilist_link_active(multilist_d2l(ml, obj))); + + multilist_sublist_insert_head(mls, obj); + + if (need_lock) + mutex_exit(&mls->mls_lock); +} + +/* + * Remove the given object from the multilist. + * + * This function will remove the object specified from the sublist + * determined using the function given at multilist creation time. + * + * The necessary sublist locks are automatically acquired, to ensure + * consistency when inserting and removing from multiple threads. + */ +void +multilist_remove(multilist_t *ml, void *obj) +{ + unsigned int sublist_idx = ml->ml_index_func(ml, obj); + multilist_sublist_t *mls; + boolean_t need_lock; + + DTRACE_PROBE3(multilist__remove, multilist_t *, ml, + unsigned int, sublist_idx, void *, obj); + + ASSERT3U(sublist_idx, <, ml->ml_num_sublists); + + mls = &ml->ml_sublists[sublist_idx]; + /* See comment in multilist_insert(). */ + need_lock = !MUTEX_HELD(&mls->mls_lock); + + if (need_lock) + mutex_enter(&mls->mls_lock); + + ASSERT(multilist_link_active(multilist_d2l(ml, obj))); + + multilist_sublist_remove(mls, obj); + + if (need_lock) + mutex_exit(&mls->mls_lock); +} + +/* + * Check to see if this multilist object is empty. + * + * This will return TRUE if it finds all of the sublists of this + * multilist to be empty, and FALSE otherwise. Each sublist lock will be + * automatically acquired as necessary. + * + * If concurrent insertions and removals are occurring, the semantics + * of this function become a little fuzzy. Instead of locking all + * sublists for the entire call time of the function, each sublist is + * only locked as it is individually checked for emptiness. Thus, it's + * possible for this function to return TRUE with non-empty sublists at + * the time the function returns. This would be due to another thread + * inserting into a given sublist, after that specific sublist was check + * and deemed empty, but before all sublists have been checked. + */ +int +multilist_is_empty(multilist_t *ml) +{ + int i; + + for (i = 0; i < ml->ml_num_sublists; i++) { + multilist_sublist_t *mls = &ml->ml_sublists[i]; + /* See comment in multilist_insert(). */ + boolean_t need_lock = !MUTEX_HELD(&mls->mls_lock); + + if (need_lock) + mutex_enter(&mls->mls_lock); + + if (!list_is_empty(&mls->mls_list)) { + if (need_lock) + mutex_exit(&mls->mls_lock); + + return (FALSE); + } + + if (need_lock) + mutex_exit(&mls->mls_lock); + } + + return (TRUE); +} + +/* Return the number of sublists composing this multilist */ +unsigned int +multilist_get_num_sublists(multilist_t *ml) +{ + return (ml->ml_num_sublists); +} + +/* Return a randomly selected, valid sublist index for this multilist */ +unsigned int +multilist_get_random_index(multilist_t *ml) +{ + return (spa_get_random(ml->ml_num_sublists)); +} + +/* Lock and return the sublist specified at the given index */ +multilist_sublist_t * +multilist_sublist_lock(multilist_t *ml, unsigned int sublist_idx) +{ + multilist_sublist_t *mls; + + ASSERT3U(sublist_idx, <, ml->ml_num_sublists); + mls = &ml->ml_sublists[sublist_idx]; + mutex_enter(&mls->mls_lock); + + return (mls); +} + +void +multilist_sublist_unlock(multilist_sublist_t *mls) +{ + mutex_exit(&mls->mls_lock); +} + +/* + * We're allowing any object to be inserted into this specific sublist, + * but this can lead to trouble if multilist_remove() is called to + * remove this object. Specifically, if calling ml_index_func on this + * object returns an index for sublist different than what is passed as + * a parameter here, any call to multilist_remove() with this newly + * inserted object is undefined! (the call to multilist_remove() will + * remove the object from a list that it isn't contained in) + */ +void +multilist_sublist_insert_head(multilist_sublist_t *mls, void *obj) +{ + ASSERT(MUTEX_HELD(&mls->mls_lock)); + list_insert_head(&mls->mls_list, obj); +} + +/* please see comment above multilist_sublist_insert_head */ +void +multilist_sublist_insert_tail(multilist_sublist_t *mls, void *obj) +{ + ASSERT(MUTEX_HELD(&mls->mls_lock)); + list_insert_tail(&mls->mls_list, obj); +} + +/* + * Move the object one element forward in the list. + * + * This function will move the given object forward in the list (towards + * the head) by one object. So, in essence, it will swap its position in + * the list with its "prev" pointer. If the given object is already at the + * head of the list, it cannot be moved forward any more than it already + * is, so no action is taken. + * + * NOTE: This function **must not** remove any object from the list other + * than the object given as the parameter. This is relied upon in + * arc_evict_state_impl(). + */ +void +multilist_sublist_move_forward(multilist_sublist_t *mls, void *obj) +{ + void *prev = list_prev(&mls->mls_list, obj); + + ASSERT(MUTEX_HELD(&mls->mls_lock)); + ASSERT(!list_is_empty(&mls->mls_list)); + + /* 'obj' must be at the head of the list, nothing to do */ + if (prev == NULL) + return; + + list_remove(&mls->mls_list, obj); + list_insert_before(&mls->mls_list, prev, obj); +} + +void +multilist_sublist_remove(multilist_sublist_t *mls, void *obj) +{ + ASSERT(MUTEX_HELD(&mls->mls_lock)); + list_remove(&mls->mls_list, obj); +} + +void * +multilist_sublist_head(multilist_sublist_t *mls) +{ + ASSERT(MUTEX_HELD(&mls->mls_lock)); + return (list_head(&mls->mls_list)); +} + +void * +multilist_sublist_tail(multilist_sublist_t *mls) +{ + ASSERT(MUTEX_HELD(&mls->mls_lock)); + return (list_tail(&mls->mls_list)); +} + +void * +multilist_sublist_next(multilist_sublist_t *mls, void *obj) +{ + ASSERT(MUTEX_HELD(&mls->mls_lock)); + return (list_next(&mls->mls_list, obj)); +} + +void * +multilist_sublist_prev(multilist_sublist_t *mls, void *obj) +{ + ASSERT(MUTEX_HELD(&mls->mls_lock)); + return (list_prev(&mls->mls_list, obj)); +} + +void +multilist_link_init(multilist_node_t *link) +{ + list_link_init(link); +} + +int +multilist_link_active(multilist_node_t *link) +{ + return (list_link_active(link)); +} diff --git a/module/zfs/trace.c b/module/zfs/trace.c index 470cf18bf..0c9990e85 100644 --- a/module/zfs/trace.c +++ b/module/zfs/trace.c @@ -23,6 +23,7 @@ * (and only one) C file, so this dummy file exists for that purpose. */ +#include <sys/multilist.h> #include <sys/arc_impl.h> #include <sys/vdev_impl.h> #include <sys/zio.h> @@ -31,6 +32,7 @@ #include <sys/dsl_dataset.h> #include <sys/dmu_tx.h> #include <sys/dnode.h> +#include <sys/multilist.h> #include <sys/zfs_znode.h> #include <sys/zil_impl.h> #include <sys/zrlock.h> @@ -42,6 +44,7 @@ #include <sys/trace_dbuf.h> #include <sys/trace_dmu.h> #include <sys/trace_dnode.h> +#include <sys/trace_multilist.h> #include <sys/trace_txg.h> #include <sys/trace_zil.h> #include <sys/trace_zrlock.h> diff --git a/module/zfs/zio_inject.c b/module/zfs/zio_inject.c index 5afb23c59..40b507a0b 100644 --- a/module/zfs/zio_inject.c +++ b/module/zfs/zio_inject.c @@ -439,7 +439,11 @@ zio_inject_fault(char *name, int flags, int *id, zinject_record_t *record) * fault injection isn't a performance critical path. */ if (flags & ZINJECT_FLUSH_ARC) - arc_flush(NULL); + /* + * We must use FALSE to ensure arc_flush returns, since + * we're not preventing concurrent ARC insertions. + */ + arc_flush(NULL, FALSE); return (0); } |