Illumos 5987 - zfs prefetch code needs work

5987 zfs prefetch code needs work
Reviewed by: Adam Leventhal <[email protected]>
Reviewed by: George Wilson <[email protected]>
Reviewed by: Paul Dagnelie <[email protected]>
Approved by: Gordon Ross <[email protected]>

References:
  https://www.illumos.org/issues/5987 zfs prefetch code needs work
  illumos/illumos-gate@cf6106c 5987 zfs prefetch code needs work

Porting notes:
- [module/zfs/dbuf.c]
  - 5f6d0b6 Handle block pointers with a corrupt logical size
- [module/zfs/dmu_zfetch.c]
  - c65aa5b Fix gcc missing parenthesis warnings
  - 428870f Update core ZFS code from build 121 to build 141.
  - 79c76d5 Change KM_PUSHPAGE -> KM_SLEEP
  - b8d06fc Switch KM_SLEEP to KM_PUSHPAGE
  - Account for ISO C90 - mixed declarations and code - warnings
  - Module parameters (new/changed):
    - Replaced zfetch_block_cap with zfetch_max_distance
      (Max bytes to prefetch per stream (default 8MB; 8 * 1024 * 1024))
    - Preserved zfs_prefetch_disable as 'int' for consistency with
      existing Linux module options.
- [include/sys/trace_arc.h]
  - Added new tracepoints
    - DEFINE_ARC_BUF_HDR_EVENT(zfs_arc__sync__wait__for__async);
    - DEFINE_ARC_BUF_HDR_EVENT(zfs_arc__demand__hit__predictive__prefetch);
- [man/man5/zfs-module-parameters.5]
  - Updated man page

Ported-by: kernelOfTruth [email protected]
Signed-off-by: Brian Behlendorf <[email protected]>

1 files changed, 16 insertions, 12 deletions

diff --git a/include/sys/arc.h b/include/sys/arc.h
index db7a64aa2..5780554b5 100644
--- a/include/sys/arc.h
+++ b/include/sys/arc.h
@@ -84,27 +84,31 @@ typedef enum arc_flags
 	ARC_FLAG_CACHED			= 1 << 4,	/* I/O was in cache */
 	ARC_FLAG_L2CACHE		= 1 << 5,	/* cache in L2ARC */
 	ARC_FLAG_L2COMPRESS		= 1 << 6,	/* compress in L2ARC */
+	ARC_FLAG_PREDICTIVE_PREFETCH	= 1 << 7,	/* I/O from zfetch */
 
 	/*
 	 * Private ARC flags.  These flags are private ARC only flags that
 	 * will show up in b_flags in the arc_hdr_buf_t. These flags should
 	 * only be set by ARC code.
 	 */
-	ARC_FLAG_IN_HASH_TABLE		= 1 << 7,	/* buffer is hashed */
-	ARC_FLAG_IO_IN_PROGRESS		= 1 << 8,	/* I/O in progress */
-	ARC_FLAG_IO_ERROR		= 1 << 9,	/* I/O failed for buf */
-	ARC_FLAG_FREED_IN_READ		= 1 << 10,	/* freed during read */
-	ARC_FLAG_BUF_AVAILABLE		= 1 << 11,	/* block not in use */
-	ARC_FLAG_INDIRECT		= 1 << 12,	/* indirect block */
-	ARC_FLAG_L2_WRITING		= 1 << 13,	/* write in progress */
-	ARC_FLAG_L2_EVICTED		= 1 << 14,	/* evicted during I/O */
-	ARC_FLAG_L2_WRITE_HEAD		= 1 << 15,	/* head of write list */
+	ARC_FLAG_IN_HASH_TABLE		= 1 << 8,	/* buffer is hashed */
+	ARC_FLAG_IO_IN_PROGRESS		= 1 << 9,	/* I/O in progress */
+	ARC_FLAG_IO_ERROR		= 1 << 10,	/* I/O failed for buf */
+	ARC_FLAG_FREED_IN_READ		= 1 << 11,	/* freed during read */
+	ARC_FLAG_BUF_AVAILABLE		= 1 << 12,	/* block not in use */
+	ARC_FLAG_INDIRECT		= 1 << 13,	/* indirect block */
+	/* Indicates that block was read with ASYNC priority. */
+	ARC_FLAG_PRIO_ASYNC_READ	= 1 << 14,
+	ARC_FLAG_L2_WRITING		= 1 << 15,	/* write in progress */
+	ARC_FLAG_L2_EVICTED		= 1 << 16,	/* evicted during I/O */
+	ARC_FLAG_L2_WRITE_HEAD		= 1 << 17,	/* head of write list */
 	/* indicates that the buffer contains metadata (otherwise, data) */
-	ARC_FLAG_BUFC_METADATA		= 1 << 16,
+	ARC_FLAG_BUFC_METADATA		= 1 << 18,
 
 	/* Flags specifying whether optional hdr struct fields are defined */
-	ARC_FLAG_HAS_L1HDR		= 1 << 17,
-	ARC_FLAG_HAS_L2HDR		= 1 << 18,
+	ARC_FLAG_HAS_L1HDR		= 1 << 19,
+	ARC_FLAG_HAS_L2HDR		= 1 << 20,
+
 } arc_flags_t;
 
 struct arc_buf {