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* Cleanup: Specify unsignedness on things that should not be signedRichard Yao2022-09-271-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In #13871, zfs_vdev_aggregation_limit_non_rotating and zfs_vdev_aggregation_limit being signed was pointed out as a possible reason not to eliminate an unnecessary MAX(unsigned, 0) since the unsigned value was assigned from them. There is no reason for these module parameters to be signed and upon inspection, it was found that there are a number of other module parameters that are signed, but should not be, so we make them unsigned. Making them unsigned made it clear that some other variables in the code should also be unsigned, so we also make those unsigned. This prevents users from setting negative values that could potentially cause bad behaviors. It also makes the code slightly easier to understand. Mostly module parameters that deal with timeouts, limits, bitshifts and percentages are made unsigned by this. Any that are boolean are left signed, since whether booleans should be considered signed or unsigned does not matter. Making zfs_arc_lotsfree_percent unsigned caused a `zfs_arc_lotsfree_percent >= 0` check to become redundant, so it was removed. Removing the check was also necessary to prevent a compiler error from -Werror=type-limits. Several end of line comments had to be moved to their own lines because replacing int with uint_t caused us to exceed the 80 character limit enforced by cstyle.pl. The following were kept signed because they are passed to taskq_create(), which expects signed values and modifying the OpenSolaris/Illumos DDI is out of scope of this patch: * metaslab_load_pct * zfs_sync_taskq_batch_pct * zfs_zil_clean_taskq_nthr_pct * zfs_zil_clean_taskq_minalloc * zfs_zil_clean_taskq_maxalloc * zfs_arc_prune_task_threads Also, negative values in those parameters was found to be harmless. The following were left signed because either negative values make sense, or more analysis was needed to determine whether negative values should be disallowed: * zfs_metaslab_switch_threshold * zfs_pd_bytes_max * zfs_livelist_min_percent_shared zfs_multihost_history was made static to be consistent with other parameters. A number of module parameters were marked as signed, but in reality referenced unsigned variables. upgrade_errlog_limit is one of the numerous examples. In the case of zfs_vdev_async_read_max_active, it was already uint32_t, but zdb had an extern int declaration for it. Interestingly, the documentation in zfs.4 was right for upgrade_errlog_limit despite the module parameter being wrongly marked, while the documentation for zfs_vdev_async_read_max_active (and friends) was wrong. It was also wrong for zstd_abort_size, which was unsigned, but was documented as signed. Also, the documentation in zfs.4 incorrectly described the following parameters as ulong when they were int: * zfs_arc_meta_adjust_restarts * zfs_override_estimate_recordsize They are now uint_t as of this patch and thus the man page has been updated to describe them as uint. dbuf_state_index was left alone since it does nothing and perhaps should be removed in another patch. If any module parameters were missed, they were not found by `grep -r 'ZFS_MODULE_PARAM' | grep ', INT'`. I did find a few that grep missed, but only because they were in files that had hits. This patch intentionally did not attempt to address whether some of these module parameters should be elevated to 64-bit parameters, because the length of a long on 32-bit is 32-bit. Lastly, it was pointed out during review that uint_t is a better match for these variables than uint32_t because FreeBSD kernel parameter definitions are designed for uint_t, whose bit width can change in future memory models. As a result, we change the existing parameters that are uint32_t to use uint_t. Reviewed-by: Alexander Motin <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Neal Gompa <[email protected]> Signed-off-by: Richard Yao <[email protected]> Closes #13875
* Replace dead opensolaris.org license linkTino Reichardt2022-07-111-1/+1
| | | | | | | | | The commit replaces all findings of the link: http://www.opensolaris.org/os/licensing with this one: https://opensource.org/licenses/CDDL-1.0 Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Tino Reichardt <[email protected]> Closes #13619
* Remaining {=> const} char|void *tagнаб2022-06-291-4/+4
| | | | | | Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Ahelenia Ziemiańska <[email protected]> Closes #13348
* Enable -Wwrite-stringsнаб2022-06-291-3/+3
| | | | | | | | Also, fix leak from ztest_global_vars_to_zdb_args() Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Ahelenia Ziemiańska <[email protected]> Closes #13348
* include: sys/arc.h: shim out arc_referenced()наб2021-12-231-0/+2
| | | | | | Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Ahelenia Ziemiańska <[email protected]> Closes #12844
* Introduce a tunable to exclude special class buffers from L2ARCGeorge Amanakis2021-11-111-0/+1
| | | | | | | | | | | Special allocation class or dedup vdevs may have roughly the same performance as L2ARC vdevs. Introduce a new tunable to exclude those buffers from being cacheable on L2ARC. Reviewed-by: Don Brady <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: George Amanakis <[email protected]> Closes #11761 Closes #12285
* Restore FreeBSD sysctl processing for arc.min and arc.maxAllan Jude2021-08-161-0/+7
| | | | | | | | | | | | | | | | Before OpenZFS 2.0, trying to set the FreeBSD sysctl vfs.zfs.arc_max to a disallowed value would return an error. Since the switch, it instead only generates WARN_IF_TUNING_IGNORED Keep the ability to set the sysctl's specifically to 0, even though that is less than the minimum, because some tests depend on this. Also lost, was the ability to set vfs.zfs.arc_max to a value less than the default vfs.zfs.arc_min at boot time. Restore this as well. Reviewed-by: Tony Nguyen <[email protected]> Reviewed-by: Ryan Moeller <[email protected]> Signed-off-by: Allan Jude <[email protected]> Closes #12161
* Remove NOTE(CONSTCOND) and note.hнаб2021-07-261-2/+2
| | | | | | | | These were mostly used to annotate do {} while(0)s Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Ahelenia Ziemiańska <[email protected]> Issue #12201
* Minor ARC optimizationsAlexander Motin2021-07-201-1/+1
| | | | | | | | | | | | | | | Remove unneeded global, practically constant, state pointer variables (arc_anon, arc_mru, etc.), replacing them with macros of real state variables addresses (&ARC_anon, &ARC_mru, etc.). Change ARC_EVICT_ALL from -1ULL to UINT64_MAX, not requiring special handling in inner loop of ARC reclamation. Respectively change bytes argument of arc_evict_state() from int64_t to uint64_t. Reviewed-by: Matthew Ahrens <[email protected]> Reviewed-by: Mark Maybee <[email protected]> Reviewed-by: Ryan Moeller <[email protected]> Signed-off-by: Alexander Motin <[email protected]> Closes #12348
* Implement memory and CPU hotplugPaul Dagnelie2020-12-101-0/+1
| | | | | | | | | | | | | | ZFS currently doesn't react to hotplugging cpu or memory into the system in any way. This patch changes that by adding logic to the ARC that allows the system to take advantage of new memory that is added for caching purposes. It also adds logic to the taskq infrastructure to support dynamically expanding the number of threads allocated to a taskq. Reviewed-by: Brian Behlendorf <[email protected]> Co-authored-by: Matthew Ahrens <[email protected]> Co-authored-by: Brian Behlendorf <[email protected]> Signed-off-by: Paul Dagnelie <[email protected]> Closes #11212
* Decouple arc_read_done callback from arc buf instantiationMatthew Macy2020-12-091-0/+5
| | | | | | | | | | | | Add ARC_FLAG_NO_BUF to indicate that a buffer need not be instantiated. This fixes a ~20% performance regression on cached reads due to zfetch changes. Reviewed-by: Tony Nguyen <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Matthew Ahrens <[email protected]> Signed-off-by: Matt Macy <[email protected]> Closes #11220 Closes #11232
* Add zstd support to zfsMichael Niewöhner2020-08-201-4/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This PR adds two new compression types, based on ZStandard: - zstd: A basic ZStandard compression algorithm Available compression. Levels for zstd are zstd-1 through zstd-19, where the compression increases with every level, but speed decreases. - zstd-fast: A faster version of the ZStandard compression algorithm zstd-fast is basically a "negative" level of zstd. The compression decreases with every level, but speed increases. Available compression levels for zstd-fast: - zstd-fast-1 through zstd-fast-10 - zstd-fast-20 through zstd-fast-100 (in increments of 10) - zstd-fast-500 and zstd-fast-1000 For more information check the man page. Implementation details: Rather than treat each level of zstd as a different algorithm (as was done historically with gzip), the block pointer `enum zio_compress` value is simply zstd for all levels, including zstd-fast, since they all use the same decompression function. The compress= property (a 64bit unsigned integer) uses the lower 7 bits to store the compression algorithm (matching the number of bits used in a block pointer, as the 8th bit was borrowed for embedded block pointers). The upper bits are used to store the compression level. It is necessary to be able to determine what compression level was used when later reading a block back, so the concept used in LZ4, where the first 32bits of the on-disk value are the size of the compressed data (since the allocation is rounded up to the nearest ashift), was extended, and we store the version of ZSTD and the level as well as the compressed size. This value is returned when decompressing a block, so that if the block needs to be recompressed (L2ARC, nop-write, etc), that the same parameters will be used to result in the matching checksum. All of the internal ZFS code ( `arc_buf_hdr_t`, `objset_t`, `zio_prop_t`, etc.) uses the separated _compress and _complevel variables. Only the properties ZAP contains the combined/bit-shifted value. The combined value is split when the compression_changed_cb() callback is called, and sets both objset members (os_compress and os_complevel). The userspace tools all use the combined/bit-shifted value. Additional notes: zdb can now also decode the ZSTD compression header (flag -Z) and inspect the size, version and compression level saved in that header. For each record, if it is ZSTD compressed, the parameters of the decoded compression header get printed. ZSTD is included with all current tests and new tests are added as-needed. Per-dataset feature flags now get activated when the property is set. If a compression algorithm requires a feature flag, zfs activates the feature when the property is set, rather than waiting for the first block to be born. This is currently only used by zstd but can be extended as needed. Portions-Sponsored-By: The FreeBSD Foundation Co-authored-by: Allan Jude <[email protected]> Co-authored-by: Brian Behlendorf <[email protected]> Co-authored-by: Sebastian Gottschall <[email protected]> Co-authored-by: Kjeld Schouten-Lebbing <[email protected]> Co-authored-by: Michael Niewöhner <[email protected]> Signed-off-by: Allan Jude <[email protected]> Signed-off-by: Allan Jude <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Signed-off-by: Sebastian Gottschall <[email protected]> Signed-off-by: Kjeld Schouten-Lebbing <[email protected]> Signed-off-by: Michael Niewöhner <[email protected]> Closes #6247 Closes #9024 Closes #10277 Closes #10278
* Include scatter_chunk_waste in arc_sizeMatthew Ahrens2020-08-171-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The ARC caches data in scatter ABD's, which are collections of pages, which are typically 4K. Therefore, the space used to cache each block is rounded up to a multiple of 4K. The ABD subsystem tracks this wasted memory in the `scatter_chunk_waste` kstat. However, the ARC's `size` is not aware of the memory used by this round-up, it only accounts for the size that it requested from the ABD subsystem. Therefore, the ARC is effectively using more memory than it is aware of, due to the `scatter_chunk_waste`. This impacts observability, e.g. `arcstat` will show that the ARC is using less memory than it effectively is. It also impacts how the ARC responds to memory pressure. As the amount of `scatter_chunk_waste` changes, it appears to the ARC as memory pressure, so it needs to resize `arc_c`. If the sector size (`1<<ashift`) is the same as the page size (or larger), there won't be any waste. If the (compressed) block size is relatively large compared to the page size, the amount of `scatter_chunk_waste` will be small, so the problematic effects are minimal. However, if using 512B sectors (`ashift=9`), and the (compressed) block size is small (e.g. `compression=on` with the default `volblocksize=8k` or a decreased `recordsize`), the amount of `scatter_chunk_waste` can be very large. On a production system, with `arc_size` at a constant 50% of memory, `scatter_chunk_waste` has been been observed to be 10-30% of memory. This commit adds `scatter_chunk_waste` to `arc_size`, and adds a new `waste` field to `arcstat`. As a result, the ARC's memory usage is more observable, and `arc_c` does not need to be adjusted as frequently. Reviewed-by: Pavel Zakharov <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: George Wilson <[email protected]> Reviewed-by: Ryan Moeller <[email protected]> Signed-off-by: Matthew Ahrens <[email protected]> Closes #10701
* Rename refcount.h to zfs_refcount.hMatthew Macy2020-07-291-1/+1
| | | | | | | | | Renamed to avoid conflicting with refcount.h when a different implementation is already provided by the platform. Reviewed-by: Ryan Moeller <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Matt Macy <[email protected]> Closes #10620
* Improve compatibility with C++ consumersRyan Moeller2020-06-061-6/+6
| | | | | | | | | C++ is a little picky about not using keywords for names, or string constness. Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Jorgen Lundman <[email protected]> Signed-off-by: Ryan Moeller <[email protected]> Closes #10409
* Persistent L2ARCGeorge Amanakis2020-04-101-0/+4
| | | | | | | | | | | | | | | | | | | | | This commit makes the L2ARC persistent across reboots. We implement a light-weight persistent L2ARC metadata structure that allows L2ARC contents to be recovered after a reboot. This significantly eases the impact a reboot has on read performance on systems with large caches. Reviewed-by: Matthew Ahrens <[email protected]> Reviewed-by: George Wilson <[email protected]> Reviewed-by: Ryan Moeller <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Co-authored-by: Saso Kiselkov <[email protected]> Co-authored-by: Jorgen Lundman <[email protected]> Co-authored-by: George Amanakis <[email protected]> Ported-by: Yuxuan Shui <[email protected]> Signed-off-by: George Amanakis <[email protected]> Closes #925 Closes #1823 Closes #2672 Closes #3744 Closes #9582
* Let default arc_c_max be platform dependentRyan Moeller2020-03-271-0/+1
| | | | | | | | | | | | Linux changed the default max ARC size to 1/2 of physical memory to deal with shortcomings of the Linux SLUB allocator. Other platforms do not require the same logic. Implement an arc_default_max() function to determine a default max ARC size in platform code. Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Ryan Moeller <[email protected]> Closes #10155
* Improve zfs send performance by bypassing the ARCMatthew Ahrens2020-03-101-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When doing a zfs send on a dataset with small recordsize (e.g. 8K), performance is dominated by the per-block overheads. This is especially true with `zfs send --compressed`, which further reduces the amount of data sent, for the same number of blocks. Several threads are involved, but the limiting factor is the `send_prefetch` thread, which is 100% on CPU. The main job of the `send_prefetch` thread is to issue zio's for the data that will be needed by the main thread. It does this by calling `arc_read(ARC_FLAG_PREFETCH)`. This has an immediate cost of creating an arc_hdr, which takes around 14% of one CPU. It also induces later costs by other threads: * Since the data was only prefetched, dmu_send()->dmu_dump_write() will need to call arc_read() again to get the data. This will have to look up the arc_hdr in the hash table and copy the data from the scatter ABD in the arc_hdr to a linear ABD in arc_buf. This takes 27% of one CPU. * dmu_dump_write() needs to arc_buf_destroy() This takes 11% of one CPU. * arc_adjust() will need to evict this arc_hdr, taking about 50% of one CPU. All of these costs can be avoided by bypassing the ARC if the data is not already cached. This commit changes `zfs send` to check for the data in the ARC, and if it is not found then we directly call `zio_read()`, reading the data into a linear ABD which is used by dmu_dump_write() directly. The performance improvement is best expressed in terms of how many blocks can be processed by `zfs send` in one second. This change increases the metric by 50%, from ~100,000 to ~150,000. When the amount of data per block is small (e.g. 2KB), there is a corresponding reduction in the elapsed time of `zfs send >/dev/null` (from 86 minutes to 58 minutes in this test case). In addition to improving the performance of `zfs send`, this change makes `zfs send` not pollute the ARC cache. In most cases the data will not be reused, so this allows us to keep caching useful data in the MRU (hit-once) part of the ARC. Reviewed-by: Paul Dagnelie <[email protected]> Reviewed-by: Serapheim Dimitropoulos <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Matthew Ahrens <[email protected]> Closes #10067
* Fix typos in include/Andrea Gelmini2019-08-301-1/+1
| | | | | | | Reviewed-by: Ryan Moeller <[email protected]> Reviewed-by: Richard Laager <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Andrea Gelmini <[email protected]> Closes #9238
* Cap metaslab memory usagePaul Dagnelie2019-08-161-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | On systems with large amounts of storage and high fragmentation, a huge amount of space can be used by storing metaslab range trees. Since metaslabs are only unloaded during a txg sync, and only if they have been inactive for 8 txgs, it is possible to get into a state where all of the system's memory is consumed by range trees and metaslabs, and txgs cannot sync. While ZFS knows how to evict ARC data when needed, it has no such mechanism for range tree data. This can result in boot hangs for some system configurations. First, we add the ability to unload metaslabs outside of syncing context. Second, we store a multilist of all loaded metaslabs, sorted by their selection txg, so we can quickly identify the oldest metaslabs. We use a multilist to reduce lock contention during heavy write workloads. Finally, we add logic that will unload a metaslab when we're loading a new metaslab, if we're using more than a certain fraction of the available memory on range trees. Reviewed-by: Matt Ahrens <[email protected]> Reviewed-by: George Wilson <[email protected]> Reviewed-by: Sebastien Roy <[email protected]> Reviewed-by: Serapheim Dimitropoulos <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Paul Dagnelie <[email protected]> Closes #9128
* Linux 4.19-rc3+ compat: Remove refcount_t compatTim Schumacher2018-09-261-1/+1
| | | | | | | | | | | | | | | torvalds/linux@59b57717f ("blkcg: delay blkg destruction until after writeback has finished") added a refcount_t to the blkcg structure. Due to the refcount_t compatibility code, zfs_refcount_t was used by mistake. Resolve this by removing the compatibility code and replacing the occurrences of refcount_t with zfs_refcount_t. Reviewed-by: Franz Pletz <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Tim Schumacher <[email protected]> Closes #7885 Closes #7932
* OpenZFS 9465 - ARC check for 'anon_size > arc_c/2' can stall the systemDon Brady2018-07-301-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | In the case of one pool being built on another pool, we want to make sure we don't end up throttling the lower (backing) pool when the upper pool is the majority contributor to dirty data. To insure we make forward progress during throttling, we also check the current pool's net dirty data and only throttle if it exceeds zfs_arc_pool_dirty_percent of the anonymous dirty data in the cache. Authored by: Don Brady <[email protected]> Reviewed by: Sebastien Roy <[email protected]> Reviewed by: Matt Ahrens <[email protected]> Reviewed by: Prashanth Sreenivasa <[email protected]> Approved by: Robert Mustacchi <[email protected]> Ported-by: Brian Behlendorf <[email protected]> Porting Notes: * The new global variables zfs_arc_dirty_limit_percent, zfs_arc_anon_limit_percent, and zfs_arc_pool_dirty_percent were intentially not added as tunable module parameters. OpenZFS-issue: https://illumos.org/issues/9465 OpenZFS-commit: https://github.com/openzfs/openzfs/commit/d6a4c3ef Closes #7749
* Decryption error handling improvementsTom Caputi2018-03-311-1/+1
| | | | | | | | | | | | | | | | | | Currently, the decryption and block authentication code in the ZIO / ARC layers is a bit inconsistent with regards to the ereports that are produces and the error codes that are passed to calling functions. This patch ensures that all of these errors (which begin as ECKSUM) are converted to EIO before they leave the ZIO or ARC layer and that ereports are correctly generated on each decryption / authentication failure. In addition, this patch fixes a bug in zio_decrypt() where ECKSUM never gets written to zio->io_error. Reviewed by: Matt Ahrens <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Tom Caputi <[email protected]> Closes #7372
* Fix ARC hit rateBrian Behlendorf2018-01-081-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | When the compressed ARC feature was added in commit d3c2ae1 the method of reference counting in the ARC was modified. As part of this accounting change the arc_buf_add_ref() function was removed entirely. This would have be fine but the arc_buf_add_ref() function served a second undocumented purpose of updating the ARC access information when taking a hold on a dbuf. Without this logic in place a cached dbuf would not migrate its associated arc_buf_hdr_t to the MFU list. This would negatively impact the ARC hit rate, particularly on systems with a small ARC. This change reinstates the missing call to arc_access() from dbuf_hold() by implementing a new arc_buf_access() function. Reviewed-by: Giuseppe Di Natale <[email protected]> Reviewed-by: Tony Hutter <[email protected]> Reviewed-by: Tim Chase <[email protected]> Reviewed by: George Wilson <[email protected]> Reviewed-by: George Melikov <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #6171 Closes #6852 Closes #6989
* Sequential scrub and resilversTom Caputi2017-11-151-19/+20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, scrubs and resilvers can take an extremely long time to complete. This is largely due to the fact that zfs scans process pools in logical order, as determined by each block's bookmark. This makes sense from a simplicity perspective, but blocks in zfs are often scattered randomly across disks, particularly due to zfs's copy-on-write mechanisms. This patch improves performance by splitting scrubs and resilvers into a metadata scanning phase and an IO issuing phase. The metadata scan reads through the structure of the pool and gathers an in-memory queue of I/Os, sorted by size and offset on disk. The issuing phase will then issue the scrub I/Os as sequentially as possible, greatly improving performance. This patch also updates and cleans up some of the scan code which has not been updated in several years. Reviewed-by: Brian Behlendorf <[email protected]> Authored-by: Saso Kiselkov <[email protected]> Authored-by: Alek Pinchuk <[email protected]> Authored-by: Tom Caputi <[email protected]> Signed-off-by: Tom Caputi <[email protected]> Closes #3625 Closes #6256
* Scale the dbuf cache with arc_cchrisrd2017-09-291-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | Commit d3c2ae1 introduced a dbuf cache with a default size of the minimum of 100M or 1/32 maximum ARC size. (These figures may be adjusted using dbuf_cache_max_bytes and dbuf_cache_max_shift.) The dbuf cache is counted as metadata for the purposes of ARC size calculations. On a 1GB box the ARC maximum size defaults to c_max 493M which gives a dbuf cache default minimum size of 15.4M, and the ARC metadata defaults to minimum 16M. I.e. the dbuf cache is an significant proportion of the minimum metadata size. With other overheads involved this actually means the ARC metadata doesn't get down to the minimum. This patch dynamically scales the dbuf cache to the target ARC size instead of statically scaling it to the maximum ARC size. (The scale is still set by dbuf_cache_max_shift and the maximum size is still fixed by dbuf_cache_max_bytes.) Using the target ARC size rather than the current ARC size is done to help the ARC reach the target rather than simply focusing on the current size. Reviewed-by: Chunwei Chen <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: George Melikov <[email protected]> Signed-off-by: Chris Dunlop <[email protected]> Issue #6506 Closes #6561
* Native Encryption for ZFS on LinuxTom Caputi2017-08-141-14/+55
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This change incorporates three major pieces: The first change is a keystore that manages wrapping and encryption keys for encrypted datasets. These commands mostly involve manipulating the new DSL Crypto Key ZAP Objects that live in the MOS. Each encrypted dataset has its own DSL Crypto Key that is protected with a user's key. This level of indirection allows users to change their keys without re-encrypting their entire datasets. The change implements the new subcommands "zfs load-key", "zfs unload-key" and "zfs change-key" which allow the user to manage their encryption keys and settings. In addition, several new flags and properties have been added to allow dataset creation and to make mounting and unmounting more convenient. The second piece of this patch provides the ability to encrypt, decyrpt, and authenticate protected datasets. Each object set maintains a Merkel tree of Message Authentication Codes that protect the lower layers, similarly to how checksums are maintained. This part impacts the zio layer, which handles the actual encryption and generation of MACs, as well as the ARC and DMU, which need to be able to handle encrypted buffers and protected data. The last addition is the ability to do raw, encrypted sends and receives. The idea here is to send raw encrypted and compressed data and receive it exactly as is on a backup system. This means that the dataset on the receiving system is protected using the same user key that is in use on the sending side. By doing so, datasets can be efficiently backed up to an untrusted system without fear of data being compromised. Reviewed by: Matthew Ahrens <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Reviewed-by: Jorgen Lundman <[email protected]> Signed-off-by: Tom Caputi <[email protected]> Closes #494 Closes #5769
* zfs_arc_num_sublists_per_state should be common to all multilistsMatthew Ahrens2017-02-151-2/+0
| | | | | | | | | | | | | The global tunable zfs_arc_num_sublists_per_state is used by the ARC and the dbuf cache, and other users are planned. We should change this tunable to be common to all multilists. This tuning may be overridden on a per-multilist basis. Reviewed-by: Pavel Zakharov <[email protected]> Reviewed-by: Dan Kimmel <[email protected]> Reviewed-by: Tony Hutter <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Matthew Ahrens <[email protected]> Closes #5764
* DLPX-44733 combine arc_buf_alloc_impl() with arc_buf_clone()Dan Kimmel2016-09-131-1/+1
| | | | | | | | Authored by: Dan Kimmel <[email protected]> Reviewed by: Tom Caputi <[email protected]> Reviewed by: Brian Behlendorf <[email protected]> Ported by: David Quigley <[email protected]> Issue #5078
* DLPX-40252 integrate EP-476 compressed zfs send/receiveDan Kimmel2016-09-131-3/+17
| | | | | | | | Authored by: Dan Kimmel <[email protected]> Reviewed by: Tom Caputi <[email protected]> Reviewed by: Brian Behlendorf <[email protected]> Ported by: David Quigley <[email protected]> Issue #5078
* OpenZFS 6950 - ARC should cache compressed dataGeorge Wilson2016-09-131-34/+59
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Authored by: George Wilson <[email protected]> Reviewed by: Prakash Surya <[email protected]> Reviewed by: Dan Kimmel <[email protected]> Reviewed by: Matt Ahrens <[email protected]> Reviewed by: Paul Dagnelie <[email protected]> Reviewed by: Tom Caputi <[email protected]> Reviewed by: Brian Behlendorf <[email protected]> Ported by: David Quigley <[email protected]> This review covers the reading and writing of compressed arc headers, sharing data between the arc_hdr_t and the arc_buf_t, and the implementation of a new dbuf cache to keep frequently access data uncompressed. I've added a new member to l1 arc hdr called b_pdata. The b_pdata always hangs off the arc_buf_hdr_t (if an L1 hdr is in use) and points to the physical block for that DVA. The physical block may or may not be compressed. If compressed arc is enabled and the block on-disk is compressed, then the b_pdata will match the block on-disk and remain compressed in memory. If the block on disk is not compressed, then neither will the b_pdata. Lastly, if compressed arc is disabled, then b_pdata will always be an uncompressed version of the on-disk block. Typically the arc will cache only the arc_buf_hdr_t and will aggressively evict any arc_buf_t's that are no longer referenced. This means that the arc will primarily have compressed blocks as the arc_buf_t's are considered overhead and are always uncompressed. When a consumer reads a block we first look to see if the arc_buf_hdr_t is cached. If the hdr is cached then we allocate a new arc_buf_t and decompress the b_pdata contents into the arc_buf_t's b_data. If the hdr already has a arc_buf_t, then we will allocate an additional arc_buf_t and bcopy the uncompressed contents from the first arc_buf_t to the new one. Writing to the compressed arc requires that we first discard the b_pdata since the physical block is about to be rewritten. The new data contents will be passed in via an arc_buf_t (uncompressed) and during the I/O pipeline stages we will copy the physical block contents to a newly allocated b_pdata. When an l2arc is inuse it will also take advantage of the b_pdata. Now the l2arc will always write the contents of b_pdata to the l2arc. This means that when compressed arc is enabled that the l2arc blocks are identical to those stored in the main data pool. This provides a significant advantage since we can leverage the bp's checksum when reading from the l2arc to determine if the contents are valid. If the compressed arc is disabled, then we must first transform the read block to look like the physical block in the main data pool before comparing the checksum and determining it's valid. OpenZFS-issue: https://www.illumos.org/issues/6950 OpenZFS-commit: https://github.com/openzfs/openzfs/commit/7fc10f0 Issue #5078
* Limit the amount of dnode metadata in the ARCTim Chase2016-07-251-1/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Metadata-intensive workloads can cause the ARC to become permanently filled with dnode_t objects as they're pinned by the VFS layer. Subsequent data-intensive workloads may only benefit from about 25% of the potential ARC (arc_c_max - arc_meta_limit). In order to help track metadata usage more precisely, the other_size metadata arcstat has replaced with dbuf_size, dnode_size and bonus_size. The new zfs_arc_dnode_limit tunable, which defaults to 10% of zfs_arc_meta_limit, defines the minimum number of bytes which is desirable to be consumed by dnodes. Attempts to evict non-metadata will trigger async prune tasks if the space used by dnodes exceeds this limit. The new zfs_arc_dnode_reduce_percent tunable specifies the amount by which the excess dnode space is attempted to be pruned as a percentage of the amount by which zfs_arc_dnode_limit is being exceeded. By default, it tries to unpin 10% of the dnodes. The problem of dnode metadata pinning was observed with the following testing procedure (in this example, zfs_arc_max is set to 4GiB): - Create a large number of small files until arc_meta_used exceeds arc_meta_limit (3GiB with default tuning) and arc_prune starts increasing. - Create a 3GiB file with dd. Observe arc_mata_used. It will still be around 3GiB. - Repeatedly read the 3GiB file and observe arc_meta_limit as before. It will continue to stay around 3GiB. With this modification, space for the 3GiB file is gradually made available as subsequent demands on the ARC are made. The previous behavior can be restored by setting zfs_arc_dnode_limit to the same value as the zfs_arc_meta_limit. Signed-off-by: Tim Chase <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Issue #4345 Issue #4512 Issue #4773 Closes #4858
* OpenZFS 6513 - partially filled holes lose birth timePaul Dagnelie2016-06-211-4/+6
| | | | | | | | | | | | | | | | | | | | Reviewed by: Matthew Ahrens <[email protected]> Reviewed by: George Wilson <[email protected]> Reviewed by: Boris Protopopov <[email protected]> Approved by: Richard Lowe <[email protected]>a Ported by: Boris Protopopov <[email protected]> Signed-off-by: Boris Protopopov <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> OpenZFS-issue: https://www.illumos.org/issues/6513 OpenZFS-commit: https://github.com/openzfs/openzfs/commit/8df0bcf0 If a ZFS object contains a hole at level one, and then a data block is created at level 0 underneath that l1 block, l0 holes will be created. However, these l0 holes do not have the birth time property set; as a result, incremental sends will not send those holes. Fix is to modify the dbuf_read code to fill in birth time data.
* Illumos 5987 - zfs prefetch code needs workMatthew Ahrens2016-01-121-12/+16
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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]>
* Illumos 6214 - zpools going southArne Jansen2015-09-111-14/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | 6214 zpools going south Reviewed by: Igor Kozhukhov <[email protected]> Reviewed by: George Wilson <[email protected]> Reviewed by: Dan McDonald <[email protected]> Reviewed by: Saso Kiselkov <[email protected]> References: https://www.illumos.org/issues/6214 http://cr.illumos.org/~webrev/sensille/6214_zpools_going_south/ Porting Notes: Reintroduce b_compress to the l2arc_buf_hdr_t. In commit b9541d6 the compression flags were moved to the generic b_flags in the arc_buf_hdr_t. This is a problem because l2arc_compress_buf() may manipulate the compression flags and this can only be done safely under the hash lock which is not held. See Illumos 6214 for a detailed analysis of the race. HDR_GET_COMPRESS() macro was removed from arc_buf_info(). Ported-by: Brian Behlendorf <[email protected]> Closes #3757
* Dbuf hash table should be sized as is the arc hash tableTim Chase2015-09-021-0/+3
| | | | | | | | | | | Commit 49ddb315066e372f31bda29a5c546a9eccc8b418 added the zfs_arc_average_blocksize parameter to allow control over the size of the arc hash table. The dbuf hash table's size should be determined similarly. Signed-off-by: Tim Chase <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #3721
* Make arc_prune() asynchronousBrian Behlendorf2015-06-111-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | As described in the comment above arc_adapt_thread() it is critical that the arc_adapt_thread() function never sleep while holding a hash lock. This behavior was possible in the Linux implementation because the arc_prune() logic was implemented to be synchronous. Under illumos the analogous dnlc_reduce_cache() function is asynchronous. To address this the arc_do_user_prune() function is has been reworked in to two new functions as follows: * arc_prune_async() is an asynchronous implementation which dispatches the prune callback to be run by the system taskq. This makes it suitable to use in the context of the arc_adapt_thread(). * arc_prune() is a synchronous implementation which depends on the arc_prune_async() implementation but blocks until the outstanding callbacks complete. This is used in arc_kmem_reap_now() where it is safe, and expected, that memory will be freed. This patch additionally adds the zfs_arc_meta_strategy module option while allows the meta reclaim strategy to be configured. It defaults to a balanced strategy which has been proved to work well under Linux but the illumos meta-only strategy can be enabled. Signed-off-by: Tim Chase <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]>
* Illumos 5497 - lock contention on arcs_mtxPrakash Surya2015-06-111-2/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Reviewed by: George Wilson <[email protected]> Reviewed by: Matthew Ahrens <[email protected]> Reviewed by: Richard Elling <[email protected]> Approved by: Dan McDonald <[email protected]> Porting notes and other significant code changes: The illumos 5368 patch (ARC should cache more metadata), which was never picked up by ZoL, is mostly reverted by this patch. Since ZoL relies on the kernel asynchronously calling the shrinker to actually reap memory, the shrinker wakes up arc_reclaim_waiters_cv every time it runs. The arc_adapt_thread() function no longer calls arc_do_user_evicts() since the newly-added arc_user_evicts_thread() calls it periodically. Notable conflicting ZoL commits which conflicted with this patch or whose effects are either duplicated or un-done by this patch: 302f753 - Integrate ARC more tightly with Linux 39e055c - Adjust arc_p based on "bytes" in arc_shrink f521ce1 - Allow "arc_p" to drop to zero or grow to "arc_c" 77765b5 - Remove "arc_meta_used" from arc_adjust calculation 94520ca - Prune metadata from ghost lists in arc_adjust_meta Trace support for multilist_insert() and multilist_remove() has been added and produces the following output: fio-12498 [077] .... 112936.448324: zfs_multilist__insert: ml { offset 240 numsublists 80 sublistidx 63 } fio-12498 [077] .... 112936.448347: zfs_multilist__remove: ml { offset 240 numsublists 80 sublistidx 29 } The following arcstats have been removed: recycle_miss - Used by arcstat.py and arc_summary.py, both of which have been updated appropriately. l2_writes_hdr_miss The following arcstats have been added: evict_not_enough - Number of times arc_evict_state() was unable to evict enough buffers to reach its target amount. evict_l2_skip - Number of times arc_evict_hdr() skipped eviction because it was being written to the l2arc. l2_writes_lock_retry - Replaces l2_writes_hdr_miss. Number of times l2arc_write_done() failed to acquire hash_lock (and re-tries). arc_meta_min - Shows the value of the zfs_arc_meta_min module parameter (see below). The "index" column of the "dbuf" kstat has been removed since it doesn't have a direct analog in the new multilist scheme. Additional multilist- related stats could be added in the future but would likely require extensions to the mulilist API. The following module parameters have been added: zfs_arc_evict_batch_limit - Number of ARC headers to free per sub-list before moving on to the next sub-list. zfs_arc_meta_min - Enforce a floor on the amount of metadata in the ARC. zfs_arc_num_sublists_per_state - Number of multilist sub-lists per ARC state. zfs_arc_overflow_shift - Controls amount by which the ARC must exceed the target size to be considered "overflowing". Ported-by: Tim Chase <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]
* Illumos 5408 - managing ZFS cache devices requires lots of RAMChris Williamson2015-06-111-4/+23
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 5408 managing ZFS cache devices requires lots of RAM Reviewed by: Christopher Siden <[email protected]> Reviewed by: George Wilson <[email protected]> Reviewed by: Matthew Ahrens <[email protected]> Reviewed by: Don Brady <[email protected]> Reviewed by: Josef 'Jeff' Sipek <[email protected]> Approved by: Garrett D'Amore <[email protected]> Porting notes: Due to the restructuring of the ARC-related structures, this patch conflicts with at least the following existing ZoL commits: 6e1d7276c94cbd7c2e19f9232f6ba4bafa62dbe0 Fix inaccurate arcstat_l2_hdr_size calculations The ARC_SPACE_HDRS constant no longer exists and has been somewhat equivalently replaced by HDR_L2ONLY_SIZE. e0b0ca983d6897bcddf05af2c0e5d01ff66f90db Add visibility in to cached dbufs The new layering of l{1,2}arc_buf_hdr_t within the arc_buf_hdr struct requires additional structure member names to be used when referencing the inner items. Also, the presence of L1 or L2 inner member is indicated by flags using the new HDR_HAS_L{1,2}HDR macros. Ported by: Tim Chase <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]>
* Illumos 5369 - arc flags should be an enumGeorge Wilson2015-06-111-10/+31
| | | | | | | | | | | | | | | | | 5369 arc flags should be an enum 5370 consistent arc_buf_hdr_t naming scheme Reviewed by: Matthew Ahrens <[email protected]> Reviewed by: Alex Reece <[email protected]> Reviewed by: Sebastien Roy <[email protected]> Reviewed by: Richard Elling <[email protected]> Approved by: Richard Lowe <[email protected]> Porting notes: ZoL has moved some ARC definitions into arc_impl.h. Signed-off-by: Brian Behlendorf <[email protected]> Ported by: Tim Chase <[email protected]>
* Handle block pointers with a corrupt logical sizeBrian Behlendorf2014-10-231-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | The general strategy used by ZFS to verify that blocks are valid is to checksum everything. This has the advantage of being extremely robust and generically applicable regardless of the contents of the block. If a blocks checksum is valid then its contents are trusted by the higher layers. This system works exceptionally well as long as bad data is never written with a valid checksum. If this does somehow occur due to a software bug or a memory bit-flip on a non-ECC system it may result in kernel panic. One such place where this could occur is if somehow the logical size stored in a block pointer exceeds the maximum block size. This will result in an attempt to allocate a buffer greater than the maximum block size causing a system panic. To prevent this from happening the arc_read() function has been updated to detect this specific case. If a block pointer with an invalid logical size is passed it will treat the block as if it contained a checksum error. Signed-off-by: Tim Chase <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #2678
* Illumos 4631 - zvol_get_stats triggering too many readsMatthew Ahrens2014-08-201-2/+1
| | | | | | | | | | | | | | | | | | 4631 zvol_get_stats triggering too many reads Reviewed by: Adam Leventhal <[email protected]> Reviewed by: Sebastien Roy <[email protected]> Reviewed by: Matt Ahrens <[email protected]> Approved by: Dan McDonald <[email protected]> References: https://www.illumos.org/issues/4631 https://github.com/illumos/illumos-gate/commit/bbfa8ea Ported-by: Boris Protopopov <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #2612 Closes #2480
* Illumos 4914 - zfs on-disk bookmark structure should be named *_phys_tMatthew Ahrens2014-08-061-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | 4914 zfs on-disk bookmark structure should be named *_phys_t Reviewed by: George Wilson <[email protected]> Reviewed by: Christopher Siden <[email protected]> Reviewed by: Richard Lowe <[email protected]> Reviewed by: Saso Kiselkov <[email protected]> Approved by: Robert Mustacchi <[email protected]> References: https://www.illumos.org/issues/4914 https://github.com/illumos/illumos-gate/commit/7802d7b Porting notes: There were a number of zfsonlinux-specific uses of zbookmark_t which needed to be updated. This should reduce the likelihood of further problems like issue #2094 from occurring. Ported by: Tim Chase <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #2558
* Split "data_size" into "meta" and "data"Prakash Surya2014-02-211-0/+1
| | | | | | | | | | | | | | | | | Previously, the "data_size" field in the arcstats kstat contained the amount of cached "metadata" and "data" in the ARC. The problem is this then made it difficult to extract out just the "metadata" size, or just the "data" size. To make it easier to distinguish the two values, "data_size" has been modified to count only buffers of type ARC_BUFC_DATA, and "meta_size" was added to count only buffers of type ARC_BUFC_METADATA. If one wants the old "data_size" value, simply sum the new "data_size" and "meta_size" values. Signed-off-by: Prakash Surya <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Issue #2110
* Prune metadata from ghost lists in arc_adjust_metaPrakash Surya2014-02-211-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | To maintain a strict limit on the metadata contained in the arc, while preventing the arc buffer headers from completely consuming the "arc_meta_used" space, we need to evict metadata buffers from the arc's ghost lists along with the regular lists. This change modifies arc_adjust_meta such that it more closely models the adjustments made in arc_adjust. "arc_meta_used" is used similarly to "arc_size", and "arc_meta_limit" is used similarly to "arc_c". Testing metadata intensive workloads (e.g. creating, copying, and removing millions of small files and/or directories) has shown this change to make a dramatic improvement to the hit rate maintained in the arc. While I think there is still room for improvement, this is a big step in the right direction. In addition, zpl_free_cached_objects was made into a no-op as I'm not yet sure how to properly implement that function. Signed-off-by: Prakash Surya <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Issue #2110
* Illumos #4045 write throttle & i/o scheduler performance workMatthew Ahrens2013-12-061-8/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 4045 zfs write throttle & i/o scheduler performance work 1. The ZFS i/o scheduler (vdev_queue.c) now divides i/os into 5 classes: sync read, sync write, async read, async write, and scrub/resilver. The scheduler issues a number of concurrent i/os from each class to the device. Once a class has been selected, an i/o is selected from this class using either an elevator algorithem (async, scrub classes) or FIFO (sync classes). The number of concurrent async write i/os is tuned dynamically based on i/o load, to achieve good sync i/o latency when there is not a high load of writes, and good write throughput when there is. See the block comment in vdev_queue.c (reproduced below) for more details. 2. The write throttle (dsl_pool_tempreserve_space() and txg_constrain_throughput()) is rewritten to produce much more consistent delays when under constant load. The new write throttle is based on the amount of dirty data, rather than guesses about future performance of the system. When there is a lot of dirty data, each transaction (e.g. write() syscall) will be delayed by the same small amount. This eliminates the "brick wall of wait" that the old write throttle could hit, causing all transactions to wait several seconds until the next txg opens. One of the keys to the new write throttle is decrementing the amount of dirty data as i/o completes, rather than at the end of spa_sync(). Note that the write throttle is only applied once the i/o scheduler is issuing the maximum number of outstanding async writes. See the block comments in dsl_pool.c and above dmu_tx_delay() (reproduced below) for more details. This diff has several other effects, including: * the commonly-tuned global variable zfs_vdev_max_pending has been removed; use per-class zfs_vdev_*_max_active values or zfs_vdev_max_active instead. * the size of each txg (meaning the amount of dirty data written, and thus the time it takes to write out) is now controlled differently. There is no longer an explicit time goal; the primary determinant is amount of dirty data. Systems that are under light or medium load will now often see that a txg is always syncing, but the impact to performance (e.g. read latency) is minimal. Tune zfs_dirty_data_max and zfs_dirty_data_sync to control this. * zio_taskq_batch_pct = 75 -- Only use 75% of all CPUs for compression, checksum, etc. This improves latency by not allowing these CPU-intensive tasks to consume all CPU (on machines with at least 4 CPU's; the percentage is rounded up). --matt APPENDIX: problems with the current i/o scheduler The current ZFS i/o scheduler (vdev_queue.c) is deadline based. The problem with this is that if there are always i/os pending, then certain classes of i/os can see very long delays. For example, if there are always synchronous reads outstanding, then no async writes will be serviced until they become "past due". One symptom of this situation is that each pass of the txg sync takes at least several seconds (typically 3 seconds). If many i/os become "past due" (their deadline is in the past), then we must service all of these overdue i/os before any new i/os. This happens when we enqueue a batch of async writes for the txg sync, with deadlines 2.5 seconds in the future. If we can't complete all the i/os in 2.5 seconds (e.g. because there were always reads pending), then these i/os will become past due. Now we must service all the "async" writes (which could be hundreds of megabytes) before we service any reads, introducing considerable latency to synchronous i/os (reads or ZIL writes). Notes on porting to ZFS on Linux: - zio_t gained new members io_physdone and io_phys_children. Because object caches in the Linux port call the constructor only once at allocation time, objects may contain residual data when retrieved from the cache. Therefore zio_create() was updated to zero out the two new fields. - vdev_mirror_pending() relied on the depth of the per-vdev pending queue (vq->vq_pending_tree) to select the least-busy leaf vdev to read from. This tree has been replaced by vq->vq_active_tree which is now used for the same purpose. - vdev_queue_init() used the value of zfs_vdev_max_pending to determine the number of vdev I/O buffers to pre-allocate. That global no longer exists, so we instead use the sum of the *_max_active values for each of the five I/O classes described above. - The Illumos implementation of dmu_tx_delay() delays a transaction by sleeping in condition variable embedded in the thread (curthread->t_delay_cv). We do not have an equivalent CV to use in Linux, so this change replaced the delay logic with a wrapper called zfs_sleep_until(). This wrapper could be adopted upstream and in other downstream ports to abstract away operating system-specific delay logic. - These tunables are added as module parameters, and descriptions added to the zfs-module-parameters.5 man page. spa_asize_inflation zfs_deadman_synctime_ms zfs_vdev_max_active zfs_vdev_async_write_active_min_dirty_percent zfs_vdev_async_write_active_max_dirty_percent zfs_vdev_async_read_max_active zfs_vdev_async_read_min_active zfs_vdev_async_write_max_active zfs_vdev_async_write_min_active zfs_vdev_scrub_max_active zfs_vdev_scrub_min_active zfs_vdev_sync_read_max_active zfs_vdev_sync_read_min_active zfs_vdev_sync_write_max_active zfs_vdev_sync_write_min_active zfs_dirty_data_max_percent zfs_delay_min_dirty_percent zfs_dirty_data_max_max_percent zfs_dirty_data_max zfs_dirty_data_max_max zfs_dirty_data_sync zfs_delay_scale The latter four have type unsigned long, whereas they are uint64_t in Illumos. This accommodates Linux's module_param() supported types, but means they may overflow on 32-bit architectures. The values zfs_dirty_data_max and zfs_dirty_data_max_max are the most likely to overflow on 32-bit systems, since they express physical RAM sizes in bytes. In fact, Illumos initializes zfs_dirty_data_max_max to 2^32 which does overflow. To resolve that, this port instead initializes it in arc_init() to 25% of physical RAM, and adds the tunable zfs_dirty_data_max_max_percent to override that percentage. While this solution doesn't completely avoid the overflow issue, it should be a reasonable default for most systems, and the minority of affected systems can work around the issue by overriding the defaults. - Fixed reversed logic in comment above zfs_delay_scale declaration. - Clarified comments in vdev_queue.c regarding when per-queue minimums take effect. - Replaced dmu_tx_write_limit in the dmu_tx kstat file with dmu_tx_dirty_delay and dmu_tx_dirty_over_max. The first counts how many times a transaction has been delayed because the pool dirty data has exceeded zfs_delay_min_dirty_percent. The latter counts how many times the pool dirty data has exceeded zfs_dirty_data_max (which we expect to never happen). - The original patch would have regressed the bug fixed in zfsonlinux/zfs@c418410, which prevented users from setting the zfs_vdev_aggregation_limit tuning larger than SPA_MAXBLOCKSIZE. A similar fix is added to vdev_queue_aggregate(). - In vdev_queue_io_to_issue(), dynamically allocate 'zio_t search' on the heap instead of the stack. In Linux we can't afford such large structures on the stack. Reviewed by: George Wilson <[email protected]> Reviewed by: Adam Leventhal <[email protected]> Reviewed by: Christopher Siden <[email protected]> Reviewed by: Ned Bass <[email protected]> Reviewed by: Brendan Gregg <[email protected]> Approved by: Robert Mustacchi <[email protected]> References: http://www.illumos.org/issues/4045 illumos/illumos-gate@69962b5647e4a8b9b14998733b765925381b727e Ported-by: Ned Bass <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #1913
* Illumos #3112, #3113, #3114Matthew Ahrens2013-11-051-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | 3112 ztest does not honor ZFS_DEBUG 3113 ztest should use watchpoints to protect frozen arc bufs 3114 some leaked nvlists in zfsdev_ioctl Reviewed by: Adam Leventhal <[email protected]> Reviewed by: Matt Amdur <[email protected]> Reviewed by: George Wilson <[email protected]> Reviewed by: Christopher Siden <[email protected]> Approved by: Eric Schrock <[email protected]> References: https://www.illumos.org/issues/3112 https://www.illumos.org/issues/3113 https://www.illumos.org/issues/3114 illumos/illumos-gate@cd1c8b85eb30b568e9816221430c479ace7a559d The /proc/self/cmd watchpoint interface is specific to Solaris. Therefore, the #3113 implementation was reworked to use the more portable mprotect(2) system call. When the pages are watched they are marked read-only for protection. Any write to the protected address range immediately trigger a SIGSEGV. The pages are marked writable again when they are unwatched. Ported-by: Brian Behlendorf <[email protected]> Issue #1489
* Add visibility in to cached dbufsBrian Behlendorf2013-10-251-0/+31
| | | | | | | | | | | | | | | | | | | | | | | | Currently there is no mechanism to inspect which dbufs are being cached by the system. There are some coarse counters in arcstats by they only give a rough idea of what's being cached. This patch aims to improve the current situation by adding a new dbufs kstat. When read this new kstat will walk all cached dbufs linked in to the dbuf_hash. For each dbuf it will dump detailed information about the buffer. It will also dump additional information about the referenced arc buffer and its related dnode. This provides a more complete view in to exactly what is being cached. With this generic infrastructure in place utilities can be written to post-process the data to understand exactly how the caching is working. For example, the data could be processed to show a list of all cached dnodes and how much space they're consuming. Or a similar list could be generated based on dnode type. Many other ways to interpret the data exist based on what kinds of questions you're trying to answer. Signed-off-by: Brian Behlendorf <[email protected]> Signed-off-by: Prakash Surya <[email protected]>
* Illumos #3464Matthew Ahrens2013-09-041-1/+1
| | | | | | | | | | | | | | | | | 3464 zfs synctask code needs restructuring Reviewed by: Dan Kimmel <[email protected]> Reviewed by: Adam Leventhal <[email protected]> Reviewed by: George Wilson <[email protected]> Reviewed by: Christopher Siden <[email protected]> Approved by: Garrett D'Amore <[email protected]> References: https://www.illumos.org/issues/3464 illumos/illumos-gate@3b2aab18808792cbd248a12f1edf139b89833c13 Ported-by: Tim Chase <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #1495
* Illumos #3137 L2ARC compressionSaso Kiselkov2013-08-081-3/+5
| | | | | | | | | | | | | | | | | | | | | | | 3137 L2ARC compression Reviewed by: George Wilson <[email protected]> Reviewed by: Matthew Ahrens <[email protected]> Approved by: Dan McDonald <[email protected]> References: illumos/illumos-gate@aad02571bc59671aa3103bb070ae365f531b0b62 https://www.illumos.org/issues/3137 http://wiki.illumos.org/display/illumos/L2ARC+Compression Notes for Linux port: A l2arc_nocompress module option was added to prevent the compression of l2arc buffers regardless of how a dataset's compression property is set. This allows the legacy behavior to be preserved. Ported by: James H <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #1379
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