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* Extend zdb to print inconsistencies in livelists and metaslabsMatthew Ahrens2020-07-141-0/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Livelists and spacemaps are data structures that are logs of allocations and frees. Livelists entries are block pointers (blkptr_t). Spacemaps entries are ranges of numbers, most often used as to track allocated/freed regions of metaslabs/vdevs. These data structures can become self-inconsistent, for example if a block or range can be "double allocated" (two allocation records without an intervening free) or "double freed" (two free records without an intervening allocation). ZDB (as well as zfs running in the kernel) can detect these inconsistencies when loading livelists and metaslab. However, it generally halts processing when the error is detected. When analyzing an on-disk problem, we often want to know the entire set of inconsistencies, which is not possible with the current behavior. This commit adds a new flag, `zdb -y`, which analyzes the livelist and metaslab data structures and displays all of their inconsistencies. Note that this is different from the leak detection performed by `zdb -b`, which checks for inconsistencies between the spacemaps and the tree of block pointers, but assumes the spacemaps are self-consistent. The specific checks added are: Verify livelists by iterating through each sublivelists and: - report leftover FREEs - report double ALLOCs and double FREEs - record leftover ALLOCs together with their TXG [see Cross Check] Verify spacemaps by iterating over each metaslab and: - iterate over spacemap and then the metaslab's entries in the spacemap log, then report any double FREEs and double ALLOCs Verify that livelists are consistenet with spacemaps. The space referenced by livelists (after using the FREE's to cancel out corresponding ALLOCs) should be allocated, according to the spacemaps. Reviewed-by: Serapheim Dimitropoulos <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Co-authored-by: Sara Hartse <[email protected]> Signed-off-by: Matthew Ahrens <[email protected]> External-issue: DLPX-66031 Closes #10515
* Log Spacemap ProjectSerapheim Dimitropoulos2019-07-161-1/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | = Motivation At Delphix we've seen a lot of customer systems where fragmentation is over 75% and random writes take a performance hit because a lot of time is spend on I/Os that update on-disk space accounting metadata. Specifically, we seen cases where 20% to 40% of sync time is spend after sync pass 1 and ~30% of the I/Os on the system is spent updating spacemaps. The problem is that these pools have existed long enough that we've touched almost every metaslab at least once, and random writes scatter frees across all metaslabs every TXG, thus appending to their spacemaps and resulting in many I/Os. To give an example, assuming that every VDEV has 200 metaslabs and our writes fit within a single spacemap block (generally 4K) we have 200 I/Os. Then if we assume 2 levels of indirection, we need 400 additional I/Os and since we are talking about metadata for which we keep 2 extra copies for redundancy we need to triple that number, leading to a total of 1800 I/Os per VDEV every TXG. We could try and decrease the number of metaslabs so we have less I/Os per TXG but then each metaslab would cover a wider range on disk and thus would take more time to be loaded in memory from disk. In addition, after it's loaded, it's range tree would consume more memory. Another idea would be to just increase the spacemap block size which would allow us to fit more entries within an I/O block resulting in fewer I/Os per metaslab and a speedup in loading time. The problem is still that we don't deal with the number of I/Os going up as the number of metaslabs is increasing and the fact is that we generally write a lot to a few metaslabs and a little to the rest of them. Thus, just increasing the block size would actually waste bandwidth because we won't be utilizing our bigger block size. = About this patch This patch introduces the Log Spacemap project which provides the solution to the above problem while taking into account all the aforementioned tradeoffs. The details on how it achieves that can be found in the references sections below and in the code (see Big Theory Statement in spa_log_spacemap.c). Even though the change is fairly constraint within the metaslab and lower-level SPA codepaths, there is a side-change that is user-facing. The change is that VDEV IDs from VDEV holes will no longer be reused. To give some background and reasoning for this, when a log device is removed and its VDEV structure was replaced with a hole (or was compacted; if at the end of the vdev array), its vdev_id could be reused by devices added after that. Now with the pool-wide space maps recording the vdev ID, this behavior can cause problems (e.g. is this entry referring to a segment in the new vdev or the removed log?). Thus, to simplify things the ID reuse behavior is gone and now vdev IDs for top-level vdevs are truly unique within a pool. = Testing The illumos implementation of this feature has been used internally for a year and has been in production for ~6 months. For this patch specifically there don't seem to be any regressions introduced to ZTS and I have been running zloop for a week without any related problems. = Performance Analysis (Linux Specific) All performance results and analysis for illumos can be found in the links of the references. Redoing the same experiments in Linux gave similar results. Below are the specifics of the Linux run. After the pool reached stable state the percentage of the time spent in pass 1 per TXG was 64% on average for the stock bits while the log spacemap bits stayed at 95% during the experiment (graph: sdimitro.github.io/img/linux-lsm/PercOfSyncInPassOne.png). Sync times per TXG were 37.6 seconds on average for the stock bits and 22.7 seconds for the log spacemap bits (related graph: sdimitro.github.io/img/linux-lsm/SyncTimePerTXG.png). As a result the log spacemap bits were able to push more TXGs, which is also the reason why all graphs quantified per TXG have more entries for the log spacemap bits. Another interesting aspect in terms of txg syncs is that the stock bits had 22% of their TXGs reach sync pass 7, 55% reach sync pass 8, and 20% reach 9. The log space map bits reached sync pass 4 in 79% of their TXGs, sync pass 7 in 19%, and sync pass 8 at 1%. This emphasizes the fact that not only we spend less time on metadata but we also iterate less times to convergence in spa_sync() dirtying objects. [related graphs: stock- sdimitro.github.io/img/linux-lsm/NumberOfPassesPerTXGStock.png lsm- sdimitro.github.io/img/linux-lsm/NumberOfPassesPerTXGLSM.png] Finally, the improvement in IOPs that the userland gains from the change is approximately 40%. There is a consistent win in IOPS as you can see from the graphs below but the absolute amount of improvement that the log spacemap gives varies within each minute interval. sdimitro.github.io/img/linux-lsm/StockVsLog3Days.png sdimitro.github.io/img/linux-lsm/StockVsLog10Hours.png = Porting to Other Platforms For people that want to port this commit to other platforms below is a list of ZoL commits that this patch depends on: Make zdb results for checkpoint tests consistent db587941c5ff6dea01932bb78f70db63cf7f38ba Update vdev_is_spacemap_addressable() for new spacemap encoding 419ba5914552c6185afbe1dd17b3ed4b0d526547 Simplify spa_sync by breaking it up to smaller functions 8dc2197b7b1e4d7ebc1420ea30e51c6541f1d834 Factor metaslab_load_wait() in metaslab_load() b194fab0fb6caad18711abccaff3c69ad8b3f6d3 Rename range_tree_verify to range_tree_verify_not_present df72b8bebe0ebac0b20e0750984bad182cb6564a Change target size of metaslabs from 256GB to 16GB c853f382db731e15a87512f4ef1101d14d778a55 zdb -L should skip leak detection altogether 21e7cf5da89f55ce98ec1115726b150e19eefe89 vs_alloc can underflow in L2ARC vdevs 7558997d2f808368867ca7e5234e5793446e8f3f Simplify log vdev removal code 6c926f426a26ffb6d7d8e563e33fc176164175cb Get rid of space_map_update() for ms_synced_length 425d3237ee88abc53d8522a7139c926d278b4b7f Introduce auxiliary metaslab histograms 928e8ad47d3478a3d5d01f0dd6ae74a9371af65e Error path in metaslab_load_impl() forgets to drop ms_sync_lock 8eef997679ba54547f7d361553d21b3291f41ae7 = References Background, Motivation, and Internals of the Feature - OpenZFS 2017 Presentation: youtu.be/jj2IxRkl5bQ - Slides: slideshare.net/SerapheimNikolaosDim/zfs-log-spacemaps-project Flushing Algorithm Internals & Performance Results (Illumos Specific) - Blogpost: sdimitro.github.io/post/zfs-lsm-flushing/ - OpenZFS 2018 Presentation: youtu.be/x6D2dHRjkxw - Slides: slideshare.net/SerapheimNikolaosDim/zfs-log-spacemap-flushing-algorithm Upstream Delphix Issues: DLPX-51539, DLPX-59659, DLPX-57783, DLPX-61438, DLPX-41227, DLPX-59320 DLPX-63385 Reviewed-by: Sean Eric Fagan <[email protected]> Reviewed-by: Matt Ahrens <[email protected]> Reviewed-by: George Wilson <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Serapheim Dimitropoulos <[email protected]> Closes #8442
* Introduce auxiliary metaslab histogramsSerapheim Dimitropoulos2019-02-201-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch introduces 3 new histograms per metaslab. These histograms track segments that have made it to the metaslab's space map histogram (and are part of the spacemap) but have not yet reached the ms_allocatable tree on loaded metaslab's because these metaslab's are currently syncing and haven't gone through metaslab_sync_done() yet. The histograms help when we decide whether to load an unloaded metaslab in-order to allocate from it. When calculating the weight of an unloaded metaslab traditionally, we look at the highest bucket of its spacemap's histogram. The problem is that we are not guaranteed to be able to allocated that segment when we load the metaslab because it may still be at the freeing, freed, or defer trees. The new histograms are used when we try to calculate an unloaded metaslab's weight to deal with this issue by removing segments that have would not be in the allocatable tree at runtime. Note, that this method of dealing with this is not completely accurate as adjacent segments are not always consolidated in the space map histogram of a metaslab. In addition and to make things deterministic, we always reset the weight of unloaded metaslabs based on their space map weight (instead of doing that on a need basis). Thus, every time a metaslab is loaded and its weight is reset again (from the weight based on its space map to the one based on its allocatable range tree) we expect (and assert) that this change in weight can only get better if it doesn't stay the same. Reviewed by: Paul Dagnelie <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Reviewed by: Matt Ahrens <[email protected]> Signed-off-by: Serapheim Dimitropoulos <[email protected]> Closes #8358
* Get rid of space_map_update() for ms_synced_lengthSerapheim Dimitropoulos2019-02-121-13/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Initially, metaslabs and space maps used to be the same thing in ZFS. Later, we started differentiating them by referring to the space map as the on-disk state of the metaslab, making the metaslab a higher-level concept that is metadata that deals with space accounting. Today we've managed to split that code furthermore, with the space map being its own on-disk data structure used in areas of ZFS besides metaslabs (e.g. the vdev-wide space maps used for zpool checkpoint or vdev removal features). This patch refactors the space map code to further split the space map code from the metaslab code. It does so by getting rid of the idea that the space map can have a different in-core and on-disk length (sm_length vs smp_length) which is something that is only used for the metaslab code, and other consumers of space maps just have to deal with. Instead, this patch introduces changes that move the old in-core length of the metaslab's space map to the metaslab structure itself (see ms_synced_length field) while making the space map code only care about the actual space map's length on-disk. The result of this is that space map consumers no longer have to deal with syncing two different lengths for the same structure (e.g. space_map_update() goes away) while metaslab specific behavior stays within the metaslab code. Specifically, the ms_synced_length field keeps track of the amount of data metaslab_load() can read from the metaslab's space map while working concurrently with metaslab_sync() that may be appending to that same space map. As a side note, the patch also adds a few comments around the metaslab code documenting some assumptions and expected behavior. Reviewed-by: Matt Ahrens <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Reviewed by: Pavel Zakharov <[email protected]> Signed-off-by: Serapheim Dimitropoulos <[email protected]> Closes #8328
* OpenZFS 9238 - ZFS Spacemap Encoding V2Serapheim Dimitropoulos2018-07-051-31/+83
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Motivation ========== The current space map encoding has the following disadvantages: [1] Assuming 512 sector size each entry can represent at most 16MB for a segment. This makes the encoding very inefficient for large regions of space. [2] As vdev-wide space maps have started to be used by new features (i.e. device removal, zpool checkpoint) we've started imposing limits in the vdevs that can be used with them based on the maximum addressable offset (currently 64PB for a top-level vdev). New encoding ============ The layout can be found at space_map.h and it remains backwards compatible with the old one. The introduced two-word entry format, besides extending the limits imposed by the single-entry layout, also includes a vdev field and some extra padding after its prefix. The extra padding after the prefix should is reserved for future usage (e.g. new prefixes for future encodings or new fields for flags). The new vdev field not only makes the space maps more self-descriptive, but also opens the doors for pool-wide space maps (expected to be used in the log spacemap project). One final important note is that the number of bits used for vdevs is reduced to 24 bits for blkptrs. That was decided as we don't know of any setups that use more than 16M vdevs for the time being and we wanted to fit the vdev field in the space map. In addition that gives us some extra bits in dva_t. Other references: ================= The new encoding is also discussed towards the end of the Log Space Map presentation from 2017's OpenZFS summit. Link: https://www.youtube.com/watch?v=jj2IxRkl5bQ Authored by: Serapheim Dimitropoulos <[email protected]> Reviewed by: Matt Ahrens <[email protected]> Reviewed by: George Wilson <[email protected]> Reviewed by: Brian Behlendorf <[email protected]> Approved by: Gordon Ross <[email protected]> Ported-by: Tim Chase <[email protected]> Signed-off-by: Tim Chase <[email protected]> OpenZFS-commit: https://github.com/openzfs/openzfs/commit/90a56e6d OpenZFS-issue: https://www.illumos.org/issues/9238 Closes #7665
* OpenZFS 9166 - zfs storage pool checkpointSerapheim Dimitropoulos2018-06-261-5/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Details about the motivation of this feature and its usage can be found in this blogpost: https://sdimitro.github.io/post/zpool-checkpoint/ A lightning talk of this feature can be found here: https://www.youtube.com/watch?v=fPQA8K40jAM Implementation details can be found in big block comment of spa_checkpoint.c Side-changes that are relevant to this commit but not explained elsewhere: * renames members of "struct metaslab trees to be shorter without losing meaning * space_map_{alloc,truncate}() accept a block size as a parameter. The reason is that in the current state all space maps that we allocate through the DMU use a global tunable (space_map_blksz) which defauls to 4KB. This is ok for metaslab space maps in terms of bandwirdth since they are scattered all over the disk. But for other space maps this default is probably not what we want. Examples are device removal's vdev_obsolete_sm or vdev_chedkpoint_sm from this review. Both of these have a 1:1 relationship with each vdev and could benefit from a bigger block size. Porting notes: * The part of dsl_scan_sync() which handles async destroys has been moved into the new dsl_process_async_destroys() function. * Remove "VERIFY(!(flags & FWRITE))" in "kernel.c" so zhack can write to block device backed pools. * ZTS: * Fix get_txg() in zpool_sync_001_pos due to "checkpoint_txg". * Don't use large dd block sizes on /dev/urandom under Linux in checkpoint_capacity. * Adopt Delphix-OS's setting of 4 (spa_asize_inflation = SPA_DVAS_PER_BP + 1) for the checkpoint_capacity test to speed its attempts to fill the pool * Create the base and nested pools with sync=disabled to speed up the "setup" phase. * Clear labels in test pool between checkpoint tests to avoid duplicate pool issues. * The import_rewind_device_replaced test has been marked as "known to fail" for the reasons listed in its DISCLAIMER. * New module parameters: zfs_spa_discard_memory_limit, zfs_remove_max_bytes_pause (not documented - debugging only) vdev_max_ms_count (formerly metaslabs_per_vdev) vdev_min_ms_count Authored by: Serapheim Dimitropoulos <[email protected]> Reviewed by: Matthew Ahrens <[email protected]> Reviewed by: John Kennedy <[email protected]> Reviewed by: Dan Kimmel <[email protected]> Reviewed by: Brian Behlendorf <[email protected]> Approved by: Richard Lowe <[email protected]> Ported-by: Tim Chase <[email protected]> Signed-off-by: Tim Chase <[email protected]> OpenZFS-issue: https://illumos.org/issues/9166 OpenZFS-commit: https://github.com/openzfs/openzfs/commit/7159fdb8 Closes #7570
* OpenZFS 7614, 9064 - zfs device evacuation/removalMatthew Ahrens2018-04-141-3/+10
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | OpenZFS 7614 - zfs device evacuation/removal OpenZFS 9064 - remove_mirror should wait for device removal to complete This project allows top-level vdevs to be removed from the storage pool with "zpool remove", reducing the total amount of storage in the pool. This operation copies all allocated regions of the device to be removed onto other devices, recording the mapping from old to new location. After the removal is complete, read and free operations to the removed (now "indirect") vdev must be remapped and performed at the new location on disk. The indirect mapping table is kept in memory whenever the pool is loaded, so there is minimal performance overhead when doing operations on the indirect vdev. The size of the in-memory mapping table will be reduced when its entries become "obsolete" because they are no longer used by any block pointers in the pool. An entry becomes obsolete when all the blocks that use it are freed. An entry can also become obsolete when all the snapshots that reference it are deleted, and the block pointers that reference it have been "remapped" in all filesystems/zvols (and clones). Whenever an indirect block is written, all the block pointers in it will be "remapped" to their new (concrete) locations if possible. This process can be accelerated by using the "zfs remap" command to proactively rewrite all indirect blocks that reference indirect (removed) vdevs. Note that when a device is removed, we do not verify the checksum of the data that is copied. This makes the process much faster, but if it were used on redundant vdevs (i.e. mirror or raidz vdevs), it would be possible to copy the wrong data, when we have the correct data on e.g. the other side of the mirror. At the moment, only mirrors and simple top-level vdevs can be removed and no removal is allowed if any of the top-level vdevs are raidz. Porting Notes: * Avoid zero-sized kmem_alloc() in vdev_compact_children(). The device evacuation code adds a dependency that vdev_compact_children() be able to properly empty the vdev_child array by setting it to NULL and zeroing vdev_children. Under Linux, kmem_alloc() and related functions return a sentinel pointer rather than NULL for zero-sized allocations. * Remove comment regarding "mpt" driver where zfs_remove_max_segment is initialized to SPA_MAXBLOCKSIZE. Change zfs_condense_indirect_commit_entry_delay_ticks to zfs_condense_indirect_commit_entry_delay_ms for consistency with most other tunables in which delays are specified in ms. * ZTS changes: Use set_tunable rather than mdb Use zpool sync as appropriate Use sync_pool instead of sync Kill jobs during test_removal_with_operation to allow unmount/export Don't add non-disk names such as "mirror" or "raidz" to $DISKS Use $TEST_BASE_DIR instead of /tmp Increase HZ from 100 to 1000 which is more common on Linux removal_multiple_indirection.ksh Reduce iterations in order to not time out on the code coverage builders. removal_resume_export: Functionally, the test case is correct but there exists a race where the kernel thread hasn't been fully started yet and is not visible. Wait for up to 1 second for the removal thread to be started before giving up on it. Also, increase the amount of data copied in order that the removal not finish before the export has a chance to fail. * MMP compatibility, the concept of concrete versus non-concrete devices has slightly changed the semantics of vdev_writeable(). Update mmp_random_leaf_impl() accordingly. * Updated dbuf_remap() to handle the org.zfsonlinux:large_dnode pool feature which is not supported by OpenZFS. * Added support for new vdev removal tracepoints. * Test cases removal_with_zdb and removal_condense_export have been intentionally disabled. When run manually they pass as intended, but when running in the automated test environment they produce unreliable results on the latest Fedora release. They may work better once the upstream pool import refectoring is merged into ZoL at which point they will be re-enabled. Authored by: Matthew Ahrens <[email protected]> Reviewed-by: Alex Reece <[email protected]> Reviewed-by: George Wilson <[email protected]> Reviewed-by: John Kennedy <[email protected]> Reviewed-by: Prakash Surya <[email protected]> Reviewed by: Richard Laager <[email protected]> Reviewed by: Tim Chase <[email protected]> Reviewed by: Brian Behlendorf <[email protected]> Approved by: Garrett D'Amore <[email protected]> Ported-by: Tim Chase <[email protected]> Signed-off-by: Tim Chase <[email protected]> OpenZFS-issue: https://www.illumos.org/issues/7614 OpenZFS-commit: https://github.com/openzfs/openzfs/commit/f539f1eb Closes #6900
* Illumos 5164-5165 - space map fixesMatthew Ahrens2014-10-231-11/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | 5164 space_map_max_blksz causes panic, does not work 5165 zdb fails assertion when run on pool with recently-enabled space map_histogram feature Reviewed by: Christopher Siden <[email protected]> Reviewed by: George Wilson <[email protected]> Reviewed by: Saso Kiselkov <[email protected]> Approved by: Dan McDonald <[email protected]> References: https://www.illumos.org/issues/5164 https://www.illumos.org/issues/5165 https://github.com/illumos/illumos-gate/commit/b1be289 Porting Notes: The metaslab_fragmentation() hunk was dropped from this patch because it was already resolved by commit 8b0a084. The comment modified in metaslab.c was updated to use the correct variable name, space_map_blksz. The upstream commit incorrectly used space_map_blksize. Ported by: Turbo Fredriksson <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #2697
* Illumos 4976-4984 - metaslab improvementsGeorge Wilson2014-08-181-5/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 4976 zfs should only avoid writing to a failing non-redundant top-level vdev 4978 ztest fails in get_metaslab_refcount() 4979 extend free space histogram to device and pool 4980 metaslabs should have a fragmentation metric 4981 remove fragmented ops vector from block allocator 4982 space_map object should proactively upgrade when feature is enabled 4983 need to collect metaslab information via mdb 4984 device selection should use fragmentation metric Reviewed by: Matthew Ahrens <[email protected]> Reviewed by: Adam Leventhal <[email protected]> Reviewed by: Christopher Siden <[email protected]> Approved by: Garrett D'Amore <[email protected]> References: https://www.illumos.org/issues/4976 https://www.illumos.org/issues/4978 https://www.illumos.org/issues/4979 https://www.illumos.org/issues/4980 https://www.illumos.org/issues/4981 https://www.illumos.org/issues/4982 https://www.illumos.org/issues/4983 https://www.illumos.org/issues/4984 https://github.com/illumos/illumos-gate/commit/2e4c998 Notes: The "zdb -M" option has been re-tasked to display the new metaslab fragmentation metric and the new "zdb -I" option is used to control the maximum number of in-flight I/Os. The new fragmentation metric is derived from the space map histogram which has been rolled up to the vdev and pool level and is presented to the user via "zpool list". Add a number of module parameters related to the new metaslab weighting logic. Ported by: Tim Chase <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #2595
* Illumos #4101, #4102, #4103, #4105, #4106George Wilson2014-07-221-88/+78
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 4101 metaslab_debug should allow for fine-grained control 4102 space_maps should store more information about themselves 4103 space map object blocksize should be increased 4105 removing a mirrored log device results in a leaked object 4106 asynchronously load metaslab Reviewed by: Matthew Ahrens <[email protected]> Reviewed by: Adam Leventhal <[email protected]> Reviewed by: Sebastien Roy <[email protected]> Approved by: Garrett D'Amore <[email protected]> Prior to this patch, space_maps were preferred solely based on the amount of free space left in each. Unfortunately, this heuristic didn't contain any information about the make-up of that free space, which meant we could keep preferring and loading a highly fragmented space map that wouldn't actually have enough contiguous space to satisfy the allocation; then unloading that space_map and repeating the process. This change modifies the space_map's to store additional information about the contiguous space in the space_map, so that we can use this information to make a better decision about which space_map to load. This requires reallocating all space_map objects to increase their bonus buffer size sizes enough to fit the new metadata. The above feature can be enabled via a new feature flag introduced by this change: com.delphix:spacemap_histogram In addition to the above, this patch allows the space_map block size to be increase. Currently the block size is set to be 4K in size, which has certain implications including the following: * 4K sector devices will not see any compression benefit * large space_maps require more metadata on-disk * large space_maps require more time to load (typically random reads) Now the space_map block size can adjust as needed up to the maximum size set via the space_map_max_blksz variable. A bug was fixed which resulted in potentially leaking an object when removing a mirrored log device. The previous logic for vdev_remove() did not deal with removing top-level vdevs that are interior vdevs (i.e. mirror) correctly. The problem would occur when removing a mirrored log device, and result in the DTL space map object being leaked; because top-level vdevs don't have DTL space map objects associated with them. References: https://www.illumos.org/issues/4101 https://www.illumos.org/issues/4102 https://www.illumos.org/issues/4103 https://www.illumos.org/issues/4105 https://www.illumos.org/issues/4106 https://github.com/illumos/illumos-gate/commit/0713e23 Porting notes: A handful of kmem_alloc() calls were converted to kmem_zalloc(). Also, the KM_PUSHPAGE and TQ_PUSHPAGE flags were used as necessary. Ported-by: Tim Chase <[email protected]> Signed-off-by: Prakash Surya <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #2488
* Illumos #3742Will Andrews2013-11-041-1/+0
| | | | | | | | | | | | | | | | | | | | | 3742 zfs comments need cleaner, more consistent style Reviewed by: Matthew Ahrens <[email protected]> Reviewed by: George Wilson <[email protected]> Reviewed by: Eric Schrock <[email protected]> Approved by: Christopher Siden <[email protected]> References: https://www.illumos.org/issues/3742 illumos/illumos-gate@f7170741490edba9d1d9c697c177c887172bc741 Ported-by: Richard Yao <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Issue #1775 Porting notes: 1. The change to zfs_vfsops.c was dropped because it involves zfs_mount_label_policy, which does not exist in the Linux port.
* Illumos #3464Matthew Ahrens2013-09-041-0/+2
| | | | | | | | | | | | | | | | | 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 #3552, #3564George Wilson2013-06-191-3/+4
| | | | | | | | | | | | | | | | | | 3552 condensing one space map burns 3 seconds of CPU in spa_sync() thread 3564 spa_sync() spends 5-10% of its time in metaslab_sync() (when not condensing) Reviewed by: Adam Leventhal <[email protected]> Reviewed by: Dan Kimmel <[email protected]> Reviewed by: Matthew Ahrens <[email protected]> Approved by: Richard Lowe <[email protected]> References: illumos/illumos-gate@16a4a8074274d2d7cc408589cf6359f4a378c861 https://www.illumos.org/issues/3552 https://www.illumos.org/issues/3564 Ported-by: Tim Chase <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #1513
* Illumos #3329, #3330, #3331, #3335George Wilson2013-05-061-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | 3329 spa_sync() spends 10-20% of its time in spa_free_sync_cb() 3330 space_seg_t should have its own kmem_cache 3331 deferred frees should happen after sync_pass 1 3335 make SYNC_PASS_* constants tunable Reviewed by: Adam Leventhal <[email protected]> Reviewed by: Matt Ahrens <[email protected]> Reviewed by: Christopher Siden <[email protected]> Reviewed by: Eric Schrock <[email protected]> Reviewed by: Richard Lowe <[email protected]> Reviewed by: Dan McDonald <[email protected]> Approved by: Eric Schrock <[email protected]> References: illumos/illumos-gate@01f55e48fb4d524eaf70687728aa51b7762e2e97 https://www.illumos.org/issues/3329 https://www.illumos.org/issues/3330 https://www.illumos.org/issues/3331 https://www.illumos.org/issues/3335 Ported-by: Brian Behlendorf <[email protected]>
* Constify structures containing function pointersRichard Yao2013-03-041-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The PaX team modified the kernel's modpost to report writeable function pointers as section mismatches because they are potential exploit targets. We could ignore the warnings, but their presence can obscure actual issues. Proper const correctness can also catch programming mistakes. Building the kernel modules against a PaX/GrSecurity patched Linux 3.4.2 kernel reports 133 section mismatches prior to this patch. This patch eliminates 130 of them. The quantity of writeable function pointers eliminated by constifying each structure is as follows: vdev_opts_t 52 zil_replay_func_t 24 zio_compress_info_t 24 zio_checksum_info_t 9 space_map_ops_t 7 arc_byteswap_func_t 5 The remaining 3 writeable function pointers cannot be addressed by this patch. 2 of them are in zpl_fs_type. The kernel's sget function requires that this be non-const. The final writeable function pointer is created by SPL_SHRINKER_DECLARE. The kernel's set_shrinker() and remove_shrinker() functions also require that this be non-const. Signed-off-by: Richard Yao <[email protected]> Signed-off-by: Brian Behlendorf <[email protected]> Closes #1300
* Support custom build directories and move includesBrian Behlendorf2010-09-081-0/+179
One of the neat tricks an autoconf style project is capable of is allow configurion/building in a directory other than the source directory. The major advantage to this is that you can build the project various different ways while making changes in a single source tree. For example, this project is designed to work on various different Linux distributions each of which work slightly differently. This means that changes need to verified on each of those supported distributions perferably before the change is committed to the public git repo. Using nfs and custom build directories makes this much easier. I now have a single source tree in nfs mounted on several different systems each running a supported distribution. When I make a change to the source base I suspect may break things I can concurrently build from the same source on all the systems each in their own subdirectory. wget -c http://github.com/downloads/behlendorf/zfs/zfs-x.y.z.tar.gz tar -xzf zfs-x.y.z.tar.gz cd zfs-x-y-z ------------------------- run concurrently ---------------------- <ubuntu system> <fedora system> <debian system> <rhel6 system> mkdir ubuntu mkdir fedora mkdir debian mkdir rhel6 cd ubuntu cd fedora cd debian cd rhel6 ../configure ../configure ../configure ../configure make make make make make check make check make check make check This change also moves many of the include headers from individual incude/sys directories under the modules directory in to a single top level include directory. This has the advantage of making the build rules cleaner and logically it makes a bit more sense.