mirror_zfs/module/zfs
Matthew Ahrens 0dc2f70c5c OpenZFS 9486 - reduce memory used by device removal on fragmented pools
Device removal allocates a new location for each allocated segment on
the disk that's being removed.  Each allocation results in one entry in
the mapping table, which maps from old location + length to new
location.  When a fragmented disk is removed, this can result in a large
number of mapping entries, and thus a large amount of memory consumed by
the mapping table.  In the worst real-world cases, we've seen around 1GB
of RAM per 1TB of storage removed.

We can improve on this situation by allocating larger segments, which
span across both allocated and free regions of the device being removed.
By including free regions in the allocation (and thus mapping), we
reduce the number of mapping entries.  For example, if we have a 4K
allocation followed by 1K free and then 4K allocated, we would allocate
4+1+4 = 9KB, and then move the entire region (including allocated and
free parts).  In this case we used one mapping where previously we would
have used two, but often the ratio is much higher (up to 20:1 in
real-world use).  We then need to mark the regions that were free on the
removing device as free in the new locations, and also obsolete in the
mapping entry.

This method preserves the fragmentation of the removing device, rather
than consolidating its allocated space into a small number of chunks
where possible.  But it results in drastic reduction of memory used by
the mapping table - around 20x in the most-fragmented cases.

In the most fragmented real-world cases, this reduces memory used by the
mapping from ~1GB to ~50MB of RAM per 1TB of storage removed.  Less
fragmented cases will typically also see around 50-100MB of RAM per 1TB
of storage.

Porting notes:

* Add the following as module parameters:
    * zfs_condense_indirect_vdevs_enable
    * zfs_condense_max_obsolete_bytes

* Document the following module parameters:
   * zfs_condense_indirect_vdevs_enable
   * zfs_condense_max_obsolete_bytes
   * zfs_condense_min_mapping_bytes

Authored by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Brian Behlendorf <behlendorf1@llnl.gov>
Ported-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Tim Chase <tim@chase2k.com>

OpenZFS-issue: https://illumos.org/issues/9486
OpenZFS-commit: https://github.com/ahrens/illumos/commit/07152e142e44c
External-issue: DLPX-57962
Closes #7536
2018-05-24 10:18:07 -07:00
..
abd.c Update for cppcheck v1.80 2017-11-18 14:08:00 -08:00
arc.c Add support for decryption faults in zinject 2018-05-02 15:36:20 -07:00
blkptr.c Undo c89 workarounds to match with upstream 2017-11-04 13:25:13 -07:00
bplist.c Change KM_PUSHPAGE -> KM_SLEEP 2015-01-16 14:41:26 -08:00
bpobj.c OpenZFS 7614, 9064 - zfs device evacuation/removal 2018-04-14 12:16:17 -07:00
bptree.c Native Encryption for ZFS on Linux 2017-08-14 10:36:48 -07:00
bqueue.c Call cv_signal() with mutex held 2017-06-26 14:36:49 -07:00
dbuf_stats.c Add dbuf hash and dbuf cache kstats 2018-01-29 10:24:52 -08:00
dbuf.c assertion in arc_release() during encrypted receive 2018-04-17 11:06:54 -07:00
ddt_zap.c Change KM_PUSHPAGE -> KM_SLEEP 2015-01-16 14:41:26 -08:00
ddt.c OpenZFS 7614, 9064 - zfs device evacuation/removal 2018-04-14 12:16:17 -07:00
dmu_diff.c Fix issues found with zfs diff 2018-05-01 11:24:20 -07:00
dmu_object.c Fix object reclaim when using large dnodes 2018-04-17 11:13:57 -07:00
dmu_objset.c Adopt pyzfs from ClusterHQ 2018-05-01 10:33:35 -07:00
dmu_send.c OpenZFS 9256 - zfs send space estimation off by > 10% on some datasets 2018-05-08 08:59:24 -07:00
dmu_traverse.c Fix hung z_zvol tasks during 'zfs receive' 2018-03-30 12:10:01 -07:00
dmu_tx.c OpenZFS 7614, 9064 - zfs device evacuation/removal 2018-04-14 12:16:17 -07:00
dmu_zfetch.c OpenZFS 7614, 9064 - zfs device evacuation/removal 2018-04-14 12:16:17 -07:00
dmu.c assertion in arc_release() during encrypted receive 2018-04-17 11:06:54 -07:00
dnode_sync.c Raw sends must be able to decrease nlevels 2018-02-02 11:43:11 -08:00
dnode.c Fix object reclaim when using large dnodes 2018-04-17 11:13:57 -07:00
dsl_bookmark.c Undo c89 workarounds to match with upstream 2017-11-04 13:25:13 -07:00
dsl_crypt.c Add support for decryption faults in zinject 2018-05-02 15:36:20 -07:00
dsl_dataset.c OpenZFS 7614, 9064 - zfs device evacuation/removal 2018-04-14 12:16:17 -07:00
dsl_deadlist.c OpenZFS 7614, 9064 - zfs device evacuation/removal 2018-04-14 12:16:17 -07:00
dsl_deleg.c Performance optimization of AVL tree comparator functions 2016-08-31 14:35:34 -07:00
dsl_destroy.c OpenZFS 7614, 9064 - zfs device evacuation/removal 2018-04-14 12:16:17 -07:00
dsl_dir.c OpenZFS 7614, 9064 - zfs device evacuation/removal 2018-04-14 12:16:17 -07:00
dsl_pool.c OpenZFS 7614, 9064 - zfs device evacuation/removal 2018-04-14 12:16:17 -07:00
dsl_prop.c Native Encryption for ZFS on Linux 2017-08-14 10:36:48 -07:00
dsl_scan.c OpenZFS 9443 - panic when scrub a v10 pool 2018-05-04 10:47:10 -07:00
dsl_synctask.c Illumos 4951 - ZFS administrative commands should use reserved space 2015-05-04 09:41:10 -07:00
dsl_userhold.c Undo c89 workarounds to match with upstream 2017-11-04 13:25:13 -07:00
edonr_zfs.c DLPX-44812 integrate EP-220 large memory scalability 2016-11-29 14:34:27 -08:00
fm.c Linux 4.14 compat: CONFIG_GCC_PLUGIN_RANDSTRUCT 2017-11-28 17:33:48 -06:00
gzip.c Resolve QAT issues with incompressible data 2018-03-29 17:40:34 -07:00
hkdf.c Encryption patch follow-up 2017-10-11 16:54:48 -04:00
lz4.c Fix LZ4_uncompress_unknownOutputSize caused panic 2017-05-19 13:45:46 -07:00
lzjb.c Change KM_PUSHPAGE -> KM_SLEEP 2015-01-16 14:41:26 -08:00
Makefile.in OpenZFS 9079 - race condition in starting and ending condensing thread for indirect vdevs 2018-04-14 12:23:53 -07:00
metaslab.c Silence compile-time warning on unused variable 2018-05-01 11:15:54 -07:00
mmp.c module param callbacks check for initialized spa 2018-05-11 12:46:07 -07:00
multilist.c Undo c89 workarounds to match with upstream 2017-11-04 13:25:13 -07:00
pathname.c Add pn_alloc()/pn_free() functions 2016-04-21 09:49:25 -07:00
policy.c Take user namespaces into account in policy checks 2018-03-07 15:40:42 -08:00
qat_compress.c Fix inst_num overflow in qat_crypt.c 2018-05-01 20:44:24 -07:00
qat_crypt.c Fix inst_num overflow in qat_crypt.c 2018-05-01 20:44:24 -07:00
qat.c SHA256 QAT acceleration 2018-03-15 10:53:58 -07:00
qat.h Resolve QAT issues with incompressible data 2018-03-29 17:40:34 -07:00
range_tree.c OpenZFS 9486 - reduce memory used by device removal on fragmented pools 2018-05-24 10:18:07 -07:00
refcount.c Linux 4.11 compat: avoid refcount_t name conflict 2017-02-28 16:10:18 -08:00
rrwlock.c Fix spelling 2017-01-03 11:31:18 -06:00
sa.c Project Quota on ZFS 2018-02-13 14:54:54 -08:00
sha256.c SHA256 QAT acceleration 2018-03-15 10:53:58 -07:00
skein_zfs.c DLPX-44812 integrate EP-220 large memory scalability 2016-11-29 14:34:27 -08:00
spa_boot.c Add linux kernel module support 2010-08-31 13:41:58 -07:00
spa_config.c OpenZFS 9075 - Improve ZFS pool import/load process and corrupted pool recovery 2018-05-08 21:35:27 -07:00
spa_errlog.c Native Encryption for ZFS on Linux 2017-08-14 10:36:48 -07:00
spa_history.c Emit history events for 'zpool create' 2017-10-23 09:45:59 -07:00
spa_misc.c Unify behavior of deadman parameters 2018-05-08 21:45:47 -07:00
spa_stats.c Record skipped MMP writes in multihost_history 2018-03-06 15:15:15 -08:00
spa.c OpenZFS 9191 - dump vdev tree to zfs_dbgmsg when spa load fails due to missing log devices 2018-05-14 14:30:52 -04:00
space_map.c OpenZFS 7614, 9064 - zfs device evacuation/removal 2018-04-14 12:16:17 -07:00
space_reftree.c OpenZFS 7614, 9064 - zfs device evacuation/removal 2018-04-14 12:16:17 -07:00
trace.c OpenZFS 7614, 9064 - zfs device evacuation/removal 2018-04-14 12:16:17 -07:00
txg.c OpenZFS 7614, 9064 - zfs device evacuation/removal 2018-04-14 12:16:17 -07:00
uberblock.c Multi-modifier protection (MMP) 2017-07-13 13:54:00 -04:00
unique.c Performance optimization of AVL tree comparator functions 2016-08-31 14:35:34 -07:00
vdev_cache.c Undo c89 workarounds to match with upstream 2017-11-04 13:25:13 -07:00
vdev_disk.c module param callbacks check for initialized spa 2018-05-11 12:46:07 -07:00
vdev_file.c OpenZFS 7614, 9064 - zfs device evacuation/removal 2018-04-14 12:16:17 -07:00
vdev_indirect_births.c OpenZFS 7614, 9064 - zfs device evacuation/removal 2018-04-14 12:16:17 -07:00
vdev_indirect_mapping.c Revert "OpenZFS 9036 - zfs: duplicate 'const' declaration specifier" 2018-04-16 12:44:40 -07:00
vdev_indirect.c OpenZFS 9486 - reduce memory used by device removal on fragmented pools 2018-05-24 10:18:07 -07:00
vdev_label.c OpenZFS 9486 - reduce memory used by device removal on fragmented pools 2018-05-24 10:18:07 -07:00
vdev_mirror.c OpenZFS 9075 - Improve ZFS pool import/load process and corrupted pool recovery 2018-05-08 21:35:27 -07:00
vdev_missing.c OpenZFS 7614, 9064 - zfs device evacuation/removal 2018-04-14 12:16:17 -07:00
vdev_queue.c OpenZFS 7614, 9064 - zfs device evacuation/removal 2018-04-14 12:16:17 -07:00
vdev_raidz_math_aarch64_neon_common.h ABD raidz NEON support 2016-11-29 14:34:33 -08:00
vdev_raidz_math_aarch64_neon.c codebase style improvements for OpenZFS 6459 port 2017-01-22 13:25:40 -08:00
vdev_raidz_math_aarch64_neonx2.c ABD raidz NEON support 2016-11-29 14:34:33 -08:00
vdev_raidz_math_avx2.c ABD raidz avx512f support 2016-11-29 14:34:33 -08:00
vdev_raidz_math_avx512bw.c ABD: Adapt avx512bw raidz assembly 2016-12-15 17:31:33 -08:00
vdev_raidz_math_avx512f.c Use cstyle -cpP in make cstyle check 2016-12-12 10:46:26 -08:00
vdev_raidz_math_impl.h codebase style improvements for OpenZFS 6459 port 2017-01-22 13:25:40 -08:00
vdev_raidz_math_scalar.c ABD Vectorized raidz 2016-11-29 14:34:33 -08:00
vdev_raidz_math_sse2.c ABD raidz avx512f support 2016-11-29 14:34:33 -08:00
vdev_raidz_math_ssse3.c codebase style improvements for OpenZFS 6459 port 2017-01-22 13:25:40 -08:00
vdev_raidz_math.c OpenZFS 7431 - ZFS Channel Programs 2018-02-08 15:28:18 -08:00
vdev_raidz.c OpenZFS 7614, 9064 - zfs device evacuation/removal 2018-04-14 12:16:17 -07:00
vdev_removal.c OpenZFS 9486 - reduce memory used by device removal on fragmented pools 2018-05-24 10:18:07 -07:00
vdev_root.c OpenZFS 9075 - Improve ZFS pool import/load process and corrupted pool recovery 2018-05-08 21:35:27 -07:00
vdev.c OpenZFS 9189 - Add debug to vdev_label_read_config when txg check fails 2018-05-14 14:32:49 -04:00
zap_leaf.c Fix ENOSPC in "Handle zap_add() failures in ..." 2018-04-18 14:19:50 -07:00
zap_micro.c Fix ENOSPC in "Handle zap_add() failures in ..." 2018-04-18 14:19:50 -07:00
zap.c Fix ENOSPC in "Handle zap_add() failures in ..." 2018-04-18 14:19:50 -07:00
zcp_get.c Fix coverity defects: zfs channel programs 2018-02-20 11:19:42 -08:00
zcp_global.c OpenZFS 8600 - ZFS channel programs - snapshot 2018-02-08 15:29:24 -08:00
zcp_iter.c OpenZFS 7431 - ZFS Channel Programs 2018-02-08 15:28:18 -08:00
zcp_synctask.c Fix coverity defects: zfs channel programs 2018-02-20 11:19:42 -08:00
zcp.c OpenZFS 8677 - Open-Context Channel Programs 2018-02-08 16:05:57 -08:00
zfeature.c Undo c89 workarounds to match with upstream 2017-11-04 13:25:13 -07:00
zfs_acl.c OpenZFS 9213 - zfs: sytem typo 2018-04-15 10:59:13 -07:00
zfs_byteswap.c Add linux kernel module support 2010-08-31 13:41:58 -07:00
zfs_ctldir.c Use SET_ERROR for constant non-zero return codes 2017-08-02 21:16:12 -07:00
zfs_debug.c enable zfs_dbgmsg() by default, without dprintf() 2018-03-21 15:37:32 -07:00
zfs_dir.c Fix ENOSPC in "Handle zap_add() failures in ..." 2018-04-18 14:19:50 -07:00
zfs_fm.c Decryption error handling improvements 2018-03-31 11:12:51 -07:00
zfs_fuid.c Rename zfs_sb_t -> zfsvfs_t 2017-03-10 09:51:33 -08:00
zfs_ioctl.c Fix 'zpool create -t <tempname>' 2018-05-07 21:11:58 -07:00
zfs_log.c Project Quota on ZFS 2018-02-13 14:54:54 -08:00
zfs_onexit.c zfsdev_getminor() should check for invalid file handles 2015-06-22 17:02:13 -07:00
zfs_ratelimit.c Change checksum & IO delay ratelimit values 2018-03-04 17:34:51 -08:00
zfs_replay.c Project Quota on ZFS 2018-02-13 14:54:54 -08:00
zfs_rlock.c Fix spelling 2017-01-03 11:31:18 -06:00
zfs_sa.c Project Quota on ZFS 2018-02-13 14:54:54 -08:00
zfs_vfsops.c ZIL claiming should not start user accounting 2018-02-20 16:27:31 -08:00
zfs_vnops.c RHEL 7.5 compat: FMODE_KABI_ITERATE 2018-05-02 15:01:24 -07:00
zfs_znode.c OpenZFS 9421, 9422 - zdb show possibly leaked objects 2018-05-04 10:50:24 -07:00
zil.c OpenZFS 7614, 9064 - zfs device evacuation/removal 2018-04-14 12:16:17 -07:00
zio_checksum.c Undo c89 workarounds to match with upstream 2017-11-04 13:25:13 -07:00
zio_compress.c Undo c89 workarounds to match with upstream 2017-11-04 13:25:13 -07:00
zio_crypt.c Add support for decryption faults in zinject 2018-05-02 15:36:20 -07:00
zio_inject.c Add support for decryption faults in zinject 2018-05-02 15:36:20 -07:00
zio.c OpenZFS 9075 - Improve ZFS pool import/load process and corrupted pool recovery 2018-05-08 21:35:27 -07:00
zle.c Fix zle_decompress out of bound access 2018-02-09 10:08:05 -08:00
zpl_ctldir.c RHEL 7.5 compat: FMODE_KABI_ITERATE 2018-05-02 15:01:24 -07:00
zpl_export.c Use cstyle -cpP in make cstyle check 2016-12-12 10:46:26 -08:00
zpl_file.c RHEL 7.5 compat: FMODE_KABI_ITERATE 2018-05-02 15:01:24 -07:00
zpl_inode.c Linux 4.12 compat: CURRENT_TIME removed 2017-05-10 09:30:48 -07:00
zpl_super.c Allow mounting datasets more than once 2018-04-13 10:44:05 -07:00
zpl_xattr.c Update for cppcheck v1.80 2017-11-18 14:08:00 -08:00
zrlock.c Fix race in trace point in zrl_add_impl 2018-03-12 11:27:02 -07:00
zthr.c Avoid Linux hung task message in ZTHR 2018-04-15 15:12:28 -07:00
zvol.c Linux compat 4.16: blk_queue_flag_{set,clear} 2018-04-10 10:32:14 -07:00