freebsd-nq/include/sys
Adam Leventhal 7ef5e54e2e Illumos #3581 spa_zio_taskq[ZIO_TYPE_FREE][ZIO_TASKQ_ISSUE]->tq_lock contention
3581 spa_zio_taskq[ZIO_TYPE_FREE][ZIO_TASKQ_ISSUE]->tq_lock is piping hot

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Christopher Siden <christopher.siden@delphix.com>
Reviewed by: Gordon Ross <gordon.ross@nexenta.com>
Approved by: Richard Lowe <richlowe@richlowe.net>

References:
  illumos/illumos-gate@ec94d32
  https://illumos.org/issues/3581

Notes for Linux port:

Earlier commit 08d08eb reduced contention on this taskq lock by simply
reducing the number of z_fr_iss threads from 100 to one-per-CPU.  We
also optimized the taskq implementation in zfsonlinux/spl@3c6ed54.
These changes significantly improved unlink performance to acceptable
levels.

This patch further reduces time spent spinning on this lock by
randomly dispatching the work items over multiple independent task
queues.  The Illumos ZFS developers stated that this lock contention
only arose after "3329 spa_sync() spends 10-20% of its time in
spa_free_sync_cb()" was landed.  It's not clear if 3329 affects the
Linux port or not.  I didn't see spa_free_sync_cb() show up in
oprofile sessions while unlinking large files, but I may just not
have used the right test case.

I tested unlinking a 1 TB of data with and without the patch and
didn't observe a meaningful difference in elapsed time.  However,
oprofile showed that the percent time spent in taskq_thread() was
reduced from about 16% to about 5%.  Aside from a possible slight
performance benefit this may be worth landing if only for the sake of
maintaining consistency with upstream.

Ported-by: Ned Bass <bass6@llnl.gov>
Closes #1327
2013-05-06 14:05:37 -07:00
..
fm 3246 ZFS I/O deadman thread 2013-05-01 17:05:52 -07:00
fs Change zfs-kmod-devel install path 2013-03-13 13:42:16 -07:00
arc.h Illumos #3145, #3212 2013-01-08 10:35:44 -08:00
avl_impl.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
avl.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
bplist.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
bpobj.h Illumos #3104: eliminate empty bpobjs 2013-01-08 10:35:43 -08:00
bptree.h Illumos #2619 and #2747 2013-01-08 10:35:35 -08:00
dbuf.h Switch KM_SLEEP to KM_PUSHPAGE 2012-08-27 12:01:37 -07:00
ddt.h Add ddt_object_count() error handling 2012-10-29 08:57:45 -07:00
dmu_impl.h Illumos #2703: add mechanism to report ZFS send progress 2012-09-19 13:39:06 -07:00
dmu_objset.h Illumos #3100: zvol rename fails with EBUSY when dirty. 2012-10-03 13:59:02 -07:00
dmu_traverse.h Illumos #2619 and #2747 2013-01-08 10:35:35 -08:00
dmu_tx.h Add --enable-debug-dmu-tx configure option 2012-03-23 12:25:17 -07:00
dmu_zfetch.h Add missing ZFS tunables 2011-05-04 10:02:37 -07:00
dmu.h build: resolve orthographic and other grammatical errors 2013-04-02 10:44:52 -07:00
dnode.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
dsl_dataset.h Use dsl_dataset_snap_lookup() 2013-01-25 15:07:40 -08:00
dsl_deadlist.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
dsl_deleg.h Illumos #1644, #1645, #1646, #1647, #1708 2012-07-31 09:25:30 -07:00
dsl_dir.h Switch KM_SLEEP to KM_PUSHPAGE 2012-08-27 12:01:37 -07:00
dsl_pool.h 3246 ZFS I/O deadman thread 2013-05-01 17:05:52 -07:00
dsl_prop.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
dsl_scan.h Illumos #2619 and #2747 2013-01-08 10:35:35 -08:00
dsl_synctask.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
efi_partition.h Move partition scanning from userspace to module. 2012-07-17 09:17:31 -07:00
Makefile.am Change zfs-kmod-devel install path 2013-03-13 13:42:16 -07:00
metaslab_impl.h Illumos #3329, #3330, #3331, #3335 2013-05-06 12:39:34 -07:00
metaslab.h Add FASTWRITE algorithm for synchronous writes. 2012-10-17 08:56:41 -07:00
nvpair_impl.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
nvpair.h Illumos #2619 and #2747 2013-01-08 10:35:35 -08:00
refcount.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
rrwlock.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
sa_impl.h Illumos #3208 cross-endian incorrect user/group accounting 2013-01-14 09:32:22 -08:00
sa.h Add sa_spill_rele() interface 2012-03-07 16:28:00 -08:00
spa_boot.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
spa_impl.h Illumos #3581 spa_zio_taskq[ZIO_TYPE_FREE][ZIO_TASKQ_ISSUE]->tq_lock contention 2013-05-06 14:05:37 -07:00
spa.h Illumos #3329, #3330, #3331, #3335 2013-05-06 12:39:34 -07:00
space_map.h Illumos #3329, #3330, #3331, #3335 2013-05-06 12:39:34 -07:00
txg_impl.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
txg.h Illumos #3086: unnecessarily setting DS_FLAG_INCONSISTENT on async 2013-01-08 10:35:43 -08:00
u8_textprep_data.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
u8_textprep.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
uberblock_impl.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
uberblock.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
uio_impl.h Add basic uio support 2011-02-10 09:21:43 -08:00
unique.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
uuid.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
vdev_disk.h Linux 2.6.x compat, blkdev_compat.h 2011-02-23 12:29:38 -08:00
vdev_file.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
vdev_impl.h 3246 ZFS I/O deadman thread 2013-05-01 17:05:52 -07:00
vdev.h 3246 ZFS I/O deadman thread 2013-05-01 17:05:52 -07:00
xvattr.h Add xvattr support 2011-03-02 11:43:50 -08:00
zap_impl.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
zap_leaf.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
zap.h Illumos #3104: eliminate empty bpobjs 2013-01-08 10:35:43 -08:00
zfeature.h Illumos #2762: zpool command should have better support for feature flags 2013-01-08 10:35:43 -08:00
zfs_acl.h Fix build failures on PaX/GRSecurity patched kernels 2012-07-17 09:22:43 -07:00
zfs_context.h 3246 ZFS I/O deadman thread 2013-05-01 17:05:52 -07:00
zfs_ctldir.h Linux 3.7 compat, schedule_delayed_work() 2012-12-12 10:47:05 -08:00
zfs_debug.h Cleanly support debug packages 2012-02-27 14:08:17 -08:00
zfs_dir.h Prototype/structure update for Linux 2011-02-10 09:27:21 -08:00
zfs_fuid.h Prototype/structure update for Linux 2011-02-10 09:27:21 -08:00
zfs_ioctl.h 3246 ZFS I/O deadman thread 2013-05-01 17:05:52 -07:00
zfs_onexit.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
zfs_rlock.h Range lock performance improvements 2011-03-08 12:44:06 -08:00
zfs_sa.h Implement SA based xattrs 2011-11-28 15:45:51 -08:00
zfs_stat.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
zfs_vfsops.h Fix 'zfs rollback' on mounted file systems 2013-01-17 09:51:20 -08:00
zfs_vnops.h Update SAs when an inode is dirtied 2012-12-14 12:18:54 -08:00
zfs_znode.h Constify structures containing function pointers 2013-03-04 08:49:32 -08:00
zil_impl.h Illumos #3086: unnecessarily setting DS_FLAG_INCONSISTENT on async 2013-01-08 10:35:43 -08:00
zil.h Constify structures containing function pointers 2013-03-04 08:49:32 -08:00
zio_checksum.h Constify structures containing function pointers 2013-03-04 08:49:32 -08:00
zio_compress.h Constify structures containing function pointers 2013-03-04 08:49:32 -08:00
zio_impl.h Illumos #3329, #3330, #3331, #3335 2013-05-06 12:39:34 -07:00
zio.h 3246 ZFS I/O deadman thread 2013-05-01 17:05:52 -07:00
zpl.h Fix 'zfs rollback' on mounted file systems 2013-01-17 09:51:20 -08:00
zrlock.h Support custom build directories and move includes 2010-09-08 12:38:56 -07:00
zvol.h Add snapdev=[hidden|visible] dataset property 2013-03-05 12:37:54 -08:00