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
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linux	Change zfs-kmod-devel install path	2013-03-13 13:42:16 -07:00
sys	Illumos #3581 spa_zio_taskq[ZIO_TYPE_FREE][ZIO_TASKQ_ISSUE]->tq_lock contention	2013-05-06 14:05:37 -07:00
libnvpair.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
libuutil_common.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
libuutil_impl.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
libuutil.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
libzfs_impl.h	Illumos #1644, #1645, #1646, #1647, #1708	2012-07-31 09:25:30 -07:00
libzfs.h	Retire zpool_id infrastructure	2013-01-29 12:23:17 -08:00
Makefile.am	Change zfs-kmod-devel install path	2013-03-13 13:42:16 -07:00
zfeature_common.h	Illumos #3035 LZ4 compression support in ZFS and GRUB	2013-01-29 09:28:20 -08:00
zfs_comutil.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
zfs_deleg.h	Illumos #278: get rid zfs of python and pyzfs dependencies	2011-08-01 12:09:36 -07:00
zfs_fletcher.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
zfs_namecheck.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
zfs_prop.h	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
zpios-ctl.h	Refresh links to web site	2013-03-06 15:46:41 -08:00
zpios-internal.h	Refresh links to web site	2013-03-06 15:46:41 -08:00