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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
cmd Illumos #3306, #3321 2013-05-03 16:53:52 -07:00
config Ensure --with-spl-timeout waits for spl_config.h and symvers 2013-05-02 15:40:44 -07:00
dracut Refresh dracut module setup 2013-03-21 12:51:06 -07:00
etc Possibility to disable (not start) zfs at bootup. 2013-04-24 16:18:44 -07:00
include Illumos #3581 spa_zio_taskq[ZIO_TYPE_FREE][ZIO_TASKQ_ISSUE]->tq_lock contention 2013-05-06 14:05:37 -07:00
lib Silence 'old_umask' uninit variable warning 2013-05-01 17:05:58 -07:00
man Illumos #3306, #3321 2013-05-03 16:53:52 -07:00
module Illumos #3581 spa_zio_taskq[ZIO_TYPE_FREE][ZIO_TASKQ_ISSUE]->tq_lock contention 2013-05-06 14:05:37 -07:00
patches Adding grub2 mkconfig support patch 2012-07-30 16:17:23 -07:00
rpm Fix various generic kmod RPM spec issues. 2013-04-24 16:18:42 -07:00
scripts build: resolve orthographic and other grammatical errors 2013-04-02 10:44:52 -07:00
udev Retire zpool_id infrastructure 2013-01-29 12:23:17 -08:00
.gitignore Ignore *.{deb,rpm,tar.gz} files in the top directory. 2013-04-24 16:18:59 -07:00
AUTHORS Fix minor typos and update marketing copy. 2013-03-21 12:51:06 -07:00
autogen.sh build: do not call boilerplate ourself 2013-04-02 10:55:20 -07:00
configure.ac Automake 1.10.1 compat: AM_SILENT_RULES 2013-04-02 16:05:45 -07:00
copy-builtin Consistent menuconfig name 2012-08-26 13:49:37 -07:00
COPYRIGHT Refresh links to web site 2013-03-06 15:46:41 -08:00
DISCLAIMER Fix minor typos and update marketing copy. 2013-03-21 12:51:06 -07:00
Makefile.am build: do not call boilerplate ourself 2013-04-02 10:55:20 -07:00
META Tag zfs-0.6.1 2013-03-26 08:50:29 -07:00
OPENSOLARIS.LICENSE Add CDDL license file 2008-12-01 14:49:34 -08:00
README.markdown Fix minor typos and update marketing copy. 2013-03-21 12:51:06 -07:00
zfs-script-config.sh.in Retire zpool_id infrastructure 2013-01-29 12:23:17 -08:00
zfs.release.in Move zfs.release generation to configure step 2012-07-12 12:22:51 -07:00

Native ZFS for Linux!

ZFS is an advanced file system and volume manager which was originally developed for Solaris and is now maintained by the Illumos community.

ZFS on Linux, which is also known as ZoL, is currently feature complete. It includes fully functional and stable SPA, DMU, ZVOL, and ZPL layers.

Full documentation for installing ZoL on your favorite Linux distribution can be found at: http://zfsonlinux.org