Go to file
Debabrata Banerjee 44813aefad Don't run the reaper if we didn't shrink the cache
Calling it when nothing is evictable will cause extra kswapd cpu. Also
if we didn't shrink it's unlikely to have memory to reap because we
likely just called it microseconds ago. The exception is if we are in
direct reclaim.

You can see how hard this is being hit in kswapd with a light test
workload:

  34.95%  [zfs]             [k] arc_kmem_reap_now
   5.40%  [spl]             [k] spl_kmem_cache_reap_now
   3.79%  [kernel]          [k] _raw_spin_lock
   2.86%  [spl]             [k] __spl_kmem_cache_generic_shrinker.isra.7
   2.70%  [kernel]          [k] shrink_slab.part.37
   1.93%  [kernel]          [k] isolate_lru_pages.isra.43
   1.55%  [kernel]          [k] __wake_up_bit
   1.20%  [kernel]          [k] super_cache_count
   1.20%  [kernel]          [k] __radix_tree_lookup

With ZFS just mounted but only ext4/pagecache memory pressure
arc_kmem_reap_now still consumes excessive CPU:

  12.69%  [kernel]  [k] isolate_lru_pages.isra.43
  10.76%  [kernel]  [k] free_pcppages_bulk
   7.98%  [kernel]  [k] drop_buffers
   7.31%  [kernel]  [k] shrink_page_list
   6.44%  [zfs]     [k] arc_kmem_reap_now
   4.19%  [kernel]  [k] free_hot_cold_page
   4.00%  [kernel]  [k] __slab_free
   3.95%  [kernel]  [k] __isolate_lru_page
   3.09%  [kernel]  [k] __radix_tree_lookup

Same pagecache only workload as above with this patch series:

  11.58%  [kernel]  [k] isolate_lru_pages.isra.43
  11.20%  [kernel]  [k] drop_buffers
   9.67%  [kernel]  [k] free_pcppages_bulk
   8.44%  [kernel]  [k] shrink_page_list
   4.86%  [kernel]  [k] __isolate_lru_page
   4.43%  [kernel]  [k] free_hot_cold_page
   4.00%  [kernel]  [k] __slab_free
   3.44%  [kernel]  [k] __radix_tree_lookup

   (arc_kmem_reap_now has 0 samples in perf)

AKAMAI: zfs: CR 3695042
Reviewed-by: Tim Chase <tim@chase2k.com>
Reviewed-by: Richard Yao <ryao@gentoo.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Debabrata Banerjee <dbanerje@akamai.com>
Issue #6035
2017-05-02 15:50:13 -04:00
.github Commit message format in contributing guidelines 2017-03-31 09:33:38 -07:00
cmd OpenZFS 7252 - compressed zfs send / receive 2017-04-26 12:31:43 -07:00
config Linux 4.12 compat: super_setup_bdi_name() 2017-05-02 09:46:18 -07:00
contrib Fix initramfs hook for merged /usr/lib and /lib 2017-02-27 12:03:23 -08:00
etc OpenZFS 7793 - ztest fails assertion in dmu_tx_willuse_space 2017-03-07 09:51:59 -08:00
include Linux 4.12 compat: super_setup_bdi_name() 2017-05-02 09:46:18 -07:00
lib OpenZFS 7252 - compressed zfs send / receive 2017-04-26 12:31:43 -07:00
man Reinstate zvol_taskq to fix aio on zvol 2017-04-26 13:54:40 -07:00
module Don't run the reaper if we didn't shrink the cache 2017-05-02 15:50:13 -04:00
rpm Prebaked scripts for zpool status/iostat -c 2017-04-21 09:27:04 -07:00
scripts OpenZFS 7503 - zfs-test should tail ::zfs_dbgmsg on test failure 2017-04-12 13:36:48 -07:00
tests OpenZFS 7252 - compressed zfs send / receive 2017-04-26 12:31:43 -07:00
udev Fix spelling 2017-01-03 11:31:18 -06:00
.gitignore OpenZFS 7290 - ZFS test suite needs to control what utilities it can run 2017-04-06 09:25:36 -07:00
.gitmodules Add zimport.sh compatibility test script 2014-02-21 12:10:31 -08:00
AUTHORS Add a missing > to AUTHORS 2014-09-02 14:18:53 -07:00
autogen.sh build: do not call boilerplate ourself 2013-04-02 10:55:20 -07:00
configure.ac OpenZFS 7503 - zfs-test should tail ::zfs_dbgmsg on test failure 2017-04-12 13:36:48 -07:00
copy-builtin Allow c99 when building ZFS in the kernel tree 2017-03-27 12:31:15 -07:00
COPYRIGHT Update ZED copyright boilerplate 2015-05-11 15:07:00 -07:00
DISCLAIMER Fix minor typos and update marketing copy. 2013-03-21 12:51:06 -07:00
Makefile.am Prebaked scripts for zpool status/iostat -c 2017-04-21 09:27:04 -07:00
META Tag 0.7.0-rc3 2017-01-20 10:18:28 -08:00
OPENSOLARIS.LICENSE Add CDDL license file 2008-12-01 14:49:34 -08:00
README.markdown Add CONTRIBUTING information and templates 2016-12-09 12:48:12 -07:00
TEST Skip xfstests on Amazon Linux 2017-04-06 17:15:30 -07:00
zfs-script-config.sh.in Prebaked scripts for zpool status/iostat -c 2017-04-21 09:27:04 -07:00
zfs.release.in Move zfs.release generation to configure step 2012-07-12 12:22:51 -07:00

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. And it's native!

Official Resources

Installation

Full documentation for installing ZoL on your favorite Linux distribution can be found at our site.

Contribute & Develop

We have a separate document with contribution guidelines.