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Matthew Ahrens 2adc6b35ae Missed wakeup when growing kmem cache When growing the size of a (VMEM or KVMEM) kmem cache, spl_cache_grow() always does taskq_dispatch(spl_cache_grow_work), and then waits for the KMC_BIT_GROWING to be cleared by the taskq thread. The taskq thread (spl_cache_grow_work()) does: 1. allocate new slab and add to list 2. wake_up_all(skc_waitq) 3. clear_bit(KMC_BIT_GROWING) Therefore, the waiting thread can wake up before GROWING has been cleared. It will see that the growing has not yet completed, and go back to sleep until it hits the 100ms timeout. This can have an extreme performance impact on workloads that alloc/free more than fits in the (statically-sized) magazines. These workloads allocate and free slabs with high frequency. The problem can be observed with `funclatency spl_cache_grow`, which on some workloads shows that 99.5% of the time it takes <64us to allocate slabs, but we spend ~70% of our time in outliers, waiting for the 100ms timeout. The fix is to do `clear_bit(KMC_BIT_GROWING)` before `wake_up_all(skc_waitq)`. A future investigation should evaluate if we still actually need to taskq_dispatch() at all, and if so on which kernel versions. Reviewed-by: Paul Dagnelie <pcd@delphix.com> Reviewed-by: Pavel Zakharov <pavel.zakharov@delphix.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: George Wilson <gwilson@delphix.com> Signed-off-by: Matthew Ahrens <mahrens@delphix.com> Closes #9989		2020-02-13 11:23:02 -08:00
.github	Add an .editorconfig; document git whitespace settings	2020-01-27 13:32:52 -08:00
cmd	zdb: Always print symlink target	2020-02-12 11:36:05 -08:00
config	ICP: Improve AES-GCM performance	2020-02-10 12:59:50 -08:00
contrib	Implement bookmark copying	2020-02-11 13:19:12 -08:00
etc	Suggest using visudo to edit	2020-02-05 11:31:53 -08:00
include	Remove duplicate dbufs accounting	2020-02-13 11:20:42 -08:00
lib	Move zfs_version_kernel to platform code	2020-02-12 13:00:19 -08:00
man	zcp: add zfs.sync.bookmark	2020-02-11 13:19:17 -08:00
module	Missed wakeup when growing kmem cache	2020-02-13 11:23:02 -08:00
rpm	Change http://zfsonlinux.org links to https://zfsonlinux.org	2020-01-13 16:43:59 -08:00
scripts	bash scripts: use /usr/bin/env for bash shebangs	2020-02-10 13:13:46 -08:00
tests	ZTS: Move user_namespace test to linux.run	2020-02-12 13:06:00 -08:00
udev	Create symbolic links in /dev/disk/by-vdev for nvme disk devices	2019-12-17 17:50:20 -08:00
.editorconfig	Add an .editorconfig; document git whitespace settings	2020-01-27 13:32:52 -08:00
.gitignore	Adapt gitignore for modules	2019-12-02 13:23:47 -08:00
.gitmodules
.travis.yml
AUTHORS
autogen.sh
CODE_OF_CONDUCT.md
configure.ac	Tests for btree implementation used by range trees	2019-12-19 11:53:54 -08:00
copy-builtin	bash scripts: use /usr/bin/env for bash shebangs	2020-02-10 13:13:46 -08:00
COPYRIGHT	ICP: Improve AES-GCM performance	2020-02-10 12:59:50 -08:00
LICENSE
Makefile.am	Perform KABI checks in parallel	2019-10-01 12:50:34 -07:00
META	Update maximum kernel version to 5.4	2019-12-23 14:24:36 -08:00
NEWS
NOTICE
README.md	Change http://zfsonlinux.org links to https://zfsonlinux.org	2020-01-13 16:43:59 -08:00
TEST
zfs.release.in

README.md

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

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.

Release

ZFS on Linux is released under a CDDL license.
For more details see the NOTICE, LICENSE and COPYRIGHT files; UCRL-CODE-235197

Supported Kernels

The META file contains the officially recognized supported kernel versions.