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Brian Behlendorf 34dbc618f5
Reduce dbuf_find() lock contention
Holding a dbuf is a common operation which can become highly contended
in dbuf_find() when acquiring the dbuf hash mutex.  This is particularly
true on Linux when reading/writing volumes since by default up to 32
threads from the zvol_taskq may be taking a hold of the same dbuf.
This should also be observable on FreeBSD as long as there are enough
processes accessing the volume concurrently.

This is further aggregrated by the fact that only the block id will
be unique when calculating the dbuf hash for a single volume.  The
objset id, object id, and level will be the same for data blocks.
This has been observed to result in a somehwat less than uniform hash
distribution and a longer than expected max hash chain depth (~20)
on a large memory system (256 GB) using volumes.

This commit improves the siutation by switching the hash mutex to
an rwlock to allow concurrent lookups, and increasing DBUF_RWLOCKS
from 2048 to 8192 to further reduce the odds of a hash collision.

Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #13405
2022-05-04 11:17:29 -07:00
.github CI: Log test name to /dev/kmsg in ZTS 2022-03-24 08:01:26 -06:00
cmd zfs: holds: dequadratify 2022-04-27 11:55:40 -07:00
config Linux 5.18 compat: replace __set_page_dirty_nobuffers 2022-04-27 12:54:17 -07:00
contrib contrib: dracut: remove getargbool polyfill 2022-04-20 16:45:54 -07:00
etc linux: module: weld all but spl.ko into zfs.ko 2022-04-20 13:28:24 -07:00
include Reduce dbuf_find() lock contention 2022-05-04 11:17:29 -07:00
lib FreeBSD: Clean up the use of ioflags 2022-05-02 16:26:28 -07:00
man Default zfs_max_recordsize to 16M 2022-04-28 15:12:24 -07:00
module Reduce dbuf_find() lock contention 2022-05-04 11:17:29 -07:00
rpm linux: module: weld all but spl.ko into zfs.ko 2022-04-20 13:28:24 -07:00
scripts scripts: zfs.sh: explicitly unload all modules via rmmod 2022-04-21 16:33:12 -07:00
tests Speed up WB_SYNC_NONE when a WB_SYNC_ALL occurs simultaneously 2022-05-03 13:23:26 -07:00
udev Udev rules: remove zvol compat symlinks (without the leading zvol/) 2021-07-06 13:41:17 -07:00
.editorconfig Add an .editorconfig; document git whitespace settings 2020-01-27 13:32:52 -08:00
.gitignore Add FreeBSD support to OpenZFS 2020-04-14 11:36:28 -07:00
.gitmodules .gitmodules: link to openzfs github repository 2021-04-12 09:37:23 -07:00
AUTHORS Add zstd support to zfs 2020-08-20 10:30:06 -07:00
autogen.sh Cause autogen.sh to fail if autoreconf fails 2018-07-06 09:27:37 -07:00
CODE_OF_CONDUCT.md Replace ZFS on Linux references with OpenZFS 2020-10-08 20:10:13 -07:00
configure.ac linux: module: weld all but spl.ko into zfs.ko 2022-04-20 13:28:24 -07:00
copy-builtin copy-builtin: posix conformance 2021-05-08 08:58:26 -07:00
COPYRIGHT Fix typos 2020-06-09 21:24:09 -07:00
LICENSE Update build system and packaging 2018-05-29 16:00:33 -07:00
Makefile.am linux: module: weld all but spl.ko into zfs.ko 2022-04-20 13:28:24 -07:00
META Linux 5.17 compat: META 2022-03-23 08:52:30 -07:00
NEWS Fix NEWS file 2020-08-26 21:44:41 -07:00
NOTICE Update build system and packaging 2018-05-29 16:00:33 -07:00
README.md README: Update OpenZFS website url 2022-01-06 16:25:01 -08:00
RELEASES.md Add RELEASES.md file 2021-04-02 16:33:40 -07:00
TEST Remove CI builder customization from TEST 2020-03-16 10:46:03 -07:00
zfs.release.in Move zfs.release generation to configure step 2012-07-12 12:22:51 -07:00

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OpenZFS is an advanced file system and volume manager which was originally developed for Solaris and is now maintained by the OpenZFS community. This repository contains the code for running OpenZFS on Linux and FreeBSD.

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Official Resources

Installation

Full documentation for installing OpenZFS on your favorite operating system can be found at the Getting Started Page.

Contribute & Develop

We have a separate document with contribution guidelines.

We have a Code of Conduct.

Release

OpenZFS 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 Linux kernel versions.
  • Supported FreeBSD versions are any supported branches and releases starting from 12.2-RELEASE.