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Alexander Motin c1b5801bb5 Minimize aggsum_compare(&arc_size, arc_c) calls.
For busy ARC situation when arc_size close to arc_c is desired.  But
then it is quite likely that aggsum_compare(&arc_size, arc_c) will need
to flush per-CPU buckets to find exact comparison result.  Doing that
often in a hot path penalizes whole idea of aggsum usage there, since it
replaces few simple atomic additions with dozens of lock acquisitions.

Replacing aggsum_compare() with aggsum_upper_bound() in code increasing
arc_p when ARC is growing (arc_size < arc_c) according to PMC profiles
allows to save ~5% of CPU time in aggsum code during sequential write
to 12 ZVOLs with 16KB block size on large dual-socket system.

I suppose there some minor arc_p behavior change due to lower precision
of the new code, but I don't think it is a big deal, since it should
affect only very small window in time (aggsum buckets are flushed every
second) and in ARC size (buckets are limited to 10 average ARC blocks
per CPU).

Reviewed-by: Chris Dunlop <chris@onthe.net.au>
Reviewed-by: Richard Elling <Richard.Elling@RichardElling.com>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Allan Jude <allanjude@freebsd.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by:  Alexander Motin <mav@FreeBSD.org>
Closes #8901
2019-06-14 14:07:33 -07:00
.github Update CONTRIBUTING to point users to IRC as well as mailing list 2019-03-13 11:57:57 -07:00
cmd make zil max block size tunable 2019-06-10 11:48:42 -07:00
config Python config cleanup 2019-06-13 13:15:46 -07:00
contrib If $ZFS_BOOTFS contains guid, replace the guid portion with $pool 2019-06-06 13:04:35 -07:00
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lib Restrict filesystem creation if name referred either '.' or '..' 2019-06-13 08:56:15 -07:00
man panic in removal_remap test on 4K devices 2019-06-13 13:12:39 -07:00
module Minimize aggsum_compare(&arc_size, arc_c) calls. 2019-06-14 14:07:33 -07:00
rpm Add diffutils dependency for dkms build 2019-02-20 10:04:05 -08:00
scripts Fix %post and %postun generation in kmodtool 2019-06-10 09:06:58 -07:00
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zfs.release.in Move zfs.release generation to configure step 2012-07-12 12:22:51 -07:00

img

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.

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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.