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Rob N 92dc4ad83d
Consider dnode_t allocations in dbuf cache size accounting
Entries in the dbuf cache contribute only the size of the dbuf data to
the cache size. Attached "user" data is not counted. This can lead to
the data currently "owned" by the cache consuming more memory accounting
appears to show. In some cases (eg a metadnode data block with all child
dnode_t slots allocated), the actual size can be as much as 3x as what
the cache believes it to be.

This is arguably correct behaviour, as the cache is only tracking the
size of the dbuf data, not even the overhead of the dbuf_t. On the other
hand, in the above case of dnodes, evicting cached metadnode dbufs is
the only current way to reclaim the dnode objects, and can lead to the
situation where the dbuf cache appears to be comfortably within its
target memory window and yet is holding enormous amounts of slab memory
that cannot be reclaimed.

This commit adds a facility for a dbuf user to artificially inflate the
apparent size of the dbuf for caching purposes. This at least allows for
cache tuning to be adjusted to match something closer to the real memory
overhead.

metadnode dbufs carry a >1KiB allocation per dnode in their user data.
This informs the dbuf cache machinery of that fact, allowing it to make
better decisions when evicting dbufs.

Sponsored-by: Klara, Inc.
Sponsored-by: Wasabi Technology, Inc.
Reviewed-by: Alexander Motin <mav@FreeBSD.org>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Rob Norris <rob.norris@klarasystems.com>
Closes #15511
2023-11-17 13:25:53 -08:00
.github Refine some details for the github actions update 2023-03-16 10:00:14 -07:00
cmd Consider dnode_t allocations in dbuf cache size accounting 2023-11-17 13:25:53 -08:00
config config/zfs-build.m4: add Gentoo's bash-completion path 2023-10-09 12:50:06 -07:00
contrib Packaging: Auto-generate changelog during configure (#15528) 2023-11-16 08:58:47 -08:00
etc Revert "systemd: Use non-absolute paths in Exec* lines" 2023-06-07 11:14:05 -07:00
include Consider dnode_t allocations in dbuf cache size accounting 2023-11-17 13:25:53 -08:00
lib Fix memory leak in zfs_setprocinit code 2023-11-17 13:21:04 -08:00
man Add a tunable to disable BRT support. 2023-11-16 11:35:22 -08:00
module Consider dnode_t allocations in dbuf cache size accounting 2023-11-17 13:25:53 -08:00
rpm Fix dkms installation of deb packages created with Alien. 2023-11-07 11:27:29 -08:00
scripts RAID-Z expansion feature 2023-11-08 10:19:41 -08:00
tests Add a tunable to disable BRT support. 2023-11-16 11:35:22 -08:00
udev Replace dead opensolaris.org license link 2022-07-11 14:16:13 -07:00
.cirrus.yml CI: add FreeBSD build with Cirrus CI 2023-10-06 08:50:26 -07:00
.editorconfig Add an .editorconfig; document git whitespace settings 2020-01-27 13:32:52 -08:00
.gitignore Packaging: Auto-generate changelog during configure (#15528) 2023-11-16 08:58:47 -08:00
.gitmodules .gitmodules: link to openzfs github repository 2021-04-12 09:37:23 -07:00
.mailmap mailmap: initial, trying to tidy up a lot of the commit history 2023-10-10 08:54:30 -07:00
AUTHORS AUTHORS: update with missing names 2023-10-10 08:55:42 -07:00
autogen.sh Ubuntu 22.04 integration: ShellCheck 2022-11-18 11:24:48 -08:00
CODE_OF_CONDUCT.md Documentation corrections 2022-12-22 11:34:28 -08:00
configure.ac Packaging: Auto-generate changelog during configure (#15528) 2023-11-16 08:58:47 -08:00
copy-builtin copy-builtin: add hooks with sed/>> 2022-05-10 10:17:43 -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 Process script directory for all configs 2022-10-27 16:45:14 -07:00
META Linux 6.6 compat: META 2023-11-14 09:55:28 -08:00
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.