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Alexander Motin 588fa16830 ZAP: Reduce leaf array and free chunks fragmentation
Previous implementation of zap_leaf_array_free() put chunks on the
free list in reverse order.  Also zap_leaf_transfer_entry() and
zap_entry_remove() were freeing name and value arrays in reverse
order.  Together this created a mess in the free list, making
following allocations much more fragmented than necessary.

This patch re-implements zap_leaf_array_free() to keep existing
chunks order, and implements non-destructive zap_leaf_array_copy()
to be used in zap_leaf_transfer_entry() to allow properly ordered
freeing name and value arrays there and in zap_entry_remove().

With this change test of some writes and deletes shows percent of
non-contiguous chunks in DDT reducing from 61% and 47% to 0% and
17% for arrays and frees respectively.  Sure some explicit sorting
could do even better, especially for ZAPs with variable-size arrays,
but it would also cost much more, while this should be very cheap.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Alexander Motin <mav@FreeBSD.org>
Sponsored by:	iXsystems, Inc.
Closes #16766
(cherry picked from commit 9a81484e35)
2025-05-28 16:00:28 -07:00
.github CI: Add Fedora 42 runner (#17249) 2025-04-22 12:29:07 -07:00
cmd GCC 15: Fix unterminated-string-initialization (#17244) 2025-04-16 09:59:45 -07:00
config config: fix ZFS_LINUX_TEST_RESULT_SYMBOL with --enable-linux-builtin 2025-04-16 09:59:45 -07:00
contrib debian: Add libtirpc-dev dependency (#17220) 2025-04-16 09:59:45 -07:00
etc SPDX: license tags: MIT 2025-04-16 09:59:44 -07:00
include Fix FDT rollback to not overwrite unnecessary fields (#17205) 2025-04-16 09:59:45 -07:00
lib Fix memory leaks in pool properties handling 2025-04-16 09:59:45 -07:00
man Disambiguate reference to kibibytes, not kilobytes 2025-04-16 09:59:45 -07:00
module ZAP: Reduce leaf array and free chunks fragmentation 2025-05-28 16:00:28 -07:00
rpm RPM: Hold back incompatible kernel packages on Fedora 2025-04-30 10:58:28 -07:00
scripts ZTS: Fix zpool_status_features_001_pos local test (#17174) 2025-04-16 09:59:45 -07:00
tests GCC 15: Fix unterminated-string-initialization (#17244) 2025-04-16 09:59:45 -07:00
udev SPDX: license tags: CDDL-1.0 2025-04-16 09:59:44 -07:00
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.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
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configure.ac SPDX: license tags: CDDL-1.0 2025-04-16 09:59:44 -07:00
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LICENSE Update build system and packaging 2018-05-29 16:00:33 -07:00
Makefile.am spdxcheck: program to check SPDX license tags 2025-04-16 09:59:45 -07:00
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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 FreeBSD: remove support for FreeBSD < 13.0-RELEASE (#16372) 2024-08-05 16:56:45 -07:00
RELEASES.md Update RELEASES.md LTS release to 2.2 2025-02-25 22:27:10 +05:00
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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 13.0-RELEASE.