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Alexander Motin
c2668b2d10
Before this change zfs_metaslab_switch_threshold tunable switched metaslabs each time ones index reduced by two (which means biggest contiguous chunk reduced to 1/4). It is a good idea to balance metaslabs fragmentation. But for empty metaslabs (having power- of-2 sizes) this means switching when they get just below the half of their capacity. Inspection with zdb after filling new pool to half capacity shown most of its metaslabs filled to half capacity. I consider this sub-optimal for pool fragmentation in a long run. This change blocks the metaslabs switching if most of the metaslab free space (15/16) is represented by a single contiguous range. Such metaslab should not be considered fragmented until it actually fail some big allocation. More contiguous filling should improve data locality and increase time before previously filled and partially freed metaslab is touched again, giving it more time to free more contiguous chunks for lower fragmentation. It should also slightly reduce spacemap traffic. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Paul Dagnelie <pcd@delphix.com> Signed-off-by: Alexander Motin <mav@FreeBSD.org> Sponsored by: iXsystems, Inc. Closes #17081
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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Full documentation for installing OpenZFS on your favorite operating system can be found at the Getting Started Page.
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We have a separate document with contribution guidelines.
We have a Code of Conduct.
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OpenZFS is released under a CDDL license.
For more details see the NOTICE, LICENSE and COPYRIGHT files; UCRL-CODE-235197
Supported Kernels
- The
METAfile contains the officially recognized supported Linux kernel versions. - Supported FreeBSD versions are any supported branches and releases starting from 13.0-RELEASE.