05a7348a7e
RAIDZ parity is calculated by adding data one column at a time. It works OK for small blocks, but for large blocks results of previous addition may already be evicted from CPU caches to main memory, and in addition to extra memory write require extra read to get it back. This patch splits large parity operations into 64KB chunks, that should in most cases fit into CPU L2 caches from the last decade. I haven't touched more complicated cases of data reconstruction to not over complicate the code. Those should be relatively rare. My tests on Xeon Gold 6242R CPU with 1MB of L2 cache per core show up to 10/20% memory traffic reduction when writing to 4-wide RAIDZ/ RAIDZ2 blocks of ~4MB and up. Older CPUs with 256KB of L2 cache should see the effect even on smaller blocks. Wider vdevs may need bigger blocks to be affected. Reviewed-by: Brian Atkinson <batkinson@lanl.gov> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Alexander Motin <mav@FreeBSD.org> Sponsored by: iXsystems, Inc. Closes #15448 |
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README.md
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.
Official Resources
- Documentation - for using and developing this repo
- ZoL Site - Linux release info & links
- Mailing lists
- OpenZFS site - for conference videos and info on other platforms (illumos, OSX, Windows, etc)
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
METAfile contains the officially recognized supported Linux kernel versions. - Supported FreeBSD versions are any supported branches and releases starting from 12.2-RELEASE.