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Reduce number of metaslab preload taskq threads. #15319

Merged
merged 1 commit into from
Oct 6, 2023
Merged

Reduce number of metaslab preload taskq threads. #15319

merged 1 commit into from
Oct 6, 2023

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@amotin amotin commented Sep 27, 2023 •
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Before this change ZFS created threads for 50% of CPUs for each top- level vdev. Plus it created the same number of threads for embedded log groups (that have only one metaslab and don't need any preload). As result, on system with 80 CPUs and pool of 60 vdevs this resulted in 4800 metaslab preload threads, that is absolutely insane.

This patch changes the preload threads to 50% of CPUs in one taskq per pool, so on the mentioned system it will be only 40 threads.

Among other things this fixes zdb on the mentioned system and pool on FreeBSD, that failed to create so many threads in one process.

Types of changes

  • Bug fix (non-breaking change which fixes an issue)
  • New feature (non-breaking change which adds functionality)
  • Performance enhancement (non-breaking change which improves efficiency)
  • Code cleanup (non-breaking change which makes code smaller or more readable)
  • Breaking change (fix or feature that would cause existing functionality to change)
  • Library ABI change (libzfs, libzfs_core, libnvpair, libuutil and libzfsbootenv)
  • Documentation (a change to man pages or other documentation)

Checklist:

@amotin
Reduce number of metaslab preload taskq threads.
97005fc 
Before this change ZFS created threads for 50% of CPUs for each top-
level vdev.  Plus it created the same number of threads for embedded
log groups (that have only one metaslab and don't need any preload).
As result, on system with 80 CPUs and pool of 60 vdevs this resulted
in 4800 metaslab preload threads, that is absolutely insane.

This patch changes the preload threads to 50% of CPUs in one taskq
per pool, so on the mentioned system it will be only 40 threads.

Among other things this fixes zdb on the mentioned system and pool
on FreeBSD, that failed to create so many threads in one process.

Signed-off-by:	Alexander Motin <[email protected]>
Sponsored by:	iXsystems, Inc.
@amotin amotin added the Status: Code Review Needed Ready for review and testing label Sep 27, 2023
@behlendorf behlendorf added Status: Accepted Ready to integrate (reviewed, tested) and removed Status: Code Review Needed Ready for review and testing labels Oct 6, 2023
@behlendorf behlendorf merged commit 342357c into openzfs:master Oct 6, 2023
19 checks passed
behlendorf pushed a commit to behlendorf/zfs that referenced this pull request Oct 6, 2023
@amotin @behlendorf
Reduce number of metaslab preload taskq threads.
d9881c0 
Before this change ZFS created threads for 50% of CPUs for each top-
level vdev.  Plus it created the same number of threads for embedded
log groups (that have only one metaslab and don't need any preload).
As result, on system with 80 CPUs and pool of 60 vdevs this resulted
in 4800 metaslab preload threads, that is absolutely insane.

This patch changes the preload threads to 50% of CPUs in one taskq
per pool, so on the mentioned system it will be only 40 threads.

Among other things this fixes zdb on the mentioned system and pool
on FreeBSD, that failed to create so many threads in one process.

Brian Behlendorf <[email protected]>
Signed-off-by:	Alexander Motin <[email protected]>
Sponsored by:	iXsystems, Inc.
Closes openzfs#15319
behlendorf pushed a commit that referenced this pull request Oct 7, 2023
@amotin @behlendorf
Reduce number of metaslab preload taskq threads.
bcd010d 
Before this change ZFS created threads for 50% of CPUs for each top-
level vdev.  Plus it created the same number of threads for embedded
log groups (that have only one metaslab and don't need any preload).
As result, on system with 80 CPUs and pool of 60 vdevs this resulted
in 4800 metaslab preload threads, that is absolutely insane.

This patch changes the preload threads to 50% of CPUs in one taskq
per pool, so on the mentioned system it will be only 40 threads.

Among other things this fixes zdb on the mentioned system and pool
on FreeBSD, that failed to create so many threads in one process.

Brian Behlendorf <[email protected]>
Signed-off-by:	Alexander Motin <[email protected]>
Sponsored by:	iXsystems, Inc.
Closes #15319
lundman pushed a commit to openzfsonwindows/openzfs that referenced this pull request Dec 12, 2023
@amotin @lundman
Reduce number of metaslab preload taskq threads.
f665db2 
Before this change ZFS created threads for 50% of CPUs for each top-
level vdev.  Plus it created the same number of threads for embedded
log groups (that have only one metaslab and don't need any preload).
As result, on system with 80 CPUs and pool of 60 vdevs this resulted
in 4800 metaslab preload threads, that is absolutely insane.

This patch changes the preload threads to 50% of CPUs in one taskq
per pool, so on the mentioned system it will be only 40 threads.

Among other things this fixes zdb on the mentioned system and pool
on FreeBSD, that failed to create so many threads in one process.

Brian Behlendorf <[email protected]>
Signed-off-by:	Alexander Motin <[email protected]>
Sponsored by:	iXsystems, Inc.
Closes openzfs#15319
@amotin amotin deleted the metaslab branch March 22, 2024 17:01
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@behlendorf behlendorf behlendorf approved these changes

@grwilson grwilson Awaiting requested review from grwilson

@prakashsurya prakashsurya Awaiting requested review from prakashsurya

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@amotin @behlendorf