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Do not request data L1 buffers on scan prefetch. #15029

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merged 1 commit into from
Jul 20, 2023

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@amotin amotin commented Jul 3, 2023

Set ARC_FLAG_NO_BUF when prefetching data L1 buffers for scan. We do not prefetch data L0 buffers, so we do not need the L1 buffers, only want them to be ready in ARC. This saves some CPU time on the buffers decompression.

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:

Set ARC_FLAG_NO_BUF when prefetching data L1 buffers for scan.  We
do not prefetch data L0 buffers, so we do not need the L1 buffers,
only want them to be ready in ARC. This saves some CPU time on the
buffers decompression.

Signed-off-by:	Alexander Motin <[email protected]>
Sponsored by:	iXsystems, Inc.
@amotin amotin changed the title Do not get ask for data L1 buffers on scan prefetch. Do not request data L1 buffers on scan prefetch. Jul 3, 2023
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amotin commented Jul 3, 2023

@tcaputi Could you take a look please.

@amotin amotin added the Status: Code Review Needed Ready for review and testing label Jul 3, 2023
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tcaputi commented Jul 5, 2023

I'm sorry, but I am probably not the best person to review this anymore. I haven't actively worked on ZFS in a few years now. This is a small change, and looks good on its own, but its hard for me (at this point) to think about what other ramifications this might have after being away from the ZFS code base for so long.

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This looks reasonable to me.

@behlendorf behlendorf added Status: Accepted Ready to integrate (reviewed, tested) and removed Status: Code Review Needed Ready for review and testing labels Jul 14, 2023
@behlendorf behlendorf merged commit 7d0df54 into openzfs:master Jul 20, 2023
behlendorf pushed a commit to behlendorf/zfs that referenced this pull request Jul 21, 2023
Set ARC_FLAG_NO_BUF when prefetching data L1 buffers for scan.  We
do not prefetch data L0 buffers, so we do not need the L1 buffers,
only want them to be ready in ARC. This saves some CPU time on the
buffers decompression.

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by:	Alexander Motin <[email protected]>
Sponsored by:	iXsystems, Inc.
Closes openzfs#15029
behlendorf pushed a commit that referenced this pull request Jul 21, 2023
Set ARC_FLAG_NO_BUF when prefetching data L1 buffers for scan.  We
do not prefetch data L0 buffers, so we do not need the L1 buffers,
only want them to be ready in ARC. This saves some CPU time on the
buffers decompression.

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by:	Alexander Motin <[email protected]>
Sponsored by:	iXsystems, Inc.
Closes #15029
lundman pushed a commit to openzfsonwindows/openzfs that referenced this pull request Dec 12, 2023
Set ARC_FLAG_NO_BUF when prefetching data L1 buffers for scan.  We
do not prefetch data L0 buffers, so we do not need the L1 buffers,
only want them to be ready in ARC. This saves some CPU time on the
buffers decompression.

Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by:	Alexander Motin <[email protected]>
Sponsored by:	iXsystems, Inc.
Closes openzfs#15029
@amotin amotin deleted the no_l1_pref branch March 22, 2024 16:34
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3 participants