Re-embed multilist_t storage. #12158
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ahrens
approved these changes
May 30, 2021
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@amotin when you get a chance would you mind rebasing this on master. We've pulled in a couple FreeBSD change which should let us get a clean CI run on FreeBSD bots. |
behlendorf
approved these changes
Jun 4, 2021
Before "7968 multi-threaded spa_sync()" commit multilists were stored in caller's memory same as regular lists. It is not clear why it was changed, considering that the structure is still public, but I found it reduced performance by additional uncached pointer dereference. This commit partially reverts the mentioned one and adds some cache line alignments to separate read-only multilists and heavily modified refcount's to different cache lines. Signed-off-by: Alexander Motin <[email protected]> Sponsored-By: iXsystems, Inc.
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Jun 10, 2021
This commit partially reverts changes to multilists in PR 7968 (multi-threaded spa-sync()) and adds some cache line alignments to separate read-only multilists and heavily modified refcount's to different cache lines. Reviewed-by: Matthew Ahrens <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Alexander Motin <[email protected]> Sponsored-by: iXsystems, Inc. Closes openzfs#12158
behlendorf
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Jun 10, 2021
This commit partially reverts changes to multilists in PR 7968 (multi-threaded spa-sync()) and adds some cache line alignments to separate read-only multilists and heavily modified refcount's to different cache lines. Reviewed-by: Matthew Ahrens <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Alexander Motin <[email protected]> Sponsored-by: iXsystems, Inc. Closes openzfs#12158
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Before "7968 multi-threaded spa_sync()" commit multilists were stored
in caller's memory same as regular lists. It is not clear why it was
changed, considering that the structure is still public, but I found
it reduced performance by additional uncached pointer dereference.
This commit partially reverts the mentioned one and adds some cache
line alignments to separate read-only multilists and heavily modified
refcount's to different cache lines.
How Has This Been Tested?
On 40-thread FreeBSD system heavy uncached 4KB reads from 8 ZVOLs show ~2% IOPS increase, while profiler shows reduction of time spent in dbuf_evict_one() and descendants from 8.2% to 6.8%.
Types of changes
Checklist:
Signed-off-by.