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Prefetch on deadlists merge. #14402

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merged 1 commit into from
Jan 25, 2023
Merged

Prefetch on deadlists merge. #14402

merged 1 commit into from
Jan 25, 2023

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@amotin amotin commented Jan 18, 2023 •
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During snapshot deletion ZFS may issue several reads for each deadlist to merge them into next snapshot's or pool's bpobj. Number of the deadlists increases with number of snapshots. On HDD pools it may take significant time during which sync thread is blocked.

This patch introduces prescient prefetch of required blocks for up to 128 deadlists ahead. Tests show reduction of time required to delete dataset with 720 snapshots with randomly overwritten file on wide HDD pool from 75-85 to 22-28 seconds.

How Has This Been Tested?

Tested on workload generated by script in #14276 (comment) .

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 amotin added Status: Code Review Needed Ready for review and testing Type: Performance Performance improvement or performance problem labels Jan 18, 2023
@amotin amotin force-pushed the deadlist_prefetch branch 5 times, most recently from a2ba11d to 626f17a Compare January 18, 2023 16:44
@amotin amotin requested review from ahrens, behlendorf and a user January 18, 2023 17:32
allanjude
allanjude approved these changes Jan 19, 2023
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Reviewed-by: Allan Jude <[email protected]>

behlendorf
behlendorf reviewed Jan 20, 2023
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module/zfs/bpobj.c Outdated Show resolved Hide resolved
module/zfs/dsl_deadlist.c Show resolved Hide resolved
module/zfs/dsl_deadlist.c Show resolved Hide resolved
@amotin
Prefetch on deadlists merge.
6dd3bb1 
During snapshot deletion ZFS may issue several reads for each deadlist
to merge them into next snapshot's or pool's bpobj.  Number of the dead
lists increases with number of snapshots.  On HDD pools it may take
significant time during which sync thread is blocked.

This patch introduces prescient prefetch of required blocks for up to
128 deadlists ahead.  Tests show reduction of time required to delete
dataset with 720 snapshots with randomly overwritten file on wide HDD
pool from 75-85 to 22-28 seconds.

Signed-off-by:	Alexander Motin <[email protected]>
Sponsored by:	iXsystems, Inc.
@amotin amotin mentioned this pull request Jan 21, 2023
Open
@behlendorf behlendorf added Status: Accepted Ready to integrate (reviewed, tested) and removed Status: Code Review Needed Ready for review and testing labels Jan 24, 2023
@behlendorf behlendorf merged commit dc5c800 into openzfs:master Jan 25, 2023
amotin added a commit to amotin/zfs that referenced this pull request Mar 2, 2023
@amotin
Prefetch on deadlists merge
a96fc06 
During snapshot deletion ZFS may issue several reads for each deadlist
to merge them into next snapshot's or pool's bpobj.  Number of the dead
lists increases with number of snapshots.  On HDD pools it may take
significant time during which sync thread is blocked.

This patch introduces prescient prefetch of required blocks for up to
128 deadlists ahead.  Tests show reduction of time required to delete
dataset with 720 snapshots with randomly overwritten file on wide HDD
pool from 75-85 to 22-28 seconds.

Reviewed-by: Allan Jude <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by:	Alexander Motin <[email protected]>
Sponsored by:	iXsystems, Inc.
Issue openzfs#14276 
Closes openzfs#14402
amotin added a commit to amotin/zfs that referenced this pull request Mar 2, 2023
@amotin
Prefetch on deadlists merge
37dc5ac 
During snapshot deletion ZFS may issue several reads for each deadlist
to merge them into next snapshot's or pool's bpobj.  Number of the dead
lists increases with number of snapshots.  On HDD pools it may take
significant time during which sync thread is blocked.

This patch introduces prescient prefetch of required blocks for up to
128 deadlists ahead.  Tests show reduction of time required to delete
dataset with 720 snapshots with randomly overwritten file on wide HDD
pool from 75-85 to 22-28 seconds.

Reviewed-by: Allan Jude <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by:	Alexander Motin <[email protected]>
Sponsored by:	iXsystems, Inc.
Issue openzfs#14276 
Closes openzfs#14402
behlendorf pushed a commit that referenced this pull request Mar 2, 2023
@amotin @behlendorf
Prefetch on deadlists merge
b644a45 
During snapshot deletion ZFS may issue several reads for each deadlist
to merge them into next snapshot's or pool's bpobj.  Number of the dead
lists increases with number of snapshots.  On HDD pools it may take
significant time during which sync thread is blocked.

This patch introduces prescient prefetch of required blocks for up to
128 deadlists ahead.  Tests show reduction of time required to delete
dataset with 720 snapshots with randomly overwritten file on wide HDD
pool from 75-85 to 22-28 seconds.

Reviewed-by: Allan Jude <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by:	Alexander Motin <[email protected]>
Sponsored by:	iXsystems, Inc.
Issue #14276 
Closes #14402
lundman pushed a commit to openzfsonwindows/openzfs that referenced this pull request Mar 3, 2023
@amotin @lundman
Prefetch on deadlists merge
99f46ad 
During snapshot deletion ZFS may issue several reads for each deadlist
to merge them into next snapshot's or pool's bpobj.  Number of the dead
lists increases with number of snapshots.  On HDD pools it may take
significant time during which sync thread is blocked.

This patch introduces prescient prefetch of required blocks for up to
128 deadlists ahead.  Tests show reduction of time required to delete
dataset with 720 snapshots with randomly overwritten file on wide HDD
pool from 75-85 to 22-28 seconds.

Reviewed-by: Allan Jude <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by:	Alexander Motin <[email protected]>
Sponsored by:	iXsystems, Inc.
Issue openzfs#14276 
Closes openzfs#14402
rkojedzinszky pushed a commit to rkojedzinszky/zfs that referenced this pull request Mar 7, 2023
@amotin
Prefetch on deadlists merge
1f72735 
During snapshot deletion ZFS may issue several reads for each deadlist
to merge them into next snapshot's or pool's bpobj.  Number of the dead
lists increases with number of snapshots.  On HDD pools it may take
significant time during which sync thread is blocked.

This patch introduces prescient prefetch of required blocks for up to
128 deadlists ahead.  Tests show reduction of time required to delete
dataset with 720 snapshots with randomly overwritten file on wide HDD
pool from 75-85 to 22-28 seconds.

Reviewed-by: Allan Jude <[email protected]>
Reviewed-by: Brian Behlendorf <[email protected]>
Signed-off-by:	Alexander Motin <[email protected]>
Sponsored by:	iXsystems, Inc.
Issue openzfs#14276 
Closes openzfs#14402
@amotin amotin deleted the deadlist_prefetch branch October 9, 2023 13:23
behlendorf added a commit that referenced this pull request Oct 13, 2023
@behlendorf
Tag 2.2.0
9578519 
New Features
- Block cloning (#13392)
- Linux container support (#14070, #14097, #12263)
- Scrub error log (#12812, #12355)
- BLAKE3 checksums (#12918)
- Corrective "zfs receive"
- Vdev and zpool user properties

Performance
- Fully adaptive ARC (#14359)
- SHA2 checksums (#13741)
- Edon-R checksums (#13618)
- Zstd early abort (#13244)
- Prefetch improvements (#14603, #14516, #14402, #14243, #13452)
- General optimization (#14121, #14123, #14039, #13680, #13613,
  #13606, #13576, #13553, #12789, #14925, #14948)

Signed-off-by: Brian Behlendorf <[email protected]>
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@allanjude allanjude allanjude approved these changes

@behlendorf behlendorf behlendorf approved these changes

@ahrens ahrens Awaiting requested review from ahrens

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@amotin @behlendorf @allanjude