Add explicit prefetches to bpobj_iterate(). #15071
Merged
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
amotin
added
Type: Performance
amotin
force-pushed
the
bpopj_pref
branch
4 times, most recently
from
e845cbc
to
2979ded
Compare
To simplify error handling bpobj_iterate_blkptrs() iterates through the list of block pointers backwards. Unfortunately speculative prefetcher is currently unable to detect such patterns, that makes each block read there synchronous and very slow on HDD pools. According to my tests, added explicit prefetch reduces time needed to asynchronously delete 8 snapshots of 4 million blocks each from 20 seconds to less than one, that should free sync thread for other useful work, such as async writes, scrub, etc. While there, plug one memory leak in case of bpobj_open() error and harmonize some variable names. Signed-off-by: Alexander Motin <[email protected]> Sponsored by: iXsystems, Inc.
allanjude
approved these changes
Jul 17, 2023
behlendorf
approved these changes
Jul 20, 2023
behlendorf
added
Status: Accepted
|
Looks good. |
behlendorf
pushed a commit
to behlendorf/zfs
that referenced
this pull request
Jul 21, 2023
To simplify error handling bpobj_iterate_blkptrs() iterates through the list of block pointers backwards. Unfortunately speculative prefetcher is currently unable to detect such patterns, that makes each block read there synchronous and very slow on HDD pools. According to my tests, added explicit prefetch reduces time needed to asynchronously delete 8 snapshots of 4 million blocks each from 20 seconds to less than one, that should free sync thread for other useful work, such as async writes, scrub, etc. While there, plug one memory leak in case of bpobj_open() error and harmonize some variable names. Reviewed-by: Allan Jude <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Alexander Motin <[email protected]> Sponsored by: iXsystems, Inc. Closes openzfs#15071
behlendorf
pushed a commit
that referenced
this pull request
Jul 21, 2023
To simplify error handling bpobj_iterate_blkptrs() iterates through the list of block pointers backwards. Unfortunately speculative prefetcher is currently unable to detect such patterns, that makes each block read there synchronous and very slow on HDD pools. According to my tests, added explicit prefetch reduces time needed to asynchronously delete 8 snapshots of 4 million blocks each from 20 seconds to less than one, that should free sync thread for other useful work, such as async writes, scrub, etc. While there, plug one memory leak in case of bpobj_open() error and harmonize some variable names. Reviewed-by: Allan Jude <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Alexander Motin <[email protected]> Sponsored by: iXsystems, Inc. Closes #15071
lundman
pushed a commit
to openzfsonwindows/openzfs
that referenced
this pull request
Dec 12, 2023
To simplify error handling bpobj_iterate_blkptrs() iterates through the list of block pointers backwards. Unfortunately speculative prefetcher is currently unable to detect such patterns, that makes each block read there synchronous and very slow on HDD pools. According to my tests, added explicit prefetch reduces time needed to asynchronously delete 8 snapshots of 4 million blocks each from 20 seconds to less than one, that should free sync thread for other useful work, such as async writes, scrub, etc. While there, plug one memory leak in case of bpobj_open() error and harmonize some variable names. Reviewed-by: Allan Jude <[email protected]> Reviewed-by: Brian Behlendorf <[email protected]> Signed-off-by: Alexander Motin <[email protected]> Sponsored by: iXsystems, Inc. Closes openzfs#15071
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
To simplify error handling bpobj_iterate_blkptrs() iterates through the list of block pointers backwards. Unfortunately speculative prefetcher is currently unable to detect such patterns, that makes each block read there synchronous and very slow on HDD pools.
According to my tests, added explicit prefetch reduces time needed to asynchronously delete 8 snapshots of 4 million blocks each from 20 seconds to less than one, that should free sync thread for other useful work, such as async writes, scrub, etc.
While there, plug one memory leak in case of bpobj_open() error and harmonize some variable names.
Types of changes
Checklist:
Signed-off-by.