Skip to content

DDT: Add/use zap_lookup_length_uint64_by_dnode() - #18048

Merged
behlendorf merged 1 commit into
openzfs:masterfrom
amotin:zap_lookup_length
Dec 15, 2025
Merged

DDT: Add/use zap_lookup_length_uint64_by_dnode()#18048
behlendorf merged 1 commit into
openzfs:masterfrom
amotin:zap_lookup_length

Conversation

@amotin

@amotin amotin commented Dec 12, 2025 •
edited
Loading

Copy link
Copy Markdown
Member

Unlike other ZAP consumers, due to compression DDT does not know precisely how big entry it is reading from ZAP, even though knows the upper limit. Due to this it called zap_length_uint64_by_dnode() and zap_lookup_uint64_by_dnode(), each of which does full ZAP entry lookup.

Introduction of the combined ZAP method dramatically reduces the CPU overhead and locks contention at DBUF layer.

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)
  • Quality assurance (non-breaking change which makes the code more robust against bugs)
  • 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 the Status: Code Review Needed Ready for review and testing label Dec 12, 2025
behlendorf
behlendorf reviewed Dec 15, 2025
View reviewed changes
Comment thread module/zfs/ddt_zap.c Resolved
@amotin
DDT: Add/use zap_lookup_length_uint64_by_dnode()
899f30d 
Unlike other ZAP consumers due to compression DDT does not know
how big entry it is reading from ZAP.  Due to this it called
zap_length_uint64_by_dnode() and zap_lookup_uint64_by_dnode(),
each of which does full ZAP entry lookup.

Introduction of the combined ZAP method dramatically reduces the
CPU overhead and locks contention at DBUF layer.

Signed-off-by: Alexander Motin <alexander.motin@TrueNAS.com>
@behlendorf behlendorf added Status: Accepted Ready to integrate (reviewed, tested) and removed Status: Code Review Needed Ready for review and testing labels Dec 15, 2025
@behlendorf
behlendorf merged commit 3b1ff81 into openzfs:master Dec 15, 2025
24 of 26 checks passed
@amotin
amotin deleted the zap_lookup_length branch December 15, 2025 22:42
kithrup pushed a commit to KlaraSystems/zfs that referenced this pull request Dec 17, 2025
@amotin @kithrup
DDT: Add/use zap_lookup_length_uint64_by_dnode()
0668b59 
Unlike other ZAP consumers due to compression DDT does not know
how big entry it is reading from ZAP.  Due to this it called
zap_length_uint64_by_dnode() and zap_lookup_uint64_by_dnode(),
each of which does full ZAP entry lookup.

Introduction of the combined ZAP method dramatically reduces the
CPU overhead and locks contention at DBUF layer.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Alexander Motin <alexander.motin@TrueNAS.com>
Closes openzfs#18048
amotin added a commit to amotin/zfs that referenced this pull request Jan 29, 2026
@amotin
DDT: Add/use zap_lookup_length_uint64_by_dnode()
5261cd3 
Unlike other ZAP consumers due to compression DDT does not know
how big entry it is reading from ZAP.  Due to this it called
zap_length_uint64_by_dnode() and zap_lookup_uint64_by_dnode(),
each of which does full ZAP entry lookup.

Introduction of the combined ZAP method dramatically reduces the
CPU overhead and locks contention at DBUF layer.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Alexander Motin <alexander.motin@TrueNAS.com>
Closes openzfs#18048
amotin added a commit to amotin/zfs that referenced this pull request Feb 3, 2026
@amotin
DDT: Add/use zap_lookup_length_uint64_by_dnode()
2d6b0c4 
Unlike other ZAP consumers due to compression DDT does not know
how big entry it is reading from ZAP.  Due to this it called
zap_length_uint64_by_dnode() and zap_lookup_uint64_by_dnode(),
each of which does full ZAP entry lookup.

Introduction of the combined ZAP method dramatically reduces the
CPU overhead and locks contention at DBUF layer.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Alexander Motin <alexander.motin@TrueNAS.com>
Closes openzfs#18048
lundman pushed a commit to openzfsonosx/openzfs-fork that referenced this pull request Feb 5, 2026
@amotin @lundman
DDT: Add/use zap_lookup_length_uint64_by_dnode()
5d790c2 
Unlike other ZAP consumers due to compression DDT does not know
how big entry it is reading from ZAP.  Due to this it called
zap_length_uint64_by_dnode() and zap_lookup_uint64_by_dnode(),
each of which does full ZAP entry lookup.

Introduction of the combined ZAP method dramatically reduces the
CPU overhead and locks contention at DBUF layer.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Alexander Motin <alexander.motin@TrueNAS.com>
Closes openzfs#18048
tonyhutter pushed a commit that referenced this pull request Feb 5, 2026
@amotin @tonyhutter
DDT: Add/use zap_lookup_length_uint64_by_dnode()
4ab2027 
Unlike other ZAP consumers due to compression DDT does not know
how big entry it is reading from ZAP.  Due to this it called
zap_length_uint64_by_dnode() and zap_lookup_uint64_by_dnode(),
each of which does full ZAP entry lookup.

Introduction of the combined ZAP method dramatically reduces the
CPU overhead and locks contention at DBUF layer.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Alexander Motin <alexander.motin@TrueNAS.com>
Closes #18048
lundman pushed a commit to openzfsonwindows/openzfs that referenced this pull request Feb 23, 2026
@amotin @lundman
DDT: Add/use zap_lookup_length_uint64_by_dnode()
e1eaf68 
Unlike other ZAP consumers due to compression DDT does not know
how big entry it is reading from ZAP.  Due to this it called
zap_length_uint64_by_dnode() and zap_lookup_uint64_by_dnode(),
each of which does full ZAP entry lookup.

Introduction of the combined ZAP method dramatically reduces the
CPU overhead and locks contention at DBUF layer.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Alexander Motin <alexander.motin@TrueNAS.com>
Closes openzfs#18048
lundman pushed a commit to openzfsonwindows/openzfs that referenced this pull request Feb 23, 2026
@amotin @lundman
DDT: Add/use zap_lookup_length_uint64_by_dnode()
9de25aa 
Unlike other ZAP consumers due to compression DDT does not know
how big entry it is reading from ZAP.  Due to this it called
zap_length_uint64_by_dnode() and zap_lookup_uint64_by_dnode(),
each of which does full ZAP entry lookup.

Introduction of the combined ZAP method dramatically reduces the
CPU overhead and locks contention at DBUF layer.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Alexander Motin <alexander.motin@TrueNAS.com>
Closes openzfs#18048
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

@behlendorf behlendorf behlendorf approved these changes

Assignees

No one assigned

Labels

Status: Accepted Ready to integrate (reviewed, tested)

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

2 participants

@amotin @behlendorf