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Bug #38538

Performance improvements for object-map

Added by Jason Dillaman 6 months ago. Updated 5 months ago.

Status:
Pending Backport
Priority:
Normal
Target version:
-
Start date:
03/01/2019
Due date:
% Done:

0%

Source:
Tags:
Backport:
luminous,mimic
Regression:
No
Severity:
3 - minor
Reviewed:
Affected Versions:
ceph-qa-suite:
Pull request ID:

Description

The "object_map_update" OSD class method has a some low-hanging improvements that can be made to increase the performance of object-map updates:

1) the std::vector BitVector uses for the bitset data is zeroed before it's contents are replaced with the bitset data read from the object-map object. This is a huge unnecessary CPU hit for larger object-maps.

2) the entire footer is read into memory even though only 4 bytes might be changed for an updated CRC. For large RBD images, this could be up to 16KiB of data in the worst-case scenario.

A stress-test against librados_test_stub shows improvement from ~100 updates/sec to over 50K updates/sec. The OSD is still limited to approximately 2-3K write operations per second, so longer term refactoring of the object-map design will be required to improve it's performance by orders of magnitude.


Related issues

Copied to rbd - Backport #38673: mimic: Performance improvements for object-map In Progress
Copied to rbd - Backport #38674: luminous: Performance improvements for object-map Resolved

History

#1 Updated by Jason Dillaman 6 months ago

  • Status changed from In Progress to Need Review
  • Pull request ID set to 26721

#2 Updated by Mykola Golub 5 months ago

  • Status changed from Need Review to Pending Backport

#3 Updated by Nathan Cutler 5 months ago

  • Copied to Backport #38673: mimic: Performance improvements for object-map added

#4 Updated by Nathan Cutler 5 months ago

  • Copied to Backport #38674: luminous: Performance improvements for object-map added

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