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Bug #24909

closed

RBD client IOPS pool stats are incorrect (2x higher; includes IO hints as an op)

Added by Jason Dillaman almost 6 years ago. Updated over 5 years ago.

Status:
Resolved
Priority:
Normal
Assignee:
Jason Dillaman
Category:
-
Target version:
-
% Done:

0%

Source:
Tags:
Backport:
mimic,luminous
Regression:
No
Severity:
3 - minor
Reviewed:
Affected Versions:
ceph-qa-suite:
Component(RADOS):
Pull request ID:
Crash signature (v1):
Crash signature (v2):

Description

While running performance testing with Ceph metrics gathering statistics on the cluster, I noticed that while my RBD workload was generating ~7,000 writes/second to the cluster, Ceph metrics was showing my client is writing ~14,000 writes/second. Since these stats are just extracted from the PG stats, I looked into how those are calculated and it appears that "CEPH_OSD_OP_SETALLOCHINT" counts as a write op in terms of stat generation. Since RBD will send an alloc hint w/ each write op, it results in effectively double the write ops/second reported.


Related issues 2 (0 open2 closed)

Copied to RADOS - Backport #36556: luminous: RBD client IOPS pool stats are incorrect (2x higher; includes IO hints as an op)ResolvedNathan CutlerActions
Copied to RADOS - Backport #36557: mimic: RBD client IOPS pool stats are incorrect (2x higher; includes IO hints as an op)ResolvedNathan CutlerActions
Actions #1

Updated by Jason Dillaman almost 6 years ago

  • Status changed from New to In Progress
  • Assignee set to Jason Dillaman
Actions #2

Updated by Jason Dillaman almost 6 years ago

  • Status changed from In Progress to Fix Under Review
Actions #3

Updated by Greg Farnum almost 6 years ago

  • Subject changed from RBD client IOPS pool stats are incorrect (2x higher) to RBD client IOPS pool stats are incorrect (2x higher; includes IO hints as an op)
Actions #4

Updated by Yuri Weinstein almost 6 years ago

Jason Dillaman wrote:

https://github.com/ceph/ceph/pull/23029

merged

Actions #5

Updated by Jason Dillaman over 5 years ago

  • Status changed from Fix Under Review to Pending Backport
Actions #6

Updated by Nathan Cutler over 5 years ago

  • Copied to Backport #36556: luminous: RBD client IOPS pool stats are incorrect (2x higher; includes IO hints as an op) added
Actions #7

Updated by Nathan Cutler over 5 years ago

  • Copied to Backport #36557: mimic: RBD client IOPS pool stats are incorrect (2x higher; includes IO hints as an op) added
Actions #8

Updated by Nathan Cutler over 5 years ago

  • Status changed from Pending Backport to Resolved
Actions

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