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Bug #53952

mds: mds_oft_prefetch_dirfrags default to false

Added by Dan van der Ster about 1 year ago. Updated 6 months ago.

Status:
Resolved
Priority:
Normal
Category:
-
Target version:
-
% Done:

0%

Source:
Tags:
Backport:
octopus,pacific,quincy
Regression:
No
Severity:
3 - minor
Reviewed:
Affected Versions:
ceph-qa-suite:
Component(FS):
MDS
Labels (FS):
Pull request ID:
Crash signature (v1):
Crash signature (v2):

Description

The oft dirfrag prefetch is unpredictable and dangerous because it can
delay rejoin by several minutes and balloon memory usage well beyond the
mds_cache_memory_limit. In the worst cases this can cause an OOM loop if
the memory required for prefetch exceeds the physical memory.

The PR which introduced mds_oft_prefetch_dirfrags also optimized the
client behaviour to eliminate the bad effects of disabling dirfrags
prefetch. And commit d3946e3 has been
testing setting this option to false.

We therefore should default the option to false. Operators can still
manually enable it if they know it can speedup their use-cases.

Related-to: https://tracker.ceph.com/issues/45835


Related issues

Copied to CephFS - Backport #54194: pacific: mds: mds_oft_prefetch_dirfrags default to false Resolved
Copied to CephFS - Backport #54195: octopus: mds: mds_oft_prefetch_dirfrags default to false Resolved
Copied to CephFS - Backport #54196: quincy: mds: mds_oft_prefetch_dirfrags default to false Resolved

History

#1 Updated by Dan van der Ster about 1 year ago

  • Pull request ID set to 44667

#2 Updated by Dan van der Ster about 1 year ago

  • Status changed from New to Fix Under Review

#3 Updated by Venky Shankar about 1 year ago

  • Backport changed from octopus,pacific to octopus,pacific,quincy

#4 Updated by Venky Shankar 12 months ago

  • Status changed from Fix Under Review to Pending Backport

#5 Updated by Backport Bot 12 months ago

  • Copied to Backport #54194: pacific: mds: mds_oft_prefetch_dirfrags default to false added

#6 Updated by Backport Bot 12 months ago

  • Copied to Backport #54195: octopus: mds: mds_oft_prefetch_dirfrags default to false added

#7 Updated by Backport Bot 12 months ago

  • Copied to Backport #54196: quincy: mds: mds_oft_prefetch_dirfrags default to false added

#8 Updated by Backport Bot 6 months ago

  • Tags set to backport_processed

#9 Updated by Konstantin Shalygin 6 months ago

  • Tracker changed from Fix to Bug
  • Status changed from Pending Backport to Resolved
  • Tags deleted (backport_processed)
  • Regression set to No
  • Severity set to 3 - minor

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