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Bug #58000

mds: switch submit_mutex to fair mutex for MDLog

Added by Xiubo Li 3 months ago. Updated about 1 month ago.

Status:
Pending Backport
Priority:
Normal
Assignee:
Category:
Correctness/Safety
Target version:
% Done:

0%

Source:
Tags:
backport_processed
Backport:
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 implementations of the Mutex (e.g. std::mutex in C++) do not
guarantee fairness, they do not guarantee that the lock will be
acquired by threads in the order that they called the lock().

In most case this works well, but in overload case the client
requests handling thread and _submit_thread could always successfully
acquire the submit_mutex in a long time, which could make the
MDLog::trim() get stuck. That means the MDS daemons will fill journal
logs into the metadata pool, but couldn't trim the expired segments
in time.

This will switch the submit_mutex to fair mutex and it could make
sure that the all the submit_mutex waiters are in FIFO order and
could get a change to be excuted in time.


Related issues

Copied to CephFS - Backport #58343: pacific: mds: switch submit_mutex to fair mutex for MDLog In Progress
Copied to CephFS - Backport #58344: quincy: mds: switch submit_mutex to fair mutex for MDLog In Progress

History

#2 Updated by Xiubo Li 3 months ago

  • Pull request ID set to 48822

#3 Updated by Venky Shankar 2 months ago

  • Category set to Correctness/Safety
  • Status changed from New to Fix Under Review
  • Assignee set to Xiubo Li
  • Target version set to v18.0.0
  • Backport set to pacific,quincy

#4 Updated by Venky Shankar about 1 month ago

  • Status changed from Fix Under Review to Pending Backport

#5 Updated by Backport Bot about 1 month ago

  • Copied to Backport #58343: pacific: mds: switch submit_mutex to fair mutex for MDLog added

#6 Updated by Backport Bot about 1 month ago

  • Copied to Backport #58344: quincy: mds: switch submit_mutex to fair mutex for MDLog added

#7 Updated by Backport Bot about 1 month ago

  • Tags set to backport_processed

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