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Bug #51735

open

[pwl] IO hang when the size of an IO exceeds the size of the cache

Added by CONGMIN YIN almost 3 years ago. Updated almost 3 years ago.

Status:
New
Priority:
Normal
Assignee:
Target version:
-
% Done:

0%

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

Description

IO hang when the size of an IO exceeds the size of the cache.
Root cause:

AbstractWriteLog<I>::check_allocation(){
  if (m_bytes_allocated + bytes_allocated > m_bytes_allocated_cap) {}
}

This check will set alloc false, and never pass this check.
Expected behavior: when the IO size exceeds the cache size, it bypasses the cache and writes directly to OSD.

Actions #1

Updated by CONGMIN YIN almost 3 years ago

  • Subject changed from [pwl ssd] IO hang when the size of an IO exceeds the size of the cache to [pwl] IO hang when the size of an IO exceeds the size of the cache
Actions #2

Updated by Ilya Dryomov almost 3 years ago

Do you mean the size of a single I/O request?

Actions #3

Updated by CONGMIN YIN almost 3 years ago

Ilya Dryomov wrote:

Do you mean the size of a single I/O request?

Yes

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