Bug 588219 - 25% performance regression of concurrent O_DIRECT writes. [rhel-5.5.z]
Summary: 25% performance regression of concurrent O_DIRECT writes. [rhel-5.5.z]
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 5
Classification: Red Hat
Component: kernel
Version: 5.5
Hardware: All
OS: Linux
high
high
Target Milestone: rc
: ---
Assignee: Jiri Pirko
QA Contact: Red Hat Kernel QE team
URL:
Whiteboard:
Depends On: 574285
Blocks:
TreeView+ depends on / blocked
 
Reported: 2010-05-03 07:23 UTC by RHEL Program Management
Modified: 2015-05-05 01:19 UTC (History)
15 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
When two or more writes which used the O_DIRECT file access interface were run simultaneously on two separate partitions on the same disk, performance of both writes were reduced. This could have caused a write slowdown of approximately 25% when running two simultaneous "dd oflag=direct" commands on two different partitions. This regression has been fixed in this update so that O_DIRECT write performance does not incur a performance penalty.
Clone Of:
Environment:
Last Closed: 2010-07-01 18:29:24 UTC
Target Upstream Version:

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System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2010:0504 0 normal SHIPPED_LIVE Important: kernel security and bug fix update 2010-07-01 18:26:58 UTC

Description RHEL Program Management 2010-05-03 07:23:18 UTC 
This bug has been copied from bug #574285 and has been proposed
to be backported to 5.5 z-stream (EUS).
Comment 3 Jiri Pirko 2010-05-13 15:06:13 UTC 
in 2.6.18-194.4.1.el5
Comment 7 Douglas Silas 2010-06-28 20:15:37 UTC 
Technical note added. If any revisions are required, please edit the "Technical Notes" field
accordingly. All revisions will be proofread by the Engineering Content Services team.

New Contents:
When two or more writes which used the O_DIRECT file access interface were run simultaneously on two separate partitions on the same disk, performance of both writes were reduced. This could have caused a write slowdown of approximately 25% when running two simultaneous "dd oflag=direct" commands on two different partitions. This regression has been fixed in this update so that O_DIRECT write performance does not incur a performance penalty.
Comment 9 errata-xmlrpc 2010-07-01 18:29:24 UTC 
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHSA-2010-0504.html
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