588219 – 25% performance regression of concurrent O_DIRECT writes. [rhel-5.5.z]

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]

Status:	CLOSED ERRATA
Alias:	None
Product:	Red Hat Enterprise Linux 5
Classification:	Red Hat
Component:	kernel
Sub Component:
Version:	5.5
Hardware:	All
OS:	Linux
Priority:	high
Severity:	high
Target Milestone:	rc
Target Release:	---
Assignee:	Jiri Pirko
QA Contact:	Red Hat Kernel QE team
Docs Contact:
URL:
Whiteboard:
Keywords:	Reopened, ZStream
Depends On:	574285
Blocks:
TreeView+	depends on / blocked

Reported:	2010-05-03 07:23 UTC by RHEL Product and Program Management
Modified:	2015-05-05 01:19 UTC (History)
CC List:	15 users (show)
Fixed In Version:
Doc Type:
Doc Text:	(edit) 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. 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:	(edit)
Last Closed:	2010-07-01 18:29:24 UTC
Dependent Products:

Attachments	(Terms of Use)
Add an attachment (proposed patch, testcase, etc.)

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

Description RHEL Product and 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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