Bug 641315

Summary:	Backport upstream cacheing fix for optimizing reads from /proc/vmcore
Product:	Red Hat Enterprise Linux 6	Reporter:	Jon Masters <jcm>
Component:	kernel	Assignee:	Neil Horman <nhorman>
Status:	CLOSED ERRATA	QA Contact:	chen yuwen <yuchen>
Severity:	urgent	Docs Contact:
Priority:	urgent
Version:	6.1	CC:	dhoward, fhrbata, jcm, jwest, ltroan, lwang, nhorman, phan, qcai, tsato, tumeya
Target Milestone:	rc	Keywords:	ZStream
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	kernel-2.6.32-85.el6	Doc Type:	Bug Fix
Doc Text:	Reading the /proc/vmcore file on a Red Hat Enterprise Linux 6 system was not optimal because it did not always take advantage of reading through the cached memory. With this update, access to the /dev/oldmem device in the /proc/vmcore file is cached, resulting in faster copying to user space.	Story Points:	---
Clone Of:		Environment:
Last Closed:	2011-05-19 12:49:20 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:
Bug Blocks:	683445

Description Jon Masters 2010-10-08 11:49:48 UTC

Description of problem:

The mechanism used to read /proc/vmcore on 6.0 is not optimal because it does not always take advantage of reading through cached memory. The following upstream commit should be backported because it dramatically improves performance for at least one partner that tested on RHEL6.0:

http://lists.infradead.org/pipermail/kexec/2010-September/004498.html

Jon.

Comment 3 Linda Wang 2010-10-11 18:04:54 UTC

*** Bug 641990 has been marked as a duplicate of this bug. ***

Comment 4 Neil Horman 2010-10-13 18:51:22 UTC

http://brewweb.devel.redhat.com/brew/taskinfo?taskID=2821989
test build

Comment 7 RHEL Program Management 2010-11-19 17:20:03 UTC

This request was evaluated by Red Hat Product Management for inclusion
in a Red Hat Enterprise Linux maintenance release. Product Management has 
requested further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed 
products. This request is not yet committed for inclusion in an Update release.

Comment 9 Aristeu Rozanski 2010-12-13 15:14:48 UTC

Patch(es) available on kernel-2.6.32-89.el6

Comment 16 Martin Prpič 2011-04-12 12:44:24 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:
Reading the /proc/vmcore file on a Red Hat Enterprise Linux 6 system was not optimal because it did not always take advantage of reading through the cached memory. With this update, access to the /dev/oldmem device in the /proc/vmcore file is cached, resulting in faster copying to user space.

Comment 18 errata-xmlrpc 2011-05-19 12:49:20 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-2011-0542.html