Bug 672937

Summary: backport set_iounmap_nonlazy() to speedup reading of /proc/vmcore
Product: Red Hat Enterprise Linux 6 Reporter: Dave Maley <dmaley>
Component: kernelAssignee: Neil Horman <nhorman>
Status: CLOSED ERRATA QA Contact: chen yuwen <yuchen>
Severity: urgent Docs Contact:
Priority: urgent    
Version: 6.1CC: dhoward, fhrbata, jeder, jwest, phan, qcai, satbfydwno
Target Milestone: rcKeywords: ZStream
Target Release: ---   
Hardware: Unspecified   
OS: Unspecified   
Whiteboard:
Fixed In Version: kernel-2.6.32-121.el6 Doc Type: Bug Fix
Doc Text:
Reading the /proc/vmcore file was previously significantly slower on a Red Hat Enterprise Linux 6 system when compared to a Red Hat Enterprise Linux 5 system. This update enables caching of memory accesses; reading of the /proc/vmcore file is now noticeably faster.
 Story Points: ---
Clone Of: Environment:
Last Closed: 2011-05-19 12:50:00 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: 683442    
Attachments:
Description Flags
backport of commit 3ee48b6af49cf534ca2f481ecc484b156a41451d none

Description Dave Maley 2011-01-26 18:28:38 UTC 
Description of problem:
Reading /proc/vmcore is significantly slower on RHEL6 compared to RHEL5.  The patch from bug 641315 helps to improve things however another patch has been committed upstream which further helps boost performance closer to that of RHEL5.

http://git.kernel.org/?p=linux/kernel/git/x86/linux-2.6-tip.git;a=commitdiff;h=3ee48b6af49cf534ca2f481ecc484b156a41451d


Version-Release number of selected component (if applicable):
kernel-2.6.32-71.e16
kernel-2.6.32-89.el6 (includes patch from bug 641315)


How reproducible:
Always


Steps to Reproduce:
1. configure kdump
2. crash system
3. time duration


Actual results:
A RHEL6 system w/ 8GB ram takes 4 minutes 16 seconds.  On the same system RHEL5.5 is less than 20 seconds.  The patch from bug 641315 improves it to 2 minutes 32 seconds.


Expected results:
Performance similar to RHEL5.5.


Additional info:
Business impact: This issue will cause huge increase in service down time on a server with large memory on RHEL6.
Comment 1 Dave Maley 2011-01-26 19:30:38 UTC 
Created attachment 475470 [details]
backport of commit 3ee48b6af49cf534ca2f481ecc484b156a41451d

upstream commit 3ee48b6af49cf534ca2f481ecc484b156a41451d adjusted to apply to 2.6.32-89.el6
Comment 7 Neil Horman 2011-02-18 19:02:30 UTC 
ack, looks reasonable, thanks!
Comment 9 Aristeu Rozanski 2011-03-10 17:57:46 UTC 
Patch(es) available on kernel-2.6.32-121.el6
Comment 13 Martin Prpič 2011-04-12 12:43:24 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 was previously significantly slower on a Red Hat Enterprise Linux 6 system when compared to a Red Hat Enterprise Linux 5 system. This update enables caching of memory accesses; reading of the /proc/vmcore file is now noticeably faster.
Comment 15 errata-xmlrpc 2011-05-19 12:50:00 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