RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.

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.

Created attachment 475470 [details]
backport of commit 3ee48b6af49cf534ca2f481ecc484b156a41451d

upstream commit 3ee48b6af49cf534ca2f481ecc484b156a41451d adjusted to apply to 2.6.32-89.el6

ack, looks reasonable, thanks!

Patch(es) available on kernel-2.6.32-121.el6

    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.

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