Bug 618444

Summary: disable transparent hugepages by default on small systems
Product: Red Hat Enterprise Linux 6 Reporter: Qian Cai <qcai>
Component: kernelAssignee: Rik van Riel <riel>
Status: CLOSED CURRENTRELEASE QA Contact: Zhouping Liu <zliu>
Severity: high Docs Contact:
Priority: medium    
Version: 6.0CC: czhang, nobody+295318
Target Milestone: rc   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
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Clone Of: Environment:
Last Closed: 2010-11-11 16:09:06 UTC Type: ---
Regression: --- Mount Type: ---
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Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description Qian Cai 2010-07-26 23:04:17 UTC 
Description of problem:
From: Rik van Riel <riel>
On small systems, the extra memory used by the anti-fragmentation
memory reserve and simply because huge pages are smaller than large
pages can easily outweigh the benefits of less TLB misses.

In case of the crashdump kernel, OOMs have been observed due to
the anti-fragmentation memory reserve taking up a large fraction
of the crashdump image.

This patch disables transparent hugepages on systems with less
than 1GB of RAM, but the hugepage subsystem is fully initialized
so administrators can enable THP through /sys if desired.
Comment 2 Aristeu Rozanski 2010-07-28 17:53:01 UTC 
Patch(es) available on kernel-2.6.32-54.el6
Comment 6 releng-rhel@redhat.com 2010-11-11 16:09:06 UTC 
Red Hat Enterprise Linux 6.0 is now available and should resolve
the problem described in this bug report. This report is therefore being closed
with a resolution of CURRENTRELEASE. You may reopen this bug report if the
solution does not work for you.