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Bug 672113

Summary:	CPU scheduler load balancer is broken
Product:	Red Hat Enterprise Linux 6	Reporter:	Rik van Riel <riel>
Component:	kernel	Assignee:	Rik van Riel <riel>
Status:	CLOSED UPSTREAM	QA Contact:	Red Hat Kernel QE team <kernel-qe>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	6.1	CC:	akong, bburns, ilmis, jyang, lwang, lwoodman, perfbz, tburke, vgoyal
Target Milestone:	rc
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:	developer-cond-nack-6.3
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:
Clones:	679905 (view as bug list)		Environment:
Last Closed:	2011-12-12 17:36:50 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:	679905, 767187

Description Rik van Riel 2011-01-24 00:25:56 UTC

Description of problem:

The CPU scheduler's load balancer in RHEL 6 is broken. With my PLE test, it was common for 1 4-CPU virtual machine to get around 300% CPU time, while the other 4-CPU virtual machine (contending for the same 4 CPUs) only got about 100% CPU time.

Upstream has several patches to fix load balancing.  I would like to try backporting those to RHEL 6 to see if that resolves the issues observed.

Note that CPU load balancing with cgroups will probably still be broken, even with those changesets applied; that is another bug alltogether.