Bug 672113 - CPU scheduler load balancer is broken
Summary: CPU scheduler load balancer is broken
Keywords:
Status: CLOSED UPSTREAM
Alias: None
Product: Red Hat Enterprise Linux 6
Classification: Red Hat
Component: kernel
Version: 6.1
Hardware: All
OS: Linux
unspecified
unspecified
Target Milestone: rc
: ---
Assignee: Rik van Riel
QA Contact: Red Hat Kernel QE team
URL:
Whiteboard: developer-cond-nack-6.3
Depends On:
Blocks: 679905 767187
TreeView+ depends on / blocked
 
Reported: 2011-01-24 00:25 UTC by Rik van Riel
Modified: 2013-01-09 23:30 UTC (History)
9 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
: 679905 (view as bug list)
Environment:
Last Closed: 2011-12-12 17:36:50 UTC
Target Upstream Version:

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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.
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