Bug 163397

Summary:	cpuspeed doesn't handle hyperthreaded cpu's effectively
Product:	Red Hat Enterprise Linux 4	Reporter:	Eric Jones <enjones>
Component:	kernel-utils	Assignee:	Jarod Wilson <jarod>
Status:	CLOSED INSUFFICIENT_DATA	QA Contact:	Brian Brock <bbrock>
Severity:	medium	Docs Contact:
Priority:	medium
Version:	4.0	CC:	fche, mk
Target Milestone:	---
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2007-06-04 21:37:19 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:

Description Eric Jones 2005-07-15 20:17:53 UTC

From Bugzilla Helper:
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Description of problem:
When using a HyperThreaded Pentium 4 CPU, the cpuspeed daemon doens't use an effective algorithm for determining the current CPU utilizization.  Since a single CPU intensive process only runs on one "virtual" CPU, the other CPU appears 100% idle, giving a net system usage of 50%.  cpuspeed sees this and lowers the clock speed, slowing down the otherwise CPU intensive application.  When running on a hyperthreaded system, cpuspeed should use the most active "virtual" processor as its gauge for current system activity.

Version-Release number of selected component (if applicable):
kernel-utils-2.4-13.1.48

How reproducible:
Always

Steps to Reproduce:
1. start cpuspeed
2. run an intense cpu benchmark on one "virtual" processor
3. cat /proc/cpuinfo and watch the processor get slowed to its lowest state (2.8 GHz on my 3.6 GHz box)
  

Actual Results:  The cpu was frequency scaled down to its lowest state.

Expected Results:  The cpu should have run at the maximum clock speed since the benchmark was utilizing 100% of one of the "virtual" processors.

Additional info:

Comment 1 Jarod Wilson 2007-01-24 14:53:32 UTC

Is this still an issue with the latest RHEL4 kernel and kernel-utils packages?
I'm taking over all cpu frequency scaling bugs, and trying to work my way
through them...

Comment 2 Jarod Wilson 2007-06-04 21:37:19 UTC

4+ months of no activity, 1.5+ years since hearing from the original poster,
closing out bug.