Bug 575897

Summary:	CONFIG_MULTICORE_RAID456 causes excessive cpu load
Product:	[Fedora] Fedora	Reporter:	Dan Williams <dan.j.williams>
Component:	kernel	Assignee:	Kernel Maintainer List <kernel-maint>
Status:	CLOSED DUPLICATE	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	medium	Docs Contact:
Priority:	low
Version:	12	CC:	anton, dougsland, gansalmon, itamar, jonathan, kernel-maint, rmj
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:	2010-04-07 05:17:43 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 Dan Williams 2010-03-22 16:33:26 UTC

Description of problem:
CONFIG_RAID456_MULTICORE is an experimental feature targeted at developers looking to experiment with parallel processing in md raid.  In some situations it show benefits but in other this option causes excessive cpu load and throughput reduction, it is not ready for production systems.

Version-Release number of selected component (if applicable):
kernel-2.6.32.9-70.fc12 (probably all 2.6.32 fc12 releases)


How reproducible:
Always

Steps to Reproduce:
Issue write traffic to the array.
  
Actual results:
async subsytem launches and excessive number of threads


Expected results:
Normal cpu utilization characteristics of the single-threaded raid5d case.


Additional info:
http://marc.info/?l=linux-raid&m=125909551116881&w=2

Comment 1 Dan Williams 2010-03-24 14:27:58 UTC

Correction, the name of the option is CONFIG_MULTICORE_RAID456.

Comment 2 Chuck Ebbert 2010-04-07 05:17:43 UTC


*** This bug has been marked as a duplicate of bug 575402 ***