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Bug 1201552

Summary:	irqbalance should not place irqs on isolated CPUs
Product:	Red Hat Enterprise Linux 7	Reporter:	Rik van Riel <riel>
Component:	irqbalance	Assignee:	Petr Holasek <pholasek>
Status:	CLOSED ERRATA	QA Contact:	Andrej Manduch <amanduch>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	7.1	CC:	amanduch, dhoward, emcnabb, hhuang, jeder, knoel, lcapitulino, lmiksik, mtosatti, nhorman, qguo, williams
Target Milestone:	rc
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	irqbalance-1.0.7-3.el7	Doc Type:	Enhancement
Doc Text:	Cause: Irqbalance assigned IRQs also to isolated CPUs which are not under control of scheduler and usually used for some special dedicated purposes (HPC) Consequence: Perfomance of tasks running on isolated CPUs could be harm. Fix: Irqbalance parses isolated CPUs from kernel commandline Result: Irqbalance doesn't assign IRQs to isolated CPUs so task running there are not interfered.	Story Points:	---
Clone Of:
Clones:	1244948 (view as bug list)		Environment:
Last Closed:	2015-11-19 05:21:34 UTC	Type:	Bug
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:	1175461, 1244948

Description Rik van Riel 2015-03-12 22:53:33 UTC

Description of problem:

irqbalance can place IRQs on isolated CPUs, as specified with isolcpus= on the kernel commandline

Steps to Reproduce:
1. boot kernel with isolcpus=N-M  (to isolate cpus N-M)
2. start irqbalance
3. watch irqs get assigned to those CPUs, anyway

Expected results:

irqbalance is smart enough to skip assigning irqs to isolated cpus

Additional info:

I submitted a pull request for patches that add this functionality into upstream irqbalance:

https://github.com/Irqbalance/irqbalance/pull/19

This functionality should help keep maximum latencies down for realtime workloads on isolated cpus.

Comment 4 errata-xmlrpc 2015-11-19 05:21:34 UTC

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHBA-2015-2207.html