Bug 647434 – perf: Mark software events as irqsafe

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Bug 647434 - perf: Mark software events as irqsafe

Summary:	perf: Mark software events as irqsafe

Status:	CLOSED ERRATA

Aliases:	None

Product:	Red Hat Enterprise MRG
Classification:	Red Hat
Component:	realtime-kernel (Show other bugs)
Sub Component:
Version:	1.3
Hardware:	Unspecified Linux

Priority	low Severity medium
Target Milestone:	---
Target Release:	---
Assigned To:	John Kacur
QA Contact:	David Sommerseth
Docs Contact:

URL:
Whiteboard:
Keywords:

Depends On:
Blocks:
	Show dependency tree / graph

Reported:	2010-10-28 07:10 EDT by John Kacur
Modified:	2016-05-22 19:31 EDT (History)
CC List:	4 users (show)

See Also:
Fixed In Version:
Doc Type:	Bug Fix
Doc Text:	* Cause: * Consequence: * Fix: * Result:
Story Points:	---
Clone Of:
Environment:
Last Closed:	2010-12-08 14:11:05 EST
Type:	---
Regression:	---
Mount Type:	---
Documentation:	---
CRM:
Verified Versions:
Category:	---
oVirt Team:	---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---

Attachments	(Terms of Use)
bz647434-perf-Mark-software-events-as-irqsafe.patch (1.22 KB, patch) 2010-10-28 07:17 EDT, John Kacur	no flags	Details \| Diff
Add an attachment (proposed patch, testcase, etc.)

External Trackers
Tracker	ID	Priority	Status	Summary	Last Updated
Red Hat Product Errata	RHSA-2010:0958	normal	SHIPPED_LIVE	Important: kernel-rt security and bug fix update	2010-12-08 14:08:55 EST

Groups: None (edit)

Description John Kacur 2010-10-28 07:10:53 EDT

From: Peter Zijlstra <peterz@infradead.org>

Noticed while using 'perf top' on a machine without a supported PMU on
2.6.33.7-rt29, when top falls back to using the "cpu-clock" software
event.

Reproduced on other machines where the problem was masked due to the
existence and use of hardware events, by explicitely asking for a
software event using:

perf top -e cpu-clock

Comment 1 John Kacur 2010-10-28 07:17:38 EDT

Created attachment 456218 [details]
bz647434-perf-Mark-software-events-as-irqsafe.patch

Comment 3 Clark Williams 2010-11-22 17:28:26 EST

    Technical note added. If any revisions are required, please edit the "Technical Notes" field
    accordingly. All revisions will be proofread by the Engineering Content Services team.
    
    New Contents:
* Cause: 
* Consequence: 
* Fix: 
* Result:

Comment 5 John Kacur 2010-11-24 15:27:04 EST

(In reply to comment #3)
>     Technical note added. If any revisions are required, please edit the
> "Technical Notes" field
>     accordingly. All revisions will be proofread by the Engineering Content
> Services team.
> 
>     New Contents:
> * Cause: 
> * Consequence: 
> * Fix: 
> * Result:

Cause: using 'perf top' on a machine without a supported PMU on
2.6.33.7-rt29, when top falls back to using the "cpu-clock" software
event.

Consequence: BUG: scheduling while atomic

Fix: Patch is attached to this bugzilla

Result: no BUG is triggered

Comment 6 David Sommerseth 2010-12-03 10:45:05 EST

Verified by code review and by running 'perf top'.

Found bz647434-perf-Mark-software-events-as-irqsafe.patch (mrg-rt-v2.git 8676f3c7afd090d5881b998e8e809d00546990e7) applied to kernel-rt-2.6.33.7-rt29.47.src.rpm.

When running 'perf top' on athlon4.rhts.eng.bos.redhat.com with -rt29.45 the box froze completely after a short time.  When running -rt29.47 'perf top' did it's job and the box did not freeze at all.

Comment 8 errata-xmlrpc 2010-12-08 14:11:05 EST

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHSA-2010-0958.html

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