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Bug 454270

Summary: SCHED_FIFO spec violation
Product: Red Hat Enterprise MRG Reporter: IBM Bug Proxy <bugproxy>
Component: realtime-kernelAssignee: Peter Zijlstra <pzijlstr>
Status: CLOSED ERRATA QA Contact:
Severity: high Docs Contact:
Priority: low    
Version: betaCC: bhu, davids, lwang, williams
Target Milestone: 1.0.3   
Target Release: ---   
Hardware: All   
OS: All   
Whiteboard:
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2008-10-07 19:21:34 UTC Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Attachments:
Description Flags
[PATCH] Enqueue deprioritized RT tasks to head of prio array none

Description IBM Bug Proxy 2008-07-07 12:08:21 UTC
=Comment: #0=================================================
Darren V. Hart <dvhltc@us.ibm.com> - 2008-07-03 13:10 EDT
According to the SUS, when a SCHED_FIFO task's priority is lowered, it should be
added to the head of the corresponding priority array:

http://www.opengroup.org/onlinepubs/009695399/functions/xsh_chap02_08.html#tag_02_08_04_01

Peter Z. noticed this and wrote a patch to address it:

http://lkml.org/lkml/2008/6/16/344

The dequeue_rt_stack() apparently still needs some work according to peterz
comments.

=Comment: #2=================================================
Darren V. Hart <dvhltc@us.ibm.com> - 2008-07-03 13:22 EDT
The enqueue_task changed in 2.6.25, so a backport will be required.  It's a
simple patch, so that shouldn't pose a problem.

=Comment: #3=================================================
Darren V. Hart <dvhltc@us.ibm.com> - 2008-07-03 15:01 EDT
I've backported the patch and have an R2 patch ready.  Currently under test on
elm3b172 running release-testing.sh.
=Comment: #4=================================================
Darren V. Hart <dvhltc@us.ibm.com> - 2008-07-03 18:27 EDT

[PATCH] Enqueue deprioritized RT tasks to head of prio array

The attached patch is currently undergoing release-testing.

Comment 1 IBM Bug Proxy 2008-07-07 12:08:24 UTC
Created attachment 311140 [details]
[PATCH] Enqueue deprioritized RT tasks to head of prio array

Comment 2 Clark Williams 2008-08-20 13:46:33 UTC
Are we good with this one?

Comment 3 IBM Bug Proxy 2008-08-20 17:00:53 UTC
(In reply to comment #11)
> ------- Comment From williams@redhat.com 2008-08-20 09:46:33 EDT-------
> Are we good with this one?

Yup.

Comment 5 David Sommerseth 2008-10-06 16:38:27 UTC
Verified by code review

Comment 7 errata-xmlrpc 2008-10-07 19:21:34 UTC
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-2008-0857.html