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Bug 711600 - backport "sched: Next buddy hint on sleep and preempt path"
Summary: backport "sched: Next buddy hint on sleep and preempt path"
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 6
Classification: Red Hat
Component: kernel
Version: 6.1
Hardware: Unspecified
OS: Unspecified
medium
medium
Target Milestone: rc
: 6.2
Assignee: Rik van Riel
QA Contact: Yang Bai
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2011-06-07 20:46 UTC by Rik van Riel
Modified: 2011-12-06 13:33 UTC (History)
3 users (show)

Fixed In Version: kernel-2.6.32-177.el6
Doc Type: Bug Fix
Doc Text:
Red Hat Enterprise Linux 6.2 introduces a scheduling improvement where a hint is provided to the scheduler on the next buddy hint on sleep and preempt path. This hint/enhancement helps the workload of multiple tasks in multiple task groups.
Clone Of:
Environment:
Last Closed: 2011-12-06 13:33:25 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2011:1530 0 normal SHIPPED_LIVE Moderate: Red Hat Enterprise Linux 6 kernel security, bug fix and enhancement update 2011-12-06 01:45:35 UTC

Description Rik van Riel 2011-06-07 20:46:40 UTC 
Description of problem:

Backport the following patch from upstream.  I expect it will help JVM, KVM and more.

commit 2f36825b176f67e5c5228aa33d828bc39718811f
Author: Venkatesh Pallipadi <venki>
Date:   Thu Apr 14 10:30:53 2011 -0700

    sched: Next buddy hint on sleep and preempt path

    When a task in a taskgroup sleeps, pick_next_task starts all the way back at
    the root and picks the task/taskgroup with the min vruntime across all
    runnable tasks.

    But when there are many frequently sleeping tasks across different taskgroups,
    it makes better sense to stay with same taskgroup for its slice period (or
    until all tasks in the taskgroup sleeps) instead of switching cross taskgroup
    on each sleep after a short runtime.

    This helps specifically where taskgroups corresponds to a process with
    multiple threads. The change reduces the number of CR3 switches in this case.
Comment 1 RHEL Program Management 2011-06-08 18:59:59 UTC 
This request was evaluated by Red Hat Product Management for inclusion
in a Red Hat Enterprise Linux maintenance release. Product Management has 
requested further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed 
products. This request is not yet committed for inclusion in an Update release.
Comment 6 Aristeu Rozanski 2011-08-04 12:49:57 UTC 
Patch(es) available on kernel-2.6.32-177.el6
Comment 9 Linda Wang 2011-08-21 17:28:19 UTC 
    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:
RHEL6.2 backports a scheduling improvement of providing a hint to the scheduler on the next buddy hint on sleep and preempt path. This hint/enhacement helps the workload of mutiple tasks in multiple taskgroups.
Comment 12 Rik van Riel 2011-11-01 15:22:47 UTC 
Looks good to me.
Comment 13 Yang Bai 2011-11-02 01:52:30 UTC 
per comment 11 and comment 12, set this to VERIFIED.
Comment 14 Martin Prpič 2011-11-10 12:33:06 UTC 
    Technical note updated. If any revisions are required, please edit the "Technical Notes" field
    accordingly. All revisions will be proofread by the Engineering Content Services team.
    
    Diffed Contents:
@@ -1 +1 @@
-RHEL6.2 backports a scheduling improvement of providing a hint to the scheduler on the next buddy hint on sleep and preempt path. This hint/enhacement helps the workload of mutiple tasks in multiple taskgroups.+Red Hat Enterprise Linux 6.2 introduces a scheduling improvement where a hint is provided to the scheduler on the next buddy hint on sleep and preempt path. This hint/enhancement helps the workload of multiple tasks in multiple task groups.
Comment 15 errata-xmlrpc 2011-12-06 13:33:25 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.

http://rhn.redhat.com/errata/RHSA-2011-1530.html
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