[CentOS-devel] Kernel bug fix that restores SSD performance -- testing sought

Akemi Yagi amyagi at gmail.com
Tue Sep 3 16:21:08 UTC 2013


On Thu, Jul 18, 2013 at 3:47 PM, Akemi Yagi <amyagi at gmail.com> wrote:
> On Thu, Jul 18, 2013 at 2:07 PM, Karanbir Singh <mail-lists at karan.org> wrote:

>> Which then has me thinking - what is the actual problem we are trying to
>> solve here ? and how can I ratify that ?
>
> All details are given in CentOS bug #6548 (links therein) but here's
> is a short summary of the events that were seen in the kernel
> development [list].
>
> Someone reported "bad performance with SSD since kernel version
> 2.6.32". After bisection, he found the following commit to be the
> likely culprit:
>
> commit fb1e75389bd06fd5987e9cda1b4e0305c782f854
> Author: Jens Axboe <jens.axboe at xxxxxxxxxx>
> Date:   Thu Jul 30 08:18:24 2009 +0200
> (This was added to kernel 2.6.32)
>
> Long story short, this commit was reverted in kernel 2.6.33:
>
> commit 79da0644a8e0838522828f106e4049639eea6baf
> Author: Jens Axboe <jens.axboe at oracle.com>
> Date: Tue Feb 23 08:40:43 2010 +0100
(snip)

Just wanted to update the status of the issue.

(1) Current centosplus kernel 2.6.32-358.18.1.el6.centos.plus has the
patch from the second commit quoted above that is supposed to rectify
the issue.

(2) I've filed a bug report upstream:

https://bugzilla.redhat.com/show_bug.cgi?id=1003678
 (It's marked private)

>From the way it looks, the patch will be pulled in to the RHEL kernel
but no specific version is given.

Akemi


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