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Re: Linux kernel performance regressions

Maybe related to this bug/feature:

http://ubuntuforums.org/showthread.php?t=2179879
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1188647

On 12/13/13, Aris Setyawan <aris.sety@gmail.com> wrote:
> Is this mean, that we can't use all of CPU's power with 3.12 kernel?
>
> On 12/11/13, Howard Chu <hyc@symas.com> wrote:
>>
>>
>> -------- Original Message --------
>> Subject: Linux kernel performance regressions
>> Date: Wed, 11 Dec 2013 04:33:06 -0800
>> From: Howard Chu <hyc@symas.com>
>> To: OpenLDAP-devel@openldap.org <OpenLDAP-devel@openldap.org>
>>
>> We upgraded from kernel 3.5 to 3.12.3 to update some of our benchmark
>> numbers
>> and hit some major performance regressions, mainly because the kernel is
>> throttling processes that use too much CPU. This is definitely a kernel
>> bug,
>> as the throttle mechanism belongs to the realtime scheduler and none of
>> the
>> processes being affected had realtime priority when the throttle kicked
>> in.
>>
>> I've posted a query to the linux kernel mailing list but haven't gotten
>> any
>> satisfactory answers yet. The same throttling behavior also occurs with
>> 3.11.10, but there are no corresponding messages in the kernel log.
>>
>> The email thread is here
>> http://lkml.indiana.edu/hypermail/linux/kernel/1312.1/02313.html
>>
>> A patch that may be related is described here
>> http://lkml.org/lkml/2013/5/29/640 which explains part of the observed
>> behavior, but not all of it (and indeed may be a red herring, unless it
>> has
>> some interaction with the realtime scheduler).
>>
>> There appear to be other serious networking related regressions in 3.12
>> as
>> well. http://lkml.indiana.edu/hypermail/linux/kernel/1312.1/02588.html
>>
>> I recommend staying on 3.10 for production servers until this is sorted
>> out.
>>
>> --
>>     -- Howard Chu
>>     CTO, Symas Corp.           http://www.symas.com
>>     Director, Highland Sun     http://highlandsun.com/hyc/
>>     Chief Architect, OpenLDAP  http://www.openldap.org/project/
>>
>>
>