Re: Linux kernel performance regressions

[Aris Setyawan <aris.sety@gmail.com>]

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/
>
>