Re: [PATCH 0/3 v2] mutex: Improve mutex performance by doing less atomic-ops & better spinning

[Ingo Molnar <mingo@kernel.org>]

* Waiman Long <Waiman.Long@hp.com> wrote:

> On 04/16/2013 05:12 AM, Ingo Molnar wrote:
> >* Waiman Long<Waiman.Long@hp.com>  wrote:
> >
> >>[...]
> >>
> >>Patches 2 improves the mutex spinning process by reducing contention among the
> >>spinners when competing for the mutex. This is done by using a MCS lock to put
> >>the spinners in a queue so that only the first spinner will try to acquire the
> >>mutex when it is available. This patch showed significant performance
> >>improvement of +30% on the AIM7 fserver and new_fserver workload.
> >Ok, that's really nice - and this approach has no arbitrary limits/tunings in it.
> >
> >Do you have a performance comparison to your first series (patches 1+2+3 IIRC) -
> >how does this new series with MCS locking compare to the best previous result from
> >that old series? Do we now achieve that level of performance?
> 
> Compared with the old patch set, the new patches 1+2 have over 30%
> performance gain in high user load (1100-1500) in the fserver and
> new_fserver workloads. The old patches 1+2 or 1+3 only manages
> around 10% gain. In the intermediate range of 200-1000, the 2 sets
> are more comparable in performance gain.

Ok, that's cool!

Thanks,

	Ingo