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

[Waiman Long]

On 04/16/2013 05:12 AM, Ingo Molnar wrote:
> * Waiman Long<Waiman.Long@xxxxxx>  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.

Regards,
Longman
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