Re: [PATCH 0/5] x86,smp: make ticket spinlock proportional backoffw/ auto tuning

From: Mike Galbraith
Date: Thu Jan 10 2013 - 14:30:16 EST


On Thu, 2013-01-10 at 10:31 -0500, Rik van Riel wrote:
> On 01/10/2013 10:19 AM, Mike Galbraith wrote:
> > On Tue, 2013-01-08 at 17:26 -0500, Rik van Riel wrote:
> >
> >> Please let me know if you manage to break this code in any way,
> >> so I can fix it...
> >
> > I didn't break it, but did let it play with rq->lock contention. Using
> > cyclictest -Smp99 -i 100 -d 0, with 3 rt tasks for pull_rt_task() to
> > pull around appears to have been a ~dead heat.
>
> Good to hear that the code seems to be robust. It seems to
> help prevent performance degradation in some workloads, and
> nobody seems to have found regressions yet.

I had hoped for a bit of positive, but a wash isn't surprising given the
profile. I tried tbench too, didn't expect to see anything at all
there, and got that.. so both results are positive in that respect.

-Mike

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