Re: REGRESSION: Performance regressions from switchinganon_vma->lock to mutex

From: Ingo Molnar
Date: Sat Jun 18 2011 - 04:09:36 EST

* Andi Kleen <ak@xxxxxxxxxxxxxxx> wrote:

> On Fri, Jun 17, 2011 at 09:46:00AM -0700, Linus Torvalds wrote:
> > On Fri, Jun 17, 2011 at 4:28 AM, Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> wrote:
> > >
> > > Something like so? Compiles and runs the benchmark in question.
> >
> > Oh, and can you do this with a commit log and sign-off, and I'll put
> > it in my "anon_vma-locking" branch that I have. I'm not going to
> > actually merge that branch into mainline until I've seen a few more
> > acks or more testing by Tim.
> >
> > But if Tim's numbers hold up (-32% to +15% performance by just the
> > first one, and +15% isn't actually an improvement since tmpfs
> > read-ahead should have gotten us to +66%), I think we have to do this
> > just to avoid the performance regression.
> You could also add the mutex "optimize caching protocol"
> patch I posted earlier to that branch.
> It didn't actually improve Tim's throughput number, but it made the
> CPU consumption of the mutex go down.

Why have you ignored the negative feedback for that patch:

and why have you resent this patch without addressing that feedback?


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