linux-kernel - Re: [PATCH 2/2] mutex: Apply adaptive spinning on mutex

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Message-ID: <20110325103138.GC31903@elte.hu>
Date:	Fri, 25 Mar 2011 11:31:38 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Tejun Heo <tj@...nel.org>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Chris Mason <chris.mason@...cle.com>,
	linux-kernel@...r.kernel.org, linux-btrfs@...r.kernel.org
Subject: Re: [PATCH 2/2] mutex: Apply adaptive spinning on mutex_trylock()


* Tejun Heo <tj@...nel.org> wrote:

> Hello,
> 
> On Thu, Mar 24, 2011 at 10:41:51AM +0100, Tejun Heo wrote:
> >         USER   SYSTEM   SIRQ    CXTSW  THROUGHPUT
> >  SIMPLE 61107  354977    217  8099529  845.100 MB/sec
> >  SPIN   63140  364888    214  6840527  879.077 MB/sec
> > 
> > On various runs, the adaptive spinning trylock consistently posts
> > higher throughput.  The amount of difference varies but it outperforms
> > consistently.
> 
> I've been running more of these tests and am having doubts about the
> consistency.  It seems that, even on a fresh filesystem, some random
> initial condition seems to have persistent effect on the whole run.
> I'll run more tests and report back.

Ok, and there's the deadlock issue as well which Steve noticed.

I'll zap the patches from tip:core/urgent and lets do this via tip:core/locking 
with a .40 timeframe and plenty of time of testing.

Thanks,

	Ingo
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