linux-kernel - Re: REGRESSION: Performance regressions from switching anon

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Message-ID: <20110618080818.GA10351@elte.hu>
Date:	Sat, 18 Jun 2011 10:08:18 +0200
From:	Ingo Molnar <mingo@...e.hu>
To:	Andi Kleen <ak@...ux.intel.com>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Tim Chen <tim.c.chen@...ux.intel.com>,
	Shaohua Li <shaohua.li@...el.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Hugh Dickins <hughd@...gle.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	David Miller <davem@...emloft.net>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Russell King <rmk@....linux.org.uk>,
	Paul Mundt <lethal@...ux-sh.org>,
	Jeff Dike <jdike@...toit.com>,
	Richard Weinberger <richard@....at>,
	"Luck, Tony" <tony.luck@...el.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Mel Gorman <mel@....ul.ie>, Nick Piggin <npiggin@...nel.dk>,
	Namhyung Kim <namhyung@...il.com>,
	"Shi, Alex" <alex.shi@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>
Subject: Re: REGRESSION: Performance regressions from switching
 anon_vma->lock to mutex


* Andi Kleen <ak@...ux.intel.com> 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@...llo.nl> 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:

  http://marc.info/?i=20110617190705.GA26824@elte.hu

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

Thanks,

	Ingo
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