linux-kernel - Re: [Bugme-new] [Bug 15618] New: 2.6.18->2.6.32->2.6.33 huge regression in performance

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Message-ID: <alpine.LFD.2.00.1003231253570.18017@i5.linux-foundation.org>
Date:	Tue, 23 Mar 2010 12:54:47 -0700 (PDT)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Anton Starikov <ant.starikov@...il.com>
cc:	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, bugzilla-daemon@...zilla.kernel.org,
	bugme-daemon@...zilla.kernel.org,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Subject: Re: [Bugme-new] [Bug 15618] New: 2.6.18->2.6.32->2.6.33 huge regression
 in performance



On Tue, 23 Mar 2010, Anton Starikov wrote:

> 
> On Mar 23, 2010, at 6:45 PM, Linus Torvalds wrote:
> 
> > 
> > 
> > On Tue, 23 Mar 2010, Ingo Molnar wrote:
> >> 
> >> It shows a very brutal amount of page fault invoked mmap_sem spinning 
> >> overhead.
> > 
> > Isn't this already fixed? It's the same old "x86-64 rwsemaphores are using 
> > the shit-for-brains generic version" thing, and it's fixed by
> > 
> > 	1838ef1 x86-64, rwsem: 64-bit xadd rwsem implementation
> > 	5d0b723 x86: clean up rwsem type system
> > 	59c33fa x86-32: clean up rwsem inline asm statements
> > 
> > NOTE! None of those are in 2.6.33 - they were merged afterwards. But they 
> > are in 2.6.34-rc1 (and obviously current -git). So Anton would have to 
> > compile his own kernel to test his load.
> 
> 
> Applied mentioned patches. Things didn't improve too much.

Yeah, I missed at least one commit, namely

	bafaecd x86-64: support native xadd rwsem implementation

which is the one that actually makes x86-64 able to use the xadd version.

		Linus
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