From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <owner-linux-mm@kvack.org>
Received: from mail6.bemta7.messagelabs.com (mail6.bemta7.messagelabs.com [216.82.255.55])
	by kanga.kvack.org (Postfix) with ESMTP id DF5F66B0012
	for <linux-mm@kvack.org>; Wed, 15 Jun 2011 12:42:08 -0400 (EDT)
Received: from j77219.upc-j.chello.nl ([24.132.77.219] helo=dyad.programming.kicks-ass.net)
	by casper.infradead.org with esmtpsa (Exim 4.76 #1 (Red Hat Linux))
	id 1QWtAL-0003RB-H0
	for linux-mm@kvack.org; Wed, 15 Jun 2011 16:42:05 +0000
Subject: Re: REGRESSION: Performance regressions from switching
 anon_vma->lock to mutex
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
In-Reply-To: <20110615161827.GA11769@tassilo.jf.intel.com>
References: <1308097798.17300.142.camel@schen9-DESK>
	 <1308101214.15392.151.camel@sli10-conroe> <1308138750.15315.62.camel@twins>
	 <20110615161827.GA11769@tassilo.jf.intel.com>
Content-Type: text/plain; charset="UTF-8"
Date: Wed, 15 Jun 2011 18:45:37 +0200
Message-ID: <1308156337.2171.23.camel@laptop>
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit
Sender: owner-linux-mm@kvack.org
List-ID: <linux-mm.kvack.org>
To: Andi Kleen <ak@linux.intel.com>
Cc: Shaohua Li <shaohua.li@intel.com>, Tim Chen <tim.c.chen@linux.intel.com>, Andrew Morton <akpm@linux-foundation.org>, Linus Torvalds <torvalds@linux-foundation.org>, Hugh Dickins <hughd@google.com>, KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, David Miller <davem@davemloft.net>, Martin Schwidefsky <schwidefsky@de.ibm.com>, Russell King <rmk@arm.linux.org.uk>, Paul Mundt <lethal@linux-sh.org>, Jeff Dike <jdike@addtoit.com>, Richard Weinberger <richard@nod.at>, "Luck,
 Tony" <tony.luck@intel.com>, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>, Mel Gorman <mel@csn.ul.ie>, Nick Piggin <npiggin@kernel.dk>, Namhyung Kim <namhyung@gmail.com>, "Shi, Alex" <alex.shi@intel.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "linux-mm@kvack.org" <linux-mm@kvack.org>, "Rafael J. Wysocki" <rjw@sisk.pl>

On Wed, 2011-06-15 at 09:18 -0700, Andi Kleen wrote:

> And in general it looks like blind conversion from spinlock to mutex
> is a bad idea right now.

For 4 socket machines, maybe. On 2 sockets I cannot reproduce anything.

I wonder if its the fairness thing, the mutex spinners aren't fifo fair
like the ticket locks are. It could be significant with larger socket
count since their cacheline arbitration is more sucky.



--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>