From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with ESMTP id 1CA0B5F0001 for ; Mon, 20 Apr 2009 12:15:25 -0400 (EDT) Received: from d01relay04.pok.ibm.com (d01relay04.pok.ibm.com [9.56.227.236]) by e7.ny.us.ibm.com (8.13.1/8.13.1) with ESMTP id n3KG5BAT005624 for ; Mon, 20 Apr 2009 12:05:11 -0400 Received: from d01av02.pok.ibm.com (d01av02.pok.ibm.com [9.56.224.216]) by d01relay04.pok.ibm.com (8.13.8/8.13.8/NCO v9.2) with ESMTP id n3KGFRVw181664 for ; Mon, 20 Apr 2009 12:15:27 -0400 Received: from d01av02.pok.ibm.com (loopback [127.0.0.1]) by d01av02.pok.ibm.com (8.12.11.20060308/8.13.3) with ESMTP id n3KGDetn005205 for ; Mon, 20 Apr 2009 12:13:42 -0400 Subject: Re: [PATCH V3] Fix Committed_AS underflow From: Dave Hansen In-Reply-To: <1240218590-16714-1-git-send-email-ebmunson@us.ibm.com> References: <1240218590-16714-1-git-send-email-ebmunson@us.ibm.com> Content-Type: text/plain Date: Mon, 20 Apr 2009 09:15:20 -0700 Message-Id: <1240244120.32604.278.camel@nimitz> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Eric B Munson Cc: kosaki.motohiro@jp.fujitsu.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, mel@linux.vnet.ibm.com, cl@linux-foundation.org List-ID: On Mon, 2009-04-20 at 10:09 +0100, Eric B Munson wrote: > 1. Change NR_CPUS to min(64, NR_CPUS) > This will limit the amount of possible skew on kernels compiled for very > large SMP machines. 64 is an arbitrary number selected to limit the worst > of the skew without using more cache lines. min(64, NR_CPUS) is used > instead of nr_online_cpus() because nr_online_cpus() requires a shared > cache line and a call to hweight to make the calculation. Its runtime > overhead and keeping this counter accurate showed up in profiles and it's > possible that nr_online_cpus() would also show. -- Dave -- 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/ . Don't email: email@kvack.org