From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with SMTP id 219F56B0031 for ; Thu, 13 Oct 2011 11:54:36 -0400 (EDT) Date: Thu, 13 Oct 2011 10:54:30 -0500 (CDT) From: Christoph Lameter Subject: Re: [PATCH] Reduce vm_stat cacheline contention in __vm_enough_memory In-Reply-To: <20111013152355.GB6966@sgi.com> Message-ID: References: <20111012160202.GA18666@sgi.com> <20111012120118.e948f40a.akpm@linux-foundation.org> <20111013152355.GB6966@sgi.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Dimitri Sivanich Cc: Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Mel Gorman On Thu, 13 Oct 2011, Dimitri Sivanich wrote: > > increase the allowed delta per zone if frequent updates occur via the > > overflow checks in vmstat.c. See calculate_*_threshold there. > > I tried changing the threshold in both directions, with slower throughput in > both cases. If that is the case check for the vm_stat cacheline being shared with another hot kernel variable variable. Maybe that causes cacheline eviction. If there are no updates occurring for a while (due to increased deltas and/or vmstat updates) then the vm_stat cacheline should be able to stay in shared mode in multiple processors and the performance should increase. -- 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: email@kvack.org