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 B05AE6B012D for ; Wed, 13 Oct 2010 22:39:38 -0400 (EDT) Received: from m2.gw.fujitsu.co.jp ([10.0.50.72]) by fgwmail7.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o9E2dabv005070 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Thu, 14 Oct 2010 11:39:36 +0900 Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id F26F045DE51 for ; Thu, 14 Oct 2010 11:39:35 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (s2.gw.fujitsu.co.jp [10.0.50.92]) by m2.gw.fujitsu.co.jp (Postfix) with ESMTP id D47CE45DE4F for ; Thu, 14 Oct 2010 11:39:35 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id B88821DB8038 for ; Thu, 14 Oct 2010 11:39:35 +0900 (JST) Received: from m108.s.css.fujitsu.com (m108.s.css.fujitsu.com [10.249.87.108]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 7720C1DB803A for ; Thu, 14 Oct 2010 11:39:35 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [RFC][PATCH 3/3] mm: reserve max drift pages at boot time instead using zone_page_state_snapshot() In-Reply-To: <20101013131916.GN30667@csn.ul.ie> References: <20101013152922.ADC6.A69D9226@jp.fujitsu.com> <20101013131916.GN30667@csn.ul.ie> Message-Id: <20101014113426.8B83.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Thu, 14 Oct 2010 11:39:34 +0900 (JST) Sender: owner-linux-mm@kvack.org To: Mel Gorman Cc: kosaki.motohiro@jp.fujitsu.com, Shaohua Li , "linux-mm@kvack.org" , "cl@linux.com" , Andrew Morton , David Rientjes , KAMEZAWA Hiroyuki List-ID: > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index 53627fa..194bdaa 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -4897,6 +4897,15 @@ static void setup_per_zone_wmarks(void) > > for_each_zone(zone) { > > u64 tmp; > > > > + /* > > + * If max drift are less than 1%, reserve max drift pages > > + * instead costly runtime calculation. > > + */ > > + if (zone->percpu_drift_mark < (zone->present_pages/100)) { > > + pages_min += zone->percpu_drift_mark; > > + zone->percpu_drift_mark = 0; > > + } > > + > > I don't see how this solves Shaohua's problem as such. Large systems will > still suffer a bug performance penalty from zone_page_state_snapshot(). I > do see the logic of adjusting min for larger systems to limit the amount of > time per-cpu thresholds are lowered but that would be as a follow-on to my > patch rather than a replacement. My patch rescue 256cpus or more smaller systems. and I assumed 4096cpus system don't run IO intensive workload such as Shaohua's case. they always use cpusets and run hpc workload. If you know another >1024cpus system, please let me know. And again, my patch works on 4096cpus sysmtem although slow, but your don't. Am I missing something? -- 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