From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with SMTP id 300506B003D for ; Sun, 5 Apr 2009 23:56:47 -0400 (EDT) Received: from m5.gw.fujitsu.co.jp ([10.0.50.75]) by fgwmail6.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id n363vcUj013604 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Mon, 6 Apr 2009 12:57:38 +0900 Received: from smail (m5 [127.0.0.1]) by outgoing.m5.gw.fujitsu.co.jp (Postfix) with ESMTP id 9372B45DE54 for ; Mon, 6 Apr 2009 12:57:38 +0900 (JST) Received: from s5.gw.fujitsu.co.jp (s5.gw.fujitsu.co.jp [10.0.50.95]) by m5.gw.fujitsu.co.jp (Postfix) with ESMTP id 73A6D45DE4E for ; Mon, 6 Apr 2009 12:57:38 +0900 (JST) Received: from s5.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s5.gw.fujitsu.co.jp (Postfix) with ESMTP id 548AC1DB805F for ; Mon, 6 Apr 2009 12:57:38 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.249.87.105]) by s5.gw.fujitsu.co.jp (Postfix) with ESMTP id 0E0051DB8043 for ; Mon, 6 Apr 2009 12:57:38 +0900 (JST) From: KOSAKI Motohiro Subject: Re: + mm-align-vmstat_works-timer.patch added to -mm tree In-Reply-To: <20090406120533.450B.A69D9226@jp.fujitsu.com> References: <200904011945.n31JjWqG028114@imap1.linux-foundation.org> <20090406120533.450B.A69D9226@jp.fujitsu.com> Message-Id: <20090406125627.4514.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Mon, 6 Apr 2009 12:57:37 +0900 (JST) Sender: owner-linux-mm@kvack.org To: KOSAKI Motohiro Cc: linux-kernel@vger.kernel.org, anton@samba.org, linux-mm , Andrew Morton List-ID: > (swich to lkml and linux-mm) > > Hi Anton, > > Do you have any mesurement data? > > Honestly, I made the same patch few week ago. > but I found two problems. > > 1) > work queue tracer (in -tip) reported it isn't proper rounded. Ah, sorry ignore this sentence. I used my local patch queue's feature for mesurement, not -tip. > > The fact is, schedule_delayed_work(work, round_jiffies_relative()) is > a bit ill. > > it mean > - round_jiffies_relative() calculate rounded-time - jiffies > - schedule_delayed_work() calculate argument + jiffies > > it assume no jiffies change at above two place. IOW it assume > non preempt kernel. > > > 2) > > - schedule_delayed_work_on(cpu, vmstat_work, HZ + cpu); > > + schedule_delayed_work_on(cpu, vmstat_work, > > + __round_jiffies_relative(HZ, cpu)); > > isn't same meaning. > > vmstat_work mean to move per-cpu stastics to global stastics. > Then, (HZ + cpu) mean to avoid to touch the same global variable at the same time. > > Oh well, this patch have performance regression risk on _very_ big server. > (perhaps, only sgi?) > > but I agree vmstat_work is one of most work queue heavy user. > For power consumption view, it isn't proper behavior. > > I still think improving another way. -- 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