From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx171.postini.com [74.125.245.171]) by kanga.kvack.org (Postfix) with SMTP id 3AEF26B0044 for ; Mon, 7 May 2012 15:40:17 -0400 (EDT) Date: Mon, 7 May 2012 14:40:11 -0500 (CDT) From: Christoph Lameter Subject: Re: [PATCH v1 5/6] mm: make vmstat_update periodic run conditional In-Reply-To: <4FA823A7.9000801@gmail.com> Message-ID: References: <1336056962-10465-1-git-send-email-gilad@benyossef.com> <1336056962-10465-6-git-send-email-gilad@benyossef.com> <4FA823A7.9000801@gmail.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: KOSAKI Motohiro Cc: Gilad Ben-Yossef , linux-kernel@vger.kernel.org, Thomas Gleixner , Tejun Heo , John Stultz , Andrew Morton , KOSAKI Motohiro , Mel Gorman , Mike Frysinger , David Rientjes , Hugh Dickins , Minchan Kim , Konstantin Khlebnikov , Chris Metcalf , Hakan Akkan , Max Krasnyansky , Frederic Weisbecker , linux-mm@kvack.org On Mon, 7 May 2012, KOSAKI Motohiro wrote: > > > @@ -1204,8 +1265,14 @@ static int __init setup_vmstat(void) > > > > > > register_cpu_notifier(&vmstat_notifier); > > > > > > + INIT_DELAYED_WORK_DEFERRABLE(&vmstat_monitor_work, > > > + vmstat_update_monitor); > > > + queue_delayed_work(system_unbound_wq, > > > + &vmstat_monitor_work, > > > + round_jiffies_relative(HZ)); > > > + > > > for_each_online_cpu(cpu) > > > - start_cpu_timer(cpu); > > > + setup_cpu_timer(cpu); > > > #endif > > > #ifdef CONFIG_PROC_FS > > > proc_create("buddyinfo", S_IRUGO, > > > NULL,&fragmentation_file_operations); > > > > So the monitoring thread just bounces around the system? Hope that the > > scheduler does the right thing to keep it on processors that do some other > > work. > > Good point. Usually, all cpus have update items and monitor worker only makes > new noise. I think this feature is only useful some hpc case. So I wonder if > this vmstat improvemnt can integrate Frederic's Nohz cpusets activity. I.e. > vmstat-update integrate timer house keeping and automatically stop when > stopping > hz house keeping. Right. We could do the same processing in vmstat update and the thread could check if it is the last vmstat update thread. If so simply continue and do not terminate. But this would still mean that the vmstat update thread would run on an arbitrary cpu. If I have a sacrificial lamb processor for OS processing then I would expect the vmstat update thread to stick to that processor and avoid to run on the other processor that I would like to be as free from OS noise as possible. -- 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