From mboxrd@z Thu Jan 1 00:00:00 1970 From: Marcelo Tosatti Subject: Re: [patch 2/2] MM: allow per-cpu vmstat_threshold and vmstat_worker configuration Date: Fri, 12 May 2017 09:27:06 -0300 Message-ID: <20170512122704.GA30528@amt.cnet> References: <20170425135717.375295031@redhat.com> <20170425135846.203663532@redhat.com> <20170502102836.4a4d34ba@redhat.com> <20170502165159.GA5457@amt.cnet> <20170502131527.7532fc2e@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Luiz Capitulino , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Rik van Riel , Linux RT Users , cmetcalf@mellanox.com To: Christoph Lameter Return-path: Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-Id: linux-rt-users.vger.kernel.org On Thu, May 11, 2017 at 10:37:07AM -0500, Christoph Lameter wrote: > On Tue, 2 May 2017, Luiz Capitulino wrote: > > > Ah, OK. Got this now. I'll give this patch a try. But I think we want > > to hear from Christoph (who worked on reducing the vmstat interruptions > > in the past). > > A bit confused by this one. The vmstat worker is already disabled if there > are no updates. Also the patches by Chris Metcalf on data plane mode add a > prctl to quiet the vmstat workers. > > Why do we need more than this? If there are vmstat statistic updates on a given CPU, and you don't want intervention from the vmstat worker, you change the behaviour of stat data collection to directly write to the global structures (which disables the performance optimization of collecting data in per-cpu counters). This way you can disable vmstat worker (because it causes undesired latencies), while allowing vmstatistics to function properly. The prctl from Chris Metcalf patchset allows one to disable vmstat worker per CPU? If so, they replace the functionality of the patch "[patch 3/3] MM: allow per-cpu vmstat_worker configuration" of the -v2 series of my patchset, and we can use it instead. Is it integrated already? -- 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756624AbdELM1d (ORCPT ); Fri, 12 May 2017 08:27:33 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33122 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750796AbdELM1b (ORCPT ); Fri, 12 May 2017 08:27:31 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 5415D81129 Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx03.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=mtosatti@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com 5415D81129 Date: Fri, 12 May 2017 09:27:06 -0300 From: Marcelo Tosatti To: Christoph Lameter Cc: Luiz Capitulino , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Rik van Riel , Linux RT Users , cmetcalf@mellanox.com Subject: Re: [patch 2/2] MM: allow per-cpu vmstat_threshold and vmstat_worker configuration Message-ID: <20170512122704.GA30528@amt.cnet> References: <20170425135717.375295031@redhat.com> <20170425135846.203663532@redhat.com> <20170502102836.4a4d34ba@redhat.com> <20170502165159.GA5457@amt.cnet> <20170502131527.7532fc2e@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Fri, 12 May 2017 12:27:30 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, May 11, 2017 at 10:37:07AM -0500, Christoph Lameter wrote: > On Tue, 2 May 2017, Luiz Capitulino wrote: > > > Ah, OK. Got this now. I'll give this patch a try. But I think we want > > to hear from Christoph (who worked on reducing the vmstat interruptions > > in the past). > > A bit confused by this one. The vmstat worker is already disabled if there > are no updates. Also the patches by Chris Metcalf on data plane mode add a > prctl to quiet the vmstat workers. > > Why do we need more than this? If there are vmstat statistic updates on a given CPU, and you don't want intervention from the vmstat worker, you change the behaviour of stat data collection to directly write to the global structures (which disables the performance optimization of collecting data in per-cpu counters). This way you can disable vmstat worker (because it causes undesired latencies), while allowing vmstatistics to function properly. The prctl from Chris Metcalf patchset allows one to disable vmstat worker per CPU? If so, they replace the functionality of the patch "[patch 3/3] MM: allow per-cpu vmstat_worker configuration" of the -v2 series of my patchset, and we can use it instead. Is it integrated already?