From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750989AbdAWXEd (ORCPT ); Mon, 23 Jan 2017 18:04:33 -0500 Received: from outbound-smtp02.blacknight.com ([81.17.249.8]:57619 "EHLO outbound-smtp02.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750709AbdAWXEc (ORCPT ); Mon, 23 Jan 2017 18:04:32 -0500 Date: Mon, 23 Jan 2017 23:04:29 +0000 From: Mel Gorman To: Tejun Heo Cc: Vlastimil Babka , Andrew Morton , Linux Kernel , Linux-MM , Hillf Danton , Jesper Dangaard Brouer , Petr Mladek Subject: Re: [PATCH 3/4] mm, page_alloc: Drain per-cpu pages from workqueue context Message-ID: <20170123230429.os7ssxab4mazrkrb@techsingularity.net> References: <20170117092954.15413-1-mgorman@techsingularity.net> <20170117092954.15413-4-mgorman@techsingularity.net> <06c39883-eff5-1412-a148-b063aa7bcc5f@suse.cz> <20170120152606.w3hb53m2w6thzsqq@techsingularity.net> <20170123170329.GA7820@htj.duckdns.org> <20170123200412.mkesardc4mckk6df@techsingularity.net> <20170123205501.GA25944@htj.duckdns.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <20170123205501.GA25944@htj.duckdns.org> User-Agent: Mutt/1.6.2 (2016-07-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 23, 2017 at 03:55:01PM -0500, Tejun Heo wrote: > Hello, Mel. > > On Mon, Jan 23, 2017 at 08:04:12PM +0000, Mel Gorman wrote: > > What is the actual mechanism that does that? It's not something that > > schedule_on_each_cpu does and one would expect that the core workqueue > > implementation would get this sort of detail correct. Or is this a proposal > > on how it should be done? > > If you use schedule_on_each_cpu(), it's all fine as the thing pins > cpus and waits for all the work items synchronously. If you wanna do > it asynchronously, right now, you'll have to manually synchronize work > items against the offline callback manually. > Is the current implementation and what it does wrong in some way? I ask because synchronising against the offline callback sounds like it would be a bit of a maintenance mess for relatively little gain. -- Mel Gorman SUSE Labs