From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f199.google.com (mail-pf0-f199.google.com [209.85.192.199]) by kanga.kvack.org (Postfix) with ESMTP id 6AB3C6B0033 for ; Mon, 23 Jan 2017 15:55:05 -0500 (EST) Received: by mail-pf0-f199.google.com with SMTP id 204so215710997pfx.1 for ; Mon, 23 Jan 2017 12:55:05 -0800 (PST) Received: from mail-pg0-x243.google.com (mail-pg0-x243.google.com. [2607:f8b0:400e:c05::243]) by mx.google.com with ESMTPS id c10si10203830pfj.210.2017.01.23.12.55.04 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 23 Jan 2017 12:55:04 -0800 (PST) Received: by mail-pg0-x243.google.com with SMTP id t6so14587061pgt.1 for ; Mon, 23 Jan 2017 12:55:04 -0800 (PST) Date: Mon, 23 Jan 2017 15:55:01 -0500 From: Tejun Heo Subject: Re: [PATCH 3/4] mm, page_alloc: Drain per-cpu pages from workqueue context Message-ID: <20170123205501.GA25944@htj.duckdns.org> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170123200412.mkesardc4mckk6df@techsingularity.net> Sender: owner-linux-mm@kvack.org List-ID: To: Mel Gorman Cc: Vlastimil Babka , Andrew Morton , Linux Kernel , Linux-MM , Hillf Danton , Jesper Dangaard Brouer , Petr Mladek 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. On this area, the current workqueue behavior is pretty bad. Historically, we didn't distinguish affinity-for-optimization affinity-for-correctness, so we couldn't really enforce strong behaviors on it. We started distinguishing them some releases ago, so I should revisit it soon. Thanks. -- tejun -- 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