Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758641Ab3HMXck (ORCPT ); Tue, 13 Aug 2013 19:32:40 -0400 Received: from usmamail.tilera.com ([12.216.194.151]:37322 "EHLO USMAMAIL.TILERA.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755311Ab3HMXck (ORCPT ); Tue, 13 Aug 2013 19:32:40 -0400 Message-ID: <520AC215.4050803@tilera.com> Date: Tue, 13 Aug 2013 19:32:37 -0400 From: Chris Metcalf User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130620 Thunderbird/17.0.7 MIME-Version: 1.0 To: Tejun Heo CC: Andrew Morton , , , Thomas Gleixner , Frederic Weisbecker , Cody P Schafer Subject: Re: [PATCH v7 2/2] mm: make lru_add_drain_all() selective References: <520AAF9C.1050702@tilera.com> <201308132307.r7DN74M5029053@farm-0021.internal.tilera.com> <20130813232904.GJ28996@mtj.dyndns.org> In-Reply-To: <20130813232904.GJ28996@mtj.dyndns.org> X-Enigmail-Version: 1.5.2 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1326 Lines: 35 On 8/13/2013 7:29 PM, Tejun Heo wrote: > Hello, > > On Tue, Aug 13, 2013 at 06:53:32PM -0400, Chris Metcalf wrote: >> int lru_add_drain_all(void) >> { >> - return schedule_on_each_cpu(lru_add_drain_per_cpu); >> + return schedule_on_each_cpu_cond(lru_add_drain_per_cpu, >> + lru_add_drain_cond, NULL); > It won't nest and doing it simultaneously won't buy anything, right? Correct on both counts, I think. > Wouldn't it be better to protect it with a mutex and define all > necessary resources statically (yeah, cpumask is pain in the ass and I > think we should un-deprecate cpumask_t for static use cases)? Then, > there'd be no allocation to worry about on the path. If allocation is a real problem on this path, I think this is probably OK, though I don't want to speak for Andrew. You could just guard it with a trylock and any caller that tried to start it while it was locked could just return happy that it was going on. I'll put out a version that does that and see how that looks for comparison's sake. -- Chris Metcalf, Tilera Corp. http://www.tilera.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/