From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx149.postini.com [74.125.245.149]) by kanga.kvack.org (Postfix) with SMTP id B083C6B005A for ; Wed, 9 Jan 2013 16:39:38 -0500 (EST) Received: by mail-pb0-f50.google.com with SMTP id wz7so1204549pbc.23 for ; Wed, 09 Jan 2013 13:39:37 -0800 (PST) Date: Wed, 9 Jan 2013 13:36:04 -0800 From: Anton Vorontsov Subject: Re: [PATCH 1/2] Add mempressure cgroup Message-ID: <20130109213604.GA9475@lizard.fhda.edu> References: <20130104082751.GA22227@lizard.gateway.2wire.net> <1357288152-23625-1-git-send-email-anton.vorontsov@linaro.org> <20130109203731.GA20454@htj.dyndns.org> <50EDDF1E.6010705@parallels.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <50EDDF1E.6010705@parallels.com> Sender: owner-linux-mm@kvack.org List-ID: To: Glauber Costa Cc: Tejun Heo , David Rientjes , Pekka Enberg , Mel Gorman , Michal Hocko , "Kirill A. Shutemov" , Luiz Capitulino , Andrew Morton , Greg Thelen , Leonid Moiseichuk , KOSAKI Motohiro , Minchan Kim , Bartlomiej Zolnierkiewicz , John Stultz , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linaro-kernel@lists.linaro.org, patches@linaro.org, kernel-team@android.com On Thu, Jan 10, 2013 at 01:20:30AM +0400, Glauber Costa wrote: [...] > Given the above, I believe that ideally we should use this pressure > mechanism in memcg replacing the current memcg notification mechanism. Just a quick wonder: why would we need to place it into memcg, when we don't need any of the memcg stuff for it? I see no benefits, not design-wise, not implementation-wise or anything-wise. :) We can use mempressure w/o memcg, and even then it can (or should :) be useful (for cpuset, for example). > More or less like timer expiration happens: you could still write > numbers for compatibility, but those numbers would be internally mapped > into the levels Anton is proposing, that makes *way* more sense. > > If that is not possible, they should coexist as "notification" and a > "pressure" mechanism inside memcg. > > The main argument against it centered around cpusets also being able to > participate in the play. I haven't yet understood how would it take > place. In particular, I saw no mention to cpusets in the patches. I didn't test it, but as I see it, once a process in a specific cpuset, the task can only use a specific allowed zones for reclaim/alloc, i.e. various checks like this in vmscan: if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL)) continue; So, vmscan simply won't call vmpressure() if the zone is not allowed (so we won't account that pressure, from that zone). Thanks, Anton -- 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