From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx123.postini.com [74.125.245.123]) by kanga.kvack.org (Postfix) with SMTP id 4D1556B004D for ; Wed, 21 Dec 2011 20:17:20 -0500 (EST) Received: by ggni2 with SMTP id i2so7873969ggn.14 for ; Wed, 21 Dec 2011 17:17:19 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <4EF132EA.7000300@am.sony.com> References: <20111219025328.GA26249@oksana.dev.rtsoft.ru> <20111219121255.GA2086@tiehlicka.suse.cz> <20111220145654.GA26881@oksana.dev.rtsoft.ru> <20111221002853.GA11504@oksana.dev.rtsoft.ru> <4EF132EA.7000300@am.sony.com> From: KOSAKI Motohiro Date: Wed, 21 Dec 2011 20:16:58 -0500 Message-ID: Subject: Re: Android low memory killer vs. memory pressure notifications Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: frank.rowand@am.sony.com Cc: Anton Vorontsov , David Rientjes , Michal Hocko , =?ISO-8859-1?Q?Arve_Hj=F8nnev=E5g?= , Rik van Riel , Pavel Machek , Greg Kroah-Hartman , Andrew Morton , John Stultz , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , Johannes Weiner , KAMEZAWA Hiroyuki , Alan Cox , tbird20d@gmail.com >> So for 2MB kernel that's about 20KB of an additional text... This seems >> affordable, especially as a trade-off for the things that cgroups may >> provide. > > A comment from http://lkml.indiana.edu/hypermail/linux/kernel/1102.1/0041= 2.html: > > "I care about 5K. (But honestly, I don't actively hunt stuff less than > 10K in size, because there's too many of them to chase, currently)." Hm, interesting. Because of, current memory cgroup notification was made by a request from Sony and CELinux. AFAIK, at least, Sony are already using cgroups. >> The fact is, for desktop and server Linux, cgroups slowly becomes a >> mandatory thing. And the reason for this is that cgroups mechanism >> provides some very useful features (in an extensible way, like plugins), >> i.e. a way to manage and track processes and its resources -- which is t= he >> main purpose of cgroups. > > And for embedded and for real-time, some of us do not want cgroups to be > a mandatory thing. =A0We want it to remain configurable. =A0My personal > interest is in keeping the latency of certain critical paths (especially > in the scheduler) short and consistent. As far as I observed, modern embedded system have both RT and no RT process= . Java VM or user downloadable programs may need memory notification because users may download bad programs. in the other hand, rt processes are not downloadable and much tested by hardware vendor. So, I think you only need split process between under cgroups and not under cgroups. cgroups have zero or much likely zero overhead if the processes don't use i= t. Of course, feedback are welcome. I'm interesting your embedded usecase. -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org