From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx164.postini.com [74.125.245.164]) by kanga.kvack.org (Postfix) with SMTP id 7FAE46B005C for ; Mon, 9 Jan 2012 03:29:00 -0500 (EST) From: Subject: RE: [PATCH 3.2.0-rc1 0/3] Used Memory Meter pseudo-device and related changes in MM Date: Mon, 9 Jan 2012 08:27:52 +0000 Message-ID: <84FF21A720B0874AA94B46D76DB98269045549DF@008-AM1MPN1-003.mgdnok.nokia.com> References: <20120104195612.GB19181@suse.de> <84FF21A720B0874AA94B46D76DB98269045542B5@008-AM1MPN1-003.mgdnok.nokia.com> <84FF21A720B0874AA94B46D76DB9826904554391@008-AM1MPN1-003.mgdnok.nokia.com> <20120105145753.GA3937@suse.de> <84FF21A720B0874AA94B46D76DB98269045545E5@008-AM1MPN1-003.mgdnok.nokia.com> In-Reply-To: Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: rientjes@google.com Cc: gregkh@suse.de, penberg@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, cesarb@cesarb.net, kamezawa.hiroyu@jp.fujitsu.com, emunson@mgebm.net, aarcange@redhat.com, riel@redhat.com, mel@csn.ul.ie, dima@android.com, rebecca@android.com, san@google.com, akpm@linux-foundation.org, vesa.jaaskelainen@nokia.com > -----Original Message----- > From: ext David Rientjes [mailto:rientjes@google.com] > Sent: 06 January, 2012 01:10 > If you can accept the overhead of the memory controller (increase in > kernel text size and amount of metadata for page_cgroup), then you can > already do this with a combination of memory thresholds with > cgroup.event_control and disabling of the oom killer entirely with > memory.oom_control. You can also get notified when the oom killer is > triggered by using eventfd(2) on memory.oom_control even though it's > disabled in the kernel. Then, the userspace task attached to that contro= l > file can send signals to applications to free their memory or, in the > worst case, choose to kill an application but have all that policy be > implemented in userspace. We invested in memcg notification (Kiryl Shutsemau's patches) and use the s= imilar approach in n9 already (see libmemnotifyqt on gitorious). Unfortunately it is produces number of side effects which are related how m= emcg handled application injection/removal from/to group. So I like to try another approach. > We actually have extended that internally to have an oom killer delay, > i.e. a specific amount of time must pass for userspace to react to the oo= m ... > handled the event"). Those patches were posted on linux-mm several > months > ago but never merged upstream. You should be able to use the same > concept > apart from the memory controller and implement it generically. Yep. But in n9 concept OOMing some application is acceptable, so I do not s= ee such changes as very suitable. > You also presented this as an alternative for "embedded or small" users s= o > I wasn't aware that using the memory controller was an acceptable solutio= n > given its overhead. Overhead, by the way, fully acceptable and I think in never kernels (3.x) s= ituation will be much better. But memcg has from my point principal problems for case when you cgroup app= lication set is updated when application foregrounded/backgrounded, unfortu= nately that is how n900 and n9 software designed. Best Wishes, Leonid -- 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