From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id 2CCD26B0092 for ; Thu, 13 Jan 2011 07:24:11 -0500 (EST) Received: by iyj17 with SMTP id 17so1508465iyj.14 for ; Thu, 13 Jan 2011 04:24:09 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20110113030415.GF2897@balbir.in.ibm.com> References: <20110113105741.dd38d58e.nishimura@mxp.nes.nec.co.jp> <20110113030415.GF2897@balbir.in.ibm.com> Date: Thu, 13 Jan 2011 15:24:09 +0300 Message-ID: Subject: Re: cgroups and overcommit question From: Evgeniy Ivanov Content-Type: text/plain; charset=ISO-8859-1 Sender: owner-linux-mm@kvack.org To: balbir@linux.vnet.ibm.com Cc: Daisuke Nishimura , linux-mm , KAMEZAWA Hiroyuki List-ID: On Thu, Jan 13, 2011 at 6:04 AM, Balbir Singh wrote: > * nishimura@mxp.nes.nec.co.jp [2011-01-13 10:57:41]: > >> Hi. >> >> On Wed, 12 Jan 2011 18:40:37 +0300 >> Evgeniy Ivanov wrote: >> >> > Hello, >> > >> > When I forbid memory overcommiting, malloc() returns 0 if can't >> > reserve memory, but in a cgroup it will always succeed, when it can >> > succeed when not in the group. >> > E.g. I've set 2 to overcommit_memory, limit is 10M: I can ask malloc >> > 100M and it will not return any error (kernel is 2.6.32). >> > Is it expected behavior? >> > >> Yes. Because memory cgroup can be used for limiting the memory(and swap) size >> which is physically used, not the malloc'ed size. Yeah, I see. But it doesn't seem complicated/expensive to check (already_charged + malloc_requested) and charge new pages if overcommit disabled. man 5 proc says about vm/overcommit_memory "2: always check, never overcommit". So there should be either a note or malloc within cgroup should be consistent with other part of the system. > I had rlimit based cgroup to limit virtual memory size, but the > patches were never merged due to lack of use cases :( > > See http://lwn.net/Articles/283287/ > > I did advocate as use case the ability to prevent overcommit. I > suspect another way of solving this problem is to have overcommit > control. The problem today is that OOM is our backup to overcommit, > not a very comfortable feeling. I fully agree with you. -- Evgeniy Ivanov -- 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 policy in Canada: sign http://dissolvethecrtc.ca/ Don't email: email@kvack.org