From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx156.postini.com [74.125.245.156]) by kanga.kvack.org (Postfix) with SMTP id 26F596B005D for ; Tue, 16 Oct 2012 14:25:08 -0400 (EDT) Date: Tue, 16 Oct 2012 18:25:06 +0000 From: Christoph Lameter Subject: Re: [PATCH v5 14/14] Add documentation about the kmem controller In-Reply-To: <1350382611-20579-15-git-send-email-glommer@parallels.com> Message-ID: <0000013a6ad26c73-d043cf97-c44a-45c1-9cae-0a962e93a005-000000@email.amazonses.com> References: <1350382611-20579-1-git-send-email-glommer@parallels.com> <1350382611-20579-15-git-send-email-glommer@parallels.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Glauber Costa Cc: linux-mm@kvack.org, cgroups@vger.kernel.org, Mel Gorman , Tejun Heo , Andrew Morton , Michal Hocko , Johannes Weiner , kamezawa.hiroyu@jp.fujitsu.com, David Rientjes , Pekka Enberg , devel@openvz.org, linux-kernel@vger.kernel.org, Frederic Weisbecker , Pekka Enberg , Suleiman Souhlal On Tue, 16 Oct 2012, Glauber Costa wrote: > > + memory.kmem.limit_in_bytes # set/show hard limit for kernel memory > + memory.kmem.usage_in_bytes # show current kernel memory allocation > + memory.kmem.failcnt # show the number of kernel memory usage hits limits > + memory.kmem.max_usage_in_bytes # show max kernel memory usage recorded Does it actually make sense to limit kernel memory? The user generally has no idea how much kernel memory a process is using and kernel changes can change the memory footprint. Given the fuzzy accounting in the kernel a large cache refill (if someone configures the slab batch count to be really big f.e.) can account a lot of memory to the wrong cgroup. The allocation could fail. Limiting the total memory use of a process (U+K) would make more sense I guess. Only U is probably sufficient? In what way would a limitation on kernel memory in use be good? -- 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