From mboxrd@z Thu Jan 1 00:00:00 1970 From: Glauber Costa Subject: Re: [PATCH 00/11] kmem controller for memcg: stripped down version Date: Wed, 27 Jun 2012 12:39:54 +0400 Message-ID: <4FEAC6DA.1010806@parallels.com> References: <1340633728-12785-1-git-send-email-glommer@parallels.com> <20120625162745.eabe4f03.akpm@linux-foundation.org> <4FE9621D.2050002@parallels.com> <20120626145539.eeeab909.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: David Rientjes Cc: Andrew Morton , cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Frederic Weisbecker , Pekka Enberg , Michal Hocko , Johannes Weiner , Christoph Lameter , devel-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org, kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org, Tejun Heo On 06/27/2012 05:08 AM, David Rientjes wrote: > On Tue, 26 Jun 2012, Andrew Morton wrote: > >> mm, maybe. Kernel developers tend to look at code from the point of >> view "does it work as designed", "is it clean", "is it efficient", "do >> I understand it", etc. We often forget to step back and really >> consider whether or not it should be merged at all. >> > > It's appropriate for true memory isolation so that applications cannot > cause an excess of slab to be consumed. This allows other applications to > have higher reservations without the risk of incurring a global oom > condition as the result of the usage of other memcgs. Just a note for Andrew, we we're in the same page: The slab cache limitation is not included in *this* particular series. The goal was always to have other kernel resources limited as well, and the general argument from David holds: we want a set of applications to run truly independently from others, without creating memory pressure on the global system. The way history develop in this series, I started from the slab cache, and a page-level tracking appeared on that series. I then figured it would be better to start tracking something that is totally page-based, such as the stack - that already accounts for 70 % of the infrastructure, and then merge the slab code later. In this sense, it was just a strategy inversion. But both are, and were, in the goals. > I'm not sure whether it would ever be appropriate to limit the amount of > slab for an individual slab cache, however, instead of limiting the sum of > all slab for a set of processes. With cache merging in slub this would > seem to be difficult to do correctly. Yes, I do agree.