From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx183.postini.com [74.125.245.183]) by kanga.kvack.org (Postfix) with SMTP id 3766A6B0069 for ; Wed, 22 Aug 2012 04:26:14 -0400 (EDT) Message-ID: <503496D9.3020806@parallels.com> Date: Wed, 22 Aug 2012 12:22:49 +0400 From: Glauber Costa MIME-Version: 1.0 Subject: Re: [PATCH v2 09/11] memcg: propagate kmem limiting information to children References: <1344517279-30646-1-git-send-email-glommer@parallels.com> <1344517279-30646-10-git-send-email-glommer@parallels.com> <20120817090005.GC18600@dhcp22.suse.cz> <502E0BC3.8090204@parallels.com> <20120817093504.GE18600@dhcp22.suse.cz> <502E17C4.7060204@parallels.com> <20120817103550.GF18600@dhcp22.suse.cz> <502E1E90.1080805@parallels.com> <20120821075430.GA19797@dhcp22.suse.cz> <50335341.6010400@parallels.com> <20120821100007.GE19797@dhcp22.suse.cz> In-Reply-To: Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Greg Thelen Cc: Michal Hocko , linux-kernel@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org, devel@openvz.org, Johannes Weiner , Andrew Morton , kamezawa.hiroyu@jp.fujitsu.com, Christoph Lameter , David Rientjes , Pekka Enberg , Pekka Enberg , Suleiman Souhlal >>> >>> I am fine with either, I just need a clear sign from you guys so I don't >>> keep deimplementing and reimplementing this forever. >> >> I would be for make it simple now and go with additional features later >> when there is a demand for them. Maybe we will have runtimg switch for >> user memory accounting as well one day. >> >> But let's see what others think? > > In my use case memcg will either be disable or (enabled and kmem > limiting enabled). > > I'm not sure I follow the discussion about history. Are we saying that > once a kmem limit is set then kmem will be accounted/charged to memcg. > Is this discussion about the static branches/etc that are autotuned the > first time is enabled? No, the question is about when you unlimit a former kmem-limited memcg. > The first time its set there parts of the system > will be adjusted in such a way that may impose a performance overhead > (static branches, etc). Thereafter the performance cannot be regained > without a reboot. This makes sense to me. Are we saying that > kmem.limit_in_bytes will have three states? It is not about performance, about interface. Michal says that once a particular memcg was kmem-limited, it will keep accounting pages, even if you make it unlimited. The limits won't be enforced, for sure - there is no limit, but pages will still be accounted. This simplifies the code galore, but I worry about the interface: A person looking at the current status of the files only, without knowledge of past history, can't tell if allocations will be tracked or not. -- 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