Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754055Ab2HVI0N (ORCPT ); Wed, 22 Aug 2012 04:26:13 -0400 Received: from mx2.parallels.com ([64.131.90.16]:56090 "EHLO mx2.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751312Ab2HVI0I (ORCPT ); Wed, 22 Aug 2012 04:26:08 -0400 Message-ID: <503496D9.3020806@parallels.com> Date: Wed, 22 Aug 2012 12:22:49 +0400 From: Glauber Costa User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:14.0) Gecko/20120717 Thunderbird/14.0 MIME-Version: 1.0 To: Greg Thelen CC: Michal Hocko , , , , , Johannes Weiner , Andrew Morton , , Christoph Lameter , David Rientjes , Pekka Enberg , Pekka Enberg , Suleiman Souhlal 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: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1816 Lines: 42 >>> >>> 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 from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/