From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx166.postini.com [74.125.245.166]) by kanga.kvack.org (Postfix) with SMTP id 6CFB76B0044 for ; Tue, 14 Aug 2012 07:04:03 -0400 (EDT) Message-ID: <502A2FE5.4060809@parallels.com> Date: Tue, 14 Aug 2012 15:00:53 +0400 From: Glauber Costa MIME-Version: 1.0 Subject: Re: [PATCH v2 06/11] memcg: kmem controller infrastructure References: <1344517279-30646-1-git-send-email-glommer@parallels.com> <1344517279-30646-7-git-send-email-glommer@parallels.com> <50254475.4000201@jp.fujitsu.com> In-Reply-To: <50254475.4000201@jp.fujitsu.com> Content-Type: text/plain; charset="ISO-2022-JP" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Kamezawa Hiroyuki Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, cgroups@vger.kernel.org, devel@openvz.org, Michal Hocko , Johannes Weiner , Andrew Morton , Christoph Lameter , David Rientjes , Pekka Enberg , Pekka Enberg On 08/10/2012 09:27 PM, Kamezawa Hiroyuki wrote: >> +bool __memcg_kmem_new_page(gfp_t gfp, void *_handle, int order) >> > +{ >> > + struct mem_cgroup *memcg; >> > + struct mem_cgroup **handle = (struct mem_cgroup **)_handle; >> > + bool ret = true; >> > + size_t size; >> > + struct task_struct *p; >> > + >> > + *handle = NULL; >> > + rcu_read_lock(); >> > + p = rcu_dereference(current->mm->owner); >> > + memcg = mem_cgroup_from_task(p); >> > + if (!memcg_kmem_enabled(memcg)) >> > + goto out; >> > + >> > + mem_cgroup_get(memcg); >> > + > This mem_cgroup_get() will be a potentioal performance problem. > Don't you have good idea to avoid accessing atomic counter here ? > I think some kind of percpu counter or a feature to disable "move task" > will be a help. > > I have just sent out a proposal to deal with this. I tried the trick of marking only the first charge and last uncharge, and it works quite alright at the cost of a bit test on most calls to memcg_kmem_charge. Please let me know what you think. -- 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