Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758874AbZAPBao (ORCPT ); Thu, 15 Jan 2009 20:30:44 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753137AbZAPBae (ORCPT ); Thu, 15 Jan 2009 20:30:34 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:49616 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752842AbZAPBad (ORCPT ); Thu, 15 Jan 2009 20:30:33 -0500 Message-ID: <496FE30C.1090300@cn.fujitsu.com> Date: Fri, 16 Jan 2009 09:29:48 +0800 From: Li Zefan User-Agent: Thunderbird 2.0.0.9 (X11/20071115) MIME-Version: 1.0 To: KAMEZAWA Hiroyuki CC: "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "menage@google.com" , "balbir@linux.vnet.ibm.com" , "nishimura@mxp.nes.nec.co.jp" Subject: Re: [PATCH 3/4] memcg: hierarchical reclaim by CSS ID References: <20090115192120.9956911b.kamezawa.hiroyu@jp.fujitsu.com> <20090115192943.7c1df53a.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20090115192943.7c1df53a.kamezawa.hiroyu@jp.fujitsu.com> Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1812 Lines: 54 > /* > - * Dance down the hierarchy if needed to reclaim memory. We remember the > - * last child we reclaimed from, so that we don't end up penalizing > - * one child extensively based on its position in the children list. > + * Visit the first child (need not be the first child as per the ordering > + * of the cgroup list, since we track last_scanned_child) of @mem and use > + * that to reclaim free pages from. > + */ > +static struct mem_cgroup * > +mem_cgroup_select_victim(struct mem_cgroup *root_mem) > +{ > + struct mem_cgroup *ret = NULL; > + struct cgroup_subsys_state *css; > + int nextid, found; > + > + if (!root_mem->use_hierarchy) { > + spin_lock(&root_mem->reclaim_param_lock); > + root_mem->scan_age++; > + spin_unlock(&root_mem->reclaim_param_lock); > + css_get(&root_mem->css); > + ret = root_mem; > + } > + > + while (!ret) { > + rcu_read_lock(); > + nextid = root_mem->last_scanned_child + 1; > + css = css_get_next(&mem_cgroup_subsys, nextid, &root_mem->css, > + &found); > + if (css && css_is_populated(css) && css_tryget(css)) I don't see why you need to check css_is_populated(css) ? > + ret = container_of(css, struct mem_cgroup, css); > + > + rcu_read_unlock(); > + /* Updates scanning parameter */ > + spin_lock(&root_mem->reclaim_param_lock); > + if (!css) { > + /* this means start scan from ID:1 */ > + root_mem->last_scanned_child = 0; > + root_mem->scan_age++; > + } else > + root_mem->last_scanned_child = found; > + spin_unlock(&root_mem->reclaim_param_lock); > + } > + > + return ret; > +} > + -- 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/