From mboxrd@z Thu Jan 1 00:00:00 1970 From: Glauber Costa Subject: [RFC 4/4] memcg: do not walk all the way to the root for memcg Date: Tue, 25 Sep 2012 12:52:53 +0400 Message-ID: <1348563173-8952-5-git-send-email-glommer@parallels.com> References: <1348563173-8952-1-git-send-email-glommer@parallels.com> Return-path: In-Reply-To: <1348563173-8952-1-git-send-email-glommer-bzQdu9zFT3WakBO8gow8eQ@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, devel-GEFAQzZX7r8dnm+yROfE0A@public.gmane.org, Peter Zijlstra , Glauber Costa , Michal Hocko , Kamezawa Hiroyuki , Johannes Weiner , Mel Gorman , Andrew Morton Since the root is special anyway, and we always get its figures from global counters anyway, there is no make all cgroups its descendants, wrt res_counters. The sad effect of doing that is that we need to lock the root for all allocations, since it is a common ancestor of everybody. Not having the root as a common ancestor should lead to better scalability for not-uncommon case of tasks in the cgroup being node-bound to different nodes in NUMA systems. Signed-off-by: Glauber Costa CC: Michal Hocko CC: Kamezawa Hiroyuki CC: Johannes Weiner CC: Mel Gorman CC: Andrew Morton --- mm/memcontrol.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index f8115f0..829ea9e 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -5720,7 +5720,7 @@ mem_cgroup_create(struct cgroup *cont) static_key_slow_inc(&memcg_in_use_key); } - if (parent && parent->use_hierarchy) { + if (parent && !mem_cgroup_is_root(parent) && parent->use_hierarchy) { struct mem_cgroup __maybe_unused *p; res_counter_init(&memcg->res, &parent->res); -- 1.7.11.4