From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f180.google.com (mail-pd0-f180.google.com [209.85.192.180]) by kanga.kvack.org (Postfix) with ESMTP id 0F4ED6B0037 for ; Thu, 4 Sep 2014 16:50:39 -0400 (EDT) Received: by mail-pd0-f180.google.com with SMTP id p10so14280600pdj.25 for ; Thu, 04 Sep 2014 13:50:39 -0700 (PDT) Received: from blackbird.sr71.net ([2001:19d0:2:6:209:6bff:fe9a:902]) by mx.google.com with ESMTP id g3si67879pdi.100.2014.09.04.13.50.37 for ; Thu, 04 Sep 2014 13:50:37 -0700 (PDT) Message-ID: <5408D09A.5030000@sr71.net> Date: Thu, 04 Sep 2014 13:50:34 -0700 From: Dave Hansen MIME-Version: 1.0 Subject: Re: regression caused by cgroups optimization in 3.17-rc2 References: <54061505.8020500@sr71.net> <20140902221814.GA18069@cmpxchg.org> <5406466D.1020000@sr71.net> <20140903001009.GA25970@cmpxchg.org> <5406612E.8040802@sr71.net> <20140904150846.GA10794@cmpxchg.org> In-Reply-To: <20140904150846.GA10794@cmpxchg.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Johannes Weiner Cc: Michal Hocko , Hugh Dickins , Tejun Heo , Vladimir Davydov , Linus Torvalds , Andrew Morton , LKML , Linux-MM On 09/04/2014 08:08 AM, Johannes Weiner wrote: > Dave Hansen reports a massive scalability regression in an uncontained > page fault benchmark with more than 30 concurrent threads, which he > bisected down to 05b843012335 ("mm: memcontrol: use root_mem_cgroup > res_counter") and pin-pointed on res_counter spinlock contention. > > That change relied on the per-cpu charge caches to mostly swallow the > res_counter costs, but it's apparent that the caches don't scale yet. > > Revert memcg back to bypassing res_counters on the root level in order > to restore performance for uncontained workloads. A quick sniff test shows performance coming back to what it was around 3.16 with this patch. I'll run a more thorough set of tests and verify that it's working well. -- 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