From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932286AbbIYPUb (ORCPT ); Fri, 25 Sep 2015 11:20:31 -0400 Received: from mail-wi0-f172.google.com ([209.85.212.172]:35822 "EHLO mail-wi0-f172.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755260AbbIYPUa (ORCPT ); Fri, 25 Sep 2015 11:20:30 -0400 Date: Fri, 25 Sep 2015 17:20:17 +0200 From: Michal Hocko To: Greg Thelen Cc: Andrew Morton , Johannes Weiner , Cgroups , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH] memcg: make mem_cgroup_read_stat() unsigned Message-ID: <20150925152017.GO16497@dhcp22.suse.cz> References: <20150922210346.749204fb.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed 23-09-15 00:21:33, Greg Thelen wrote: > > Andrew Morton wrote: > > > On Tue, 22 Sep 2015 17:42:13 -0700 Greg Thelen wrote: [...] > >> I assume it's pretty straightforward to create generic > >> percpu_counter_array routines which memcg could use. Possibly something > >> like this could be made general enough could be created to satisfy > >> vmstat, but less clear. > >> > >> [1] http://www.spinics.net/lists/cgroups/msg06216.html > >> [2] https://lkml.org/lkml/2014/9/11/1057 > > > > That all sounds rather bogus to me. __percpu_counter_add() doesn't > > modify struct percpu_counter at all except for when the cpu-local > > counter overflows the configured batch size. And for the memcg > > application I suspect we can set the batch size to INT_MAX... > > Nod. The memory usage will be a bit larger, but the code reuse is > attractive. I dusted off Vladimir's > https://lkml.org/lkml/2014/9/11/710. Next step is to benchmark it > before posting. I am definitely in favor of using generic per-cpu counters. -- Michal Hocko SUSE Labs