From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752182AbcAZVoZ (ORCPT ); Tue, 26 Jan 2016 16:44:25 -0500 Received: from gum.cmpxchg.org ([85.214.110.215]:54924 "EHLO gum.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751856AbcAZVoW (ORCPT ); Tue, 26 Jan 2016 16:44:22 -0500 Date: Tue, 26 Jan 2016 16:43:34 -0500 From: Johannes Weiner To: Andrew Morton Cc: Vladimir Davydov , Michal Hocko , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: Re: [PATCH] mm: memcontrol: drop superfluous entry in the per-memcg stats array Message-ID: <20160126214334.GA4016@cmpxchg.org> References: <1453841729-29072-1-git-send-email-hannes@cmpxchg.org> <20160126133024.07f372dbf8935e03a3035269@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160126133024.07f372dbf8935e03a3035269@linux-foundation.org> User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 26, 2016 at 01:30:24PM -0800, Andrew Morton wrote: > On Tue, 26 Jan 2016 15:55:29 -0500 Johannes Weiner wrote: > > > MEM_CGROUP_STAT_NSTATS is just a delimiter for cgroup1 statistics, not > > an actual array entry. Reuse it for the first cgroup2 stat entry, like > > in the event array. > > > > ... > > > > --- a/include/linux/memcontrol.h > > +++ b/include/linux/memcontrol.h > > @@ -51,7 +51,7 @@ enum mem_cgroup_stat_index { > > MEM_CGROUP_STAT_SWAP, /* # of pages, swapped out */ > > MEM_CGROUP_STAT_NSTATS, > > /* default hierarchy stats */ > > - MEMCG_SOCK, > > + MEMCG_SOCK = MEM_CGROUP_STAT_NSTATS, > > MEMCG_NR_STAT, > > }; > > The code looks a bit odd. How come mem_cgroup_stat_names[] ends with > "swap"? Should MEMCG_SOCK be in there at all? It's cgroup1 vs. cgroup2 statistics. I'm using the same array in order to use the original statistics infrastructure. It's a little weird, it will be much cleaner once everything is converted to percpu_counter. > And the naming is a bit sad. "MEM_CGROUP_STAT_FILE_MAPPED" maps to > "mapped_file", not "file_mapped". MEM_CGROUP_STAT_FILE_MAPPED is named after NR_FILE_MAPPED because they're both accounted from the same sites. Who knows why the user-visible stat was then called mapped_file... :/ And in cgroup2 it's called file_mapped! At least there it'll be consistent.