Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754004AbbGPHTx (ORCPT ); Thu, 16 Jul 2015 03:19:53 -0400 Received: from mail-wi0-f174.google.com ([209.85.212.174]:33001 "EHLO mail-wi0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752124AbbGPHTw (ORCPT ); Thu, 16 Jul 2015 03:19:52 -0400 Date: Thu, 16 Jul 2015 09:19:49 +0200 From: Michal Hocko To: Andrew Morton Cc: Johannes Weiner , Vladimir Davydov , Tejun Heo , linux-mm@kvack.org, LKML Subject: Re: [PATCH 1/5] memcg: export struct mem_cgroup Message-ID: <20150716071948.GC3077@dhcp22.suse.cz> References: <1436958885-18754-1-git-send-email-mhocko@kernel.org> <1436958885-18754-2-git-send-email-mhocko@kernel.org> <20150715135711.1778a8c08f2ea9560a7c1f6f@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150715135711.1778a8c08f2ea9560a7c1f6f@linux-foundation.org> 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 Content-Length: 2475 Lines: 61 On Wed 15-07-15 13:57:11, Andrew Morton wrote: > On Wed, 15 Jul 2015 13:14:41 +0200 Michal Hocko wrote: > > > mem_cgroup structure is defined in mm/memcontrol.c currently which > > means that the code outside of this file has to use external API even > > for trivial access stuff. > > > > This patch exports mm_struct with its dependencies and makes some of the > > exported functions inlines. This even helps to reduce the code size a bit > > (make defconfig + CONFIG_MEMCG=y) > > > > text data bss dec hex filename > > 12355346 1823792 1089536 15268674 e8fb42 vmlinux.before > > 12354970 1823792 1089536 15268298 e8f9ca vmlinux.after > > > > This is not much (370B) but better than nothing. We also save a function > > call in some hot paths like callers of mem_cgroup_count_vm_event which is > > used for accounting. > > > > The patch doesn't introduce any functional changes. > > > > ... > > > > include/linux/memcontrol.h | 369 +++++++++++++++++++++++++++++++++++++++++---- > > Boy, that's a ton of new stuff into the header file. Do we actually > *need* to expose all this? I am exporting struct mem_cgroup with its dependencies + some small functions which allow to inline some really trivial code and helps to generate a better code. > Is some other patch dependent on it? Without mem_cgroup visible outside of memcontrol.c we couldn't inline and now we can also use some fields from mem_cgroup directly and get rid of some really trivial access functions. > If > not then perhaps we shouldn't do this - if the code was already this > way, I'd be attracted to a patch which was the reverse of this one! I agree with Johannes who originally suggested to expose mem_cgroup that it will allow for a better code later. > There's some risk of build breakage here - just from a quick scan, > memcontrol.h is going to need eventfd.h for eventfd_ctx. But what else > is needed? I have tested this with all{mod,yes,no}config + my battery of configs which I am using for mm git tree testing + some randconfig without issues. Sure there might be some config combo I haven't tested but I guess it should be quite unlikely. -- Michal Hocko SUSE Labs -- 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/