From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 676A0C43461 for ; Mon, 14 Sep 2020 11:54:20 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id DD22F21741 for ; Mon, 14 Sep 2020 11:54:19 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DD22F21741 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 52EFE6B005C; Mon, 14 Sep 2020 07:54:19 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 4B97A6B005D; Mon, 14 Sep 2020 07:54:19 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3A7BE6B0062; Mon, 14 Sep 2020 07:54:19 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0111.hostedemail.com [216.40.44.111]) by kanga.kvack.org (Postfix) with ESMTP id 21BBE6B005C for ; Mon, 14 Sep 2020 07:54:19 -0400 (EDT) Received: from smtpin13.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id D6C9318017092 for ; Mon, 14 Sep 2020 11:54:18 +0000 (UTC) X-FDA: 77261508996.13.cloth96_0b1360b27108 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin13.hostedemail.com (Postfix) with ESMTP id A9766180275CE for ; Mon, 14 Sep 2020 11:54:18 +0000 (UTC) X-HE-Tag: cloth96_0b1360b27108 X-Filterd-Recvd-Size: 4334 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf45.hostedemail.com (Postfix) with ESMTP for ; Mon, 14 Sep 2020 11:54:18 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 8160AABF4; Mon, 14 Sep 2020 11:54:32 +0000 (UTC) Date: Mon, 14 Sep 2020 13:54:16 +0200 From: Michal Hocko To: Waiman Long Cc: Johannes Weiner , Vladimir Davydov , Andrew Morton , Tejun Heo , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org, linux-mm@kvack.org, Shakeel Butt , Chris Down , Roman Gushchin , Yafang Shao Subject: Re: [PATCH v2 3/3] mm/memcg: Unify swap and memsw page counters Message-ID: <20200914115416.GN16999@dhcp22.suse.cz> References: <20200914024452.19167-1-longman@redhat.com> <20200914024452.19167-4-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200914024452.19167-4-longman@redhat.com> X-Rspamd-Queue-Id: A9766180275CE X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sun 13-09-20 22:44:52, Waiman Long wrote: > The swap page counter is v2 only while memsw is v1 only. As v1 and v2 > controllers cannot be active at the same time, there is no point to keep > both swap and memsw page counters in mem_cgroup. The previous patch has > made sure that memsw page counter is updated and accessed only when in > v1 code paths. So it is now safe to alias the v1 memsw page counter to v2 > swap page counter. This saves 14 long's in the size of mem_cgroup. This > is a saving of 112 bytes for 64-bit archs. I didn't realize that page_counter is so large. > While at it, also document which page counters are used in v1 and/or v2. > > Signed-off-by: Waiman Long Acked-by: Michal Hocko > --- > include/linux/memcontrol.h | 13 ++++++++----- > mm/memcontrol.c | 3 --- > 2 files changed, 8 insertions(+), 8 deletions(-) > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > index d0b036123c6a..6ef4a552e09d 100644 > --- a/include/linux/memcontrol.h > +++ b/include/linux/memcontrol.h > @@ -215,13 +215,16 @@ struct mem_cgroup { > struct mem_cgroup_id id; > > /* Accounted resources */ > - struct page_counter memory; > - struct page_counter swap; > + struct page_counter memory; /* Both v1 & v2 */ > + > + union { > + struct page_counter swap; /* v2 only */ > + struct page_counter memsw; /* v1 only */ > + }; > > /* Legacy consumer-oriented counters */ > - struct page_counter memsw; > - struct page_counter kmem; > - struct page_counter tcpmem; > + struct page_counter kmem; /* v1 only */ > + struct page_counter tcpmem; /* v1 only */ > > /* Range enforcement for interrupt charges */ > struct work_struct high_work; > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index ca36bed588d1..188901f3a3db 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -5281,13 +5281,11 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css) > memcg->use_hierarchy = true; > page_counter_init(&memcg->memory, &parent->memory); > page_counter_init(&memcg->swap, &parent->swap); > - page_counter_init(&memcg->memsw, &parent->memsw); > page_counter_init(&memcg->kmem, &parent->kmem); > page_counter_init(&memcg->tcpmem, &parent->tcpmem); > } else { > page_counter_init(&memcg->memory, NULL); > page_counter_init(&memcg->swap, NULL); > - page_counter_init(&memcg->memsw, NULL); > page_counter_init(&memcg->kmem, NULL); > page_counter_init(&memcg->tcpmem, NULL); > /* > @@ -5416,7 +5414,6 @@ static void mem_cgroup_css_reset(struct cgroup_subsys_state *css) > > page_counter_set_max(&memcg->memory, PAGE_COUNTER_MAX); > page_counter_set_max(&memcg->swap, PAGE_COUNTER_MAX); > - page_counter_set_max(&memcg->memsw, PAGE_COUNTER_MAX); > page_counter_set_max(&memcg->kmem, PAGE_COUNTER_MAX); > page_counter_set_max(&memcg->tcpmem, PAGE_COUNTER_MAX); > page_counter_set_min(&memcg->memory, 0); > -- > 2.18.1 -- Michal Hocko SUSE Labs