From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f177.google.com (mail-pd0-f177.google.com [209.85.192.177]) by kanga.kvack.org (Postfix) with ESMTP id 6EFD46B00FE for ; Mon, 3 Nov 2014 12:30:36 -0500 (EST) Received: by mail-pd0-f177.google.com with SMTP id v10so11772634pde.22 for ; Mon, 03 Nov 2014 09:30:36 -0800 (PST) Received: from mx2.parallels.com (mx2.parallels.com. [199.115.105.18]) by mx.google.com with ESMTPS id xk1si15794171pab.121.2014.11.03.09.30.34 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 03 Nov 2014 09:30:35 -0800 (PST) Date: Mon, 3 Nov 2014 20:30:24 +0300 From: Vladimir Davydov Subject: Re: [patch 1/3] mm: embed the memcg pointer directly into struct page Message-ID: <20141103173024.GU17258@esperanza> References: <1414898156-4741-1-git-send-email-hannes@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <1414898156-4741-1-git-send-email-hannes@cmpxchg.org> Sender: owner-linux-mm@kvack.org List-ID: To: Johannes Weiner Cc: Andrew Morton , Michal Hocko , Tejun Heo , David Miller , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org On Sat, Nov 01, 2014 at 11:15:54PM -0400, Johannes Weiner wrote: > Memory cgroups used to have 5 per-page pointers. To allow users to > disable that amount of overhead during runtime, those pointers were > allocated in a separate array, with a translation layer between them > and struct page. > > There is now only one page pointer remaining: the memcg pointer, that > indicates which cgroup the page is associated with when charged. The > complexity of runtime allocation and the runtime translation overhead > is no longer justified to save that *potential* 0.19% of memory. With > CONFIG_SLUB, page->mem_cgroup actually sits in the doubleword padding > after the page->private member and doesn't even increase struct page, > and then this patch actually saves space. Remaining users that care > can still compile their kernels without CONFIG_MEMCG. > > text data bss dec hex filename > 8828345 1725264 983040 11536649 b00909 vmlinux.old > 8827425 1725264 966656 11519345 afc571 vmlinux.new > > Signed-off-by: Johannes Weiner Acked-by: Vladimir Davydov -- 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