Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752558AbaKCRai (ORCPT ); Mon, 3 Nov 2014 12:30:38 -0500 Received: from mx2.parallels.com ([199.115.105.18]:55432 "EHLO mx2.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751906AbaKCRaf (ORCPT ); Mon, 3 Nov 2014 12:30:35 -0500 Date: Mon, 3 Nov 2014 20:30:24 +0300 From: Vladimir Davydov To: Johannes Weiner CC: Andrew Morton , Michal Hocko , Tejun Heo , David Miller , , , 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> X-Originating-IP: [81.5.99.36] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: 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 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/