From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx163.postini.com [74.125.245.163]) by kanga.kvack.org (Postfix) with SMTP id 3A8B56B005D for ; Wed, 30 May 2012 04:25:28 -0400 (EDT) Received: by qcsd16 with SMTP id d16so3229635qcs.14 for ; Wed, 30 May 2012 01:25:27 -0700 (PDT) Message-ID: <4FC5D973.3080108@gmail.com> Date: Wed, 30 May 2012 04:25:23 -0400 From: KOSAKI Motohiro MIME-Version: 1.0 Subject: Re: [PATCH 13/35] autonuma: add page structure fields References: <1337965359-29725-1-git-send-email-aarcange@redhat.com> <1337965359-29725-14-git-send-email-aarcange@redhat.com> <1338297385.26856.74.camel@twins> <4FC4D58A.50800@redhat.com> <1338303251.26856.94.camel@twins> In-Reply-To: <1338303251.26856.94.camel@twins> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra Cc: Rik van Riel , Andrea Arcangeli , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Hillf Danton , Dan Smith , Linus Torvalds , Andrew Morton , Thomas Gleixner , Ingo Molnar , Paul Turner , Suresh Siddha , Mike Galbraith , "Paul E. McKenney" , Lai Jiangshan , Bharata B Rao , Lee Schermerhorn , Johannes Weiner , Srivatsa Vaddagiri , Christoph Lameter , kosaki.motohiro@gmail.com (5/29/12 10:54 AM), Peter Zijlstra wrote: > On Tue, 2012-05-29 at 09:56 -0400, Rik van Riel wrote: >> On 05/29/2012 09:16 AM, Peter Zijlstra wrote: >>> On Fri, 2012-05-25 at 19:02 +0200, Andrea Arcangeli wrote: >> >>> 24 bytes per page.. or ~0.6% of memory gone. This is far too great a >>> price to pay. >>> >>> At LSF/MM Rik already suggested you limit the number of pages that can >>> be migrated concurrently and use this to move the extra list_head out of >>> struct page and into a smaller amount of extra structures, reducing the >>> total overhead. >> >> For THP, we should be able to track this NUMA info on a >> 2MB page granularity. > > Yeah, but that's another x86-only feature, _IF_ we're going to do this > it must be done for all archs that have CONFIG_NUMA, thus we're stuck > with 4k (or other base page size). Even if THP=n, we don't need 4k granularity. All modern malloc implementation have per-thread heap (e.g. glibc call it as arena) and it is usually 1-8MB size. So, if it is larger than 2MB, we can always use per-pmd tracking. iow, memory consumption reduce to 1/512. My suggestion is, track per-pmd (i.e. 2M size) granularity and fix glibc too (current glibc malloc has dynamically arena size adjusting feature and then it often become less than 2M). -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org