From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757443Ab2IQWqE (ORCPT ); Mon, 17 Sep 2012 18:46:04 -0400 Received: from mx1.redhat.com ([209.132.183.28]:31856 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757415Ab2IQWqA (ORCPT ); Mon, 17 Sep 2012 18:46:00 -0400 Message-ID: <5057A80C.3050800@redhat.com> Date: Mon, 17 Sep 2012 18:45:32 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120827 Thunderbird/15.0 MIME-Version: 1.0 To: Andrew Morton CC: Rafael Aquini , linux-mm@kvack.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Rusty Russell , "Michael S. Tsirkin" , Mel Gorman , Andi Kleen , Konrad Rzeszutek Wilk , Minchan Kim , Peter Zijlstra , "Paul E. McKenney" Subject: Re: [PATCH v10 0/5] make balloon pages movable by compaction References: <20120917151531.e9ac59f2.akpm@linux-foundation.org> In-Reply-To: <20120917151531.e9ac59f2.akpm@linux-foundation.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/17/2012 06:15 PM, Andrew Morton wrote: > On Mon, 17 Sep 2012 13:38:15 -0300 > Rafael Aquini wrote: > >> Memory fragmentation introduced by ballooning might reduce significantly >> the number of 2MB contiguous memory blocks that can be used within a guest, >> thus imposing performance penalties associated with the reduced number of >> transparent huge pages that could be used by the guest workload. >> >> This patch-set follows the main idea discussed at 2012 LSFMMS session: >> "Ballooning for transparent huge pages" -- http://lwn.net/Articles/490114/ >> to introduce the required changes to the virtio_balloon driver, as well as >> the changes to the core compaction & migration bits, in order to make those >> subsystems aware of ballooned pages and allow memory balloon pages become >> movable within a guest, thus avoiding the aforementioned fragmentation issue >> >> Following are numbers that prove this patch benefits on allowing compaction >> to be more effective at memory ballooned guests. >> >> Results for STRESS-HIGHALLOC benchmark, from Mel Gorman's mmtests suite, >> running on a 4gB RAM KVM guest which was ballooning 1gB RAM in 256mB chunks, >> at every minute (inflating/deflating), while test was running: > > How can a patchset reach v10 and have zero Reviewed-by's? Because people kept finding issues and nitpicks in patch 1/5, which kept people from putting their Reviewed-by's on the other patches :) > (The question of "overall desirability" is the big one here. Do we > actually want to add this to Linux? The rest is details which we can > work out). I believe we absolutely want this, to increase the likelyhood of being able to use THP in KVM guests, which is exactly where THP gives the largest performance benefit. -- All rights reversed