From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx117.postini.com [74.125.245.117]) by kanga.kvack.org (Postfix) with SMTP id 832BD6B005A for ; Mon, 17 Sep 2012 18:45:52 -0400 (EDT) Message-ID: <5057A80C.3050800@redhat.com> Date: Mon, 17 Sep 2012 18:45:32 -0400 From: Rik van Riel MIME-Version: 1.0 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: owner-linux-mm@kvack.org List-ID: 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" 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 -- 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