From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx114.postini.com [74.125.245.114]) by kanga.kvack.org (Postfix) with SMTP id 4A6D36B0044 for ; Fri, 3 Aug 2012 08:27:35 -0400 (EDT) Date: Fri, 3 Aug 2012 09:26:57 -0300 From: Rafael Aquini Subject: Re: [PATCH v4 1/3] mm: introduce compaction and migration for virtio ballooned pages Message-ID: <20120803122656.GB1848@t510.redhat.com> References: <49f828a9331c9b729fcf77226006921ec5bc52fa.1342485774.git.aquini@redhat.com> <20120718054824.GA32341@bbox> <20120720194858.GA16249@t510.redhat.com> <20120723023332.GA6832@bbox> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120723023332.GA6832@bbox> Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, Rusty Russell , "Michael S. Tsirkin" , Rik van Riel , Mel Gorman , Andi Kleen , Andrew Morton , Konrad Rzeszutek Wilk , Rafael Aquini On Mon, Jul 23, 2012 at 11:33:32AM +0900, Minchan Kim wrote: > Look at memory-hotplug, offline_page calls has_unmovable_pages, scan_lru_pages > and do_migrate_range which calls isolate_lru_page. They consider only LRU pages > to migratable ones. > As promised, I looked into those bits. Yes, they only isolate LRU pages, and as such, having this series merged or not doesn't change a bit for that code path. In fact, having this series merged and teaching hotplug's offline_pages()/do_migrate_rage() about ballooned pages might be extremely beneficial in the rare event offlining memory stumbles across a balloon page. As Rik said, I believe this is something we can look into in the near future. > IMHO, better approach is that after we can get complete free pageblocks > by compaction or reclaim, move balloon pages into that pageblocks and make > that blocks to unmovable. It can prevent fragmentation and it makes > current or future code don't need to consider balloon page. > I totally agree with Rik on this one, as well. This is the wrong approach here. All that said, I'll soon respin a v5 based on your comments on branch hinting and commentary improvements, as well as addressing AKPM's concerns. I'll also revert isolate_balloon_page() last changes back to make it a public symbol again, as (I believe) we'll shortly be using it for letting hotplug bits aware of how to isolate ballooned pages. -- 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