Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754988Ab2FZXpm (ORCPT ); Tue, 26 Jun 2012 19:45:42 -0400 Received: from mail-wg0-f44.google.com ([74.125.82.44]:40480 "EHLO mail-wg0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754368Ab2FZXpi convert rfc822-to-8bit (ORCPT ); Tue, 26 Jun 2012 19:45:38 -0400 MIME-Version: 1.0 In-Reply-To: <4FEA2D85.60002@redhat.com> References: <1340742778-11282-1-git-send-email-fes@google.com> <4FEA1E2E.4020806@redhat.com> <4FEA2D85.60002@redhat.com> Date: Tue, 26 Jun 2012 16:45:36 -0700 Message-ID: Subject: Re: [PATCH] Add a page cache-backed balloon device driver. From: Frank Swiderski To: Rik van Riel Cc: Rusty Russell , "Michael S. Tsirkin" , Andrea Arcangeli , virtualization@lists.linux-foundation.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, mikew@google.com, Ying Han , Rafael Aquini Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2061 Lines: 55 On Tue, Jun 26, 2012 at 2:45 PM, Rik van Riel wrote: > On 06/26/2012 05:31 PM, Frank Swiderski wrote: >> >> On Tue, Jun 26, 2012 at 1:40 PM, Rik van Riel ?wrote: > > >>> The code looks good to me, my only worry is the >>> code duplication. We now have 5 balloon drivers, >>> for 4 hypervisors, all implementing everything >>> from scratch... >> >> >> Do you have any recommendations on this? ?I could (I think reasonably >> so) modify the existing virtio_balloon.c and have it change behavior >> based on a feature bit or other configuration. ?I'm not sure that >> really addresses the root of what you're pointing out--it's still >> adding a different implementation, but doing so as an extension of an >> existing one. > > > Ideally, I believe we would have two balloon > top parts in a guest (one classical balloon, > one on the LRU), and four bottom parts (kvm, > xen, vmware & s390). > > That way the virt specific bits of a balloon > driver would be essentially a ->balloon_page > and ->release_page callback for pages, as well > as methods to communicate with the host. > > All the management of pages, including stuff > like putting them on the LRU, or isolating > them for migration, would be done with the > same common code, regardless of what virt > software we are running on. > > Of course, that is a substantial amount of > work and I feel it would be unreasonable to > block anyone's code on that kind of thing > (especially considering that your code is good), > but I do believe the explosion of balloon > code is a little worrying. > Hm, that makes a lot of sense. That would be a few patches definitely worth doing, IMHO. I'm not entirely sure how I feel about inflating the balloon drivers in the meantime. Sigh, and I didn't even mean that as a pun. fes -- 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/