From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH] KVM simplified virtio balloon driver Date: Sat, 19 Jan 2008 09:02:29 +0200 Message-ID: <4791A085.8060502@qumranet.com> References: <20080114200357.GA18354@dmt> <20080115190102.GA27645@dmt> <1200525166.26281.103.camel@localhost.localdomain> <200801171245.59510.rusty@rustcorp.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: Marcelo Tosatti , kvm-devel , virtualization-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Rusty Russell Return-path: In-Reply-To: <200801171245.59510.rusty-8n+1lVoiYb80n/F98K4Iww@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org Errors-To: kvm-devel-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: kvm.vger.kernel.org Rusty Russell wrote: > After discussions with Anthony Liguori, it seems that the virtio > balloon can be made even simpler. Here's my attempt. > > Since the balloon requires Guest cooperation anyway, there seems > little reason to force it to tell the Host when it wants to reuse a > page. It can simply fault it in. > > Faulting is synchronous, while deflating is (or can be made) asynchronous. If the host needs to do some work to get the memory, the guest will be slowed down considerably. If we have explicit deflate, the host can call madvise(MADV_WILLNEED) or actually touch the pages before the guest accesses them. -- Any sufficiently difficult bug is indistinguishable from a feature. ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/