From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: vhost net: performance with ping benchmark Date: Tue, 25 Aug 2009 08:24:07 -0500 Message-ID: <4A93E5F7.5010606@codemonkey.ws> References: <20090824081240.GA3415@redhat.com> <20090824212137.GA9835@redhat.com> <4A934AF7.2090904@codemonkey.ws> <4A936525.5030300@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: "Michael S. Tsirkin" , virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, Rusty Russell , Mark McLoughlin To: Avi Kivity Return-path: Received: from qw-out-2122.google.com ([74.125.92.24]:26073 "EHLO qw-out-2122.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751563AbZHYNYT (ORCPT ); Tue, 25 Aug 2009 09:24:19 -0400 Received: by qw-out-2122.google.com with SMTP id 8so1663510qwh.37 for ; Tue, 25 Aug 2009 06:24:21 -0700 (PDT) In-Reply-To: <4A936525.5030300@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: Avi Kivity wrote: > My preference is ring proxying. Not we'll need ring proxying (or at > least event proxying) for non-MSI guests. Thinking about this more... How does the hand off work? Assuming you normally don't proxy ring entries and switch to proxying them when you want to migration, do you have a set of ioctl()s that changes the semantics of the ring to be host virtual addresses instead of guest physical? If so, what do you do with in flight requests? Does qemu have to buffer new requests and wait for old ones to complete? Unless you always do ring proxying. If that's the case, we don't need any of the slot management code in vhost. Regards, Anthony Liguori