From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 4/5] kvm: qemu: Use vringfd to eliminate copies Date: Wed, 18 Jun 2008 07:01:53 -0700 Message-ID: <48591551.4030205@qumranet.com> References: <1213365481-23460-1-git-send-email-markmc@redhat.com> <1213365481-23460-5-git-send-email-markmc@redhat.com> <48545422.1040109@us.ibm.com> <200806161210.57926.rusty@rustcorp.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Anthony Liguori , Mark McLoughlin , kvm@vger.kernel.org To: Rusty Russell Return-path: Received: from il.qumranet.com ([212.179.150.194]:37147 "EHLO il.qumranet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753758AbYFROB5 (ORCPT ); Wed, 18 Jun 2008 10:01:57 -0400 In-Reply-To: <200806161210.57926.rusty@rustcorp.com.au> Sender: kvm-owner@vger.kernel.org List-ID: Rusty Russell wrote: > Yeah, every time I get close to benchmarking I find another bug :( But I've > spent some time optimising the normal lguest net device, so we'll have a fair > comparison. > > In theory vringfd will get us zero copy from guest sendfile out to external > machines. For anything else we're doing a copy anyway, so avoiding copying > has no great benefit. > > The interface is still worthwhile to provide zero-copy receive on intelligent > or bound NICs, but that's science fiction at the moment... > > Eddie is planning exactly this... -- I have a truly marvellous patch that fixes the bug which this signature is too narrow to contain.