Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754728AbZDBL74 (ORCPT ); Thu, 2 Apr 2009 07:59:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751602AbZDBL7m (ORCPT ); Thu, 2 Apr 2009 07:59:42 -0400 Received: from mx2.redhat.com ([66.187.237.31]:56609 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751062AbZDBL7l (ORCPT ); Thu, 2 Apr 2009 07:59:41 -0400 Message-ID: <49D4A89E.5090407@redhat.com> Date: Thu, 02 Apr 2009 14:59:26 +0300 From: Avi Kivity User-Agent: Thunderbird 2.0.0.21 (X11/20090320) MIME-Version: 1.0 To: Gregory Haskins CC: Herbert Xu , anthony@codemonkey.ws, andi@firstfloor.org, linux-kernel@vger.kernel.org, agraf@suse.de, pmullaney@novell.com, pmorreale@novell.com, rusty@rustcorp.com.au, netdev@vger.kernel.org, kvm@vger.kernel.org, Mark McLoughlin Subject: Re: [RFC PATCH 00/17] virtual-bus References: <20090402085253.GA29932@gondor.apana.org.au> <49D47F11.6070400@redhat.com> <20090402091639.GA30126@gondor.apana.org.au> <49D484F5.2000400@redhat.com> <20090402092936.GA30333@gondor.apana.org.au> <49D487A6.407@redhat.com> <49D49C1F.6030306@novell.com> In-Reply-To: <49D49C1F.6030306@novell.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1262 Lines: 36 Gregory Haskins wrote: >> Why does a kernel solution not need to know when a packet is transmitted? >> >> > > You do not need to know when the packet is copied (which I currently > do). You only need it for zero-copy (of which I would like to support, > but as I understand it there are problems with the reliability of proper > callback (i.e. skb->destructor). > > Its "fire and forget" :) > It's more of a "schedule and forget" which I think brings you the win. The host disables notifications and schedules the actual tx work (rx from the host's perspective). So now the guest and host continue producing and consuming packets in parallel. So long as the guest is faster (due to the host being throttled?), notifications continue to be disabled. If you changed your rx_isr() to process the packets immediately instead of scheduling, I think throughput would drop dramatically. Mark had a similar change for virtio. Mark? -- error compiling committee.c: too many arguments to function -- 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/