From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark McLoughlin Subject: Re: [PATCH] kvm:virtio-net: Run TX from the I/O thread Date: Thu, 22 Jan 2009 12:48:28 +0000 Message-ID: <1232628508.4533.16.camel@blaa> References: <20090121230642.10404.65372.stgit@kvm.aw> <497862A7.8040408@redhat.com> Reply-To: Mark McLoughlin Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Alex Williamson , kvm@vger.kernel.org To: Avi Kivity Return-path: Received: from mx2.redhat.com ([66.187.237.31]:34965 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755559AbZAVMsc (ORCPT ); Thu, 22 Jan 2009 07:48:32 -0500 In-Reply-To: <497862A7.8040408@redhat.com> Sender: kvm-owner@vger.kernel.org List-ID: On Thu, 2009-01-22 at 14:12 +0200, Avi Kivity wrote: > My worry with this change is that increases cpu utilization even more > than it increases bandwidth, so that our bits/cycle measure decreases. Yep, agreed it's important to watch out for this. > The descriptors (and perhaps data) are likely on the same cache as the > vcpu, and moving the transmit to the iothread will cause them to move to > the iothread's cache. We flush from the I/O thread right now. We only ever flush from the vcpu thread when the ring fills up, which rarely happens from what I've observed. Cheers, Mark.