From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: Network performance with small packets Date: Thu, 27 Jan 2011 21:31:31 +0200 Message-ID: <20110127193131.GD5228@redhat.com> References: <20110126151700.GA14113@redhat.com> <1296153874.1640.27.camel@localhost.localdomain> <20110127190031.GC5228@redhat.com> <1296155340.1640.34.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Steve Dobbelstein , kvm@vger.kernel.org To: Shirley Ma Return-path: Received: from mx1.redhat.com ([209.132.183.28]:10142 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751423Ab1A0Tbs (ORCPT ); Thu, 27 Jan 2011 14:31:48 -0500 Content-Disposition: inline In-Reply-To: <1296155340.1640.34.camel@localhost.localdomain> Sender: kvm-owner@vger.kernel.org List-ID: On Thu, Jan 27, 2011 at 11:09:00AM -0800, Shirley Ma wrote: > On Thu, 2011-01-27 at 21:00 +0200, Michael S. Tsirkin wrote: > > Interesting. In particular running vhost and the transmitting guest > > on the same host would have the effect of slowing down TX. > > Does it double the BW for you too? > > > > Running vhost and TX guest on the same host seems not good enough to > slow down TX. In order to gain the double even triple BW for guest TX to > local host I still need to play around, so 1K message size, BW is able > to increase from 2.XGb/s to 6.XGb/s. > > Thanks > Shirley Well slowing down the guest does not sound hard - for example we can request guest notifications, or send extra interrupts :) A slightly more sophisticated thing to try is to poll the vq a bit more aggressively. For example if we handled some requests and now tx vq is empty, reschedule and yeild. Worth a try? -- MST