From mboxrd@z Thu Jan 1 00:00:00 1970 From: Anthony Liguori Subject: Re: [PATCH] virtio_net tx performance fix Date: Mon, 28 Jan 2008 22:09:48 -0600 Message-ID: <479EA70C.1080108@us.ibm.com> References: <1201479224.3047.37.camel@localhost.localdomain> <479DF5A8.8050103@us.ibm.com> <1201535954.2457.11.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1201535954.2457.11.camel@localhost.localdomain> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: dor.laor@qumranet.com Cc: kvm-devel , "virtualization@lists.linux-foundation.org" List-Id: virtualization@lists.linuxfoundation.org Dor Laor wrote: > On Mon, 2008-01-28 at 09:32 -0600, Anthony Liguori wrote: > >> Hi Dor, >> >> How are you measuring performance? The numbers I've gotten with netperf >> before and after your patch are: >> >> tx - 647.27mbit >> rx - 89.22 >> >> tx - 27.82 >> rx - 79.93 >> >> > > I've been testing with iperf (patched with Ingo's fix). > I also tested tcp/udp (udp tx is only 550Mbps with the patch, w/o it's > only 220Mbps) > FWIW, I repeated with an scp test copying a 200mb file from /dev/shm on the host to the guest and vice versa. rx performance is around 3-4 MB/sec. Without your patch, tx performance is around 40 MB/sec whereas with your patch performance is around 30 MB/sec. So the tx drop is definitely exaggerated by netperf. I'm definitely not seeing an increase in throughput though. Could you try a similar scp test? What sort of networking setup are you using? My guest kernel and host kernel are both 2.6.24 (from Ubuntu Hardy). Regards, Anthony Liguori