From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fabian Deutsch Subject: Re: Network poblems using virtio and tap. Date: Fri, 05 Sep 2008 13:47:29 +0200 Message-ID: <1220615249.2898.8.camel@decade.local> References: <20080901124245.96790@gmx.net> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit To: kvm@vger.kernel.org Return-path: Received: from mail.gmx.net ([213.165.64.20]:56267 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751325AbYIELre (ORCPT ); Fri, 5 Sep 2008 07:47:34 -0400 In-Reply-To: <20080901124245.96790@gmx.net> Sender: kvm-owner@vger.kernel.org List-ID: Hello. It seems to be a problem of virtio. Using e1000 again, I don't get into trouble anymore. - fabian Am Montag, den 01.09.2008, 14:42 +0200 schrieb Fabian Deutsch: > Hey. > > I'm observing some network problems when using virtio and a tap if. > The trouble is a drop of network troughput from abot 90Mbit/s to about 90kbit/s, > after about 1.7 TB of transferred data. > > Setup > Host: > - Fedora 8, nearly all updates > - Intel(R) Xeon(R) CPU X3210 @ 2.13GHz > - 8GB RAM > - 2 Guests > > Guest: > - Fedora 9 all updates > - virtio nic using tap > - samba sharing a mountpoint using an iscsi target > > Steps to reproduce: > 1. Setup a guets using virtio and tap > 2. Mount an iscsi target and wokr on the fs or create some traffic on the nic. > 2.a I used: > # while true ; do sync ; \ > time dd if=/dev/zero of=test.bin bs=1M count=1024 ; sync ; > time md5sum test.bin ; done > 3. Wait a couple of days or about 1.7 TB of data on a 100Mbit/s. > > Expected results: > Everything runs fine, even after 2.5 TB of transferred data or more. > > Actual results: > Everything runs fine up to some point. > Then: Troughput drops a bit (from 11 MB/s to about 6MB/s). > At some point later the troughput drops to about 90kBit/s. > No messages on guest and host. No errors on ifconfig, no dmesg errors. > Ping latency increases over time. Logged here: > http://www.meinsandkasten.de/log-virtio.pdf > > > Did someone observ something similar or so? > > Greetings > fabian