From mboxrd@z Thu Jan 1 00:00:00 1970 From: Emmanuel Lacour Subject: Re: virtio_net hang Date: Thu, 13 Nov 2008 16:24:52 +0100 Message-ID: <20081113152452.GI14254@easter-eggs.com> References: <20081113122709.GB14254@easter-eggs.com> <1226589153.19068.7.camel@blaa> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii To: kvm@vger.kernel.org Return-path: Received: from roxane.home-dn.net ([88.191.11.98]:36439 "EHLO roxane.home-dn.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750986AbYKMPY5 (ORCPT ); Thu, 13 Nov 2008 10:24:57 -0500 Received: from localhost (localhost.localdomain [127.0.0.1]) by roxane.home-dn.net (Postfix) with ESMTP id 862BD2C056 for ; Thu, 13 Nov 2008 16:24:56 +0100 (CET) Received: from datura.easter-eggs.fr (unknown [IPv6:2001:7a8:115a:1:214:22ff:feb4:f4ea]) by roxane.home-dn.net (Postfix) with ESMTP id 700D42C055 for ; Thu, 13 Nov 2008 16:24:55 +0100 (CET) Content-Disposition: inline In-Reply-To: <1226589153.19068.7.camel@blaa> Sender: kvm-owner@vger.kernel.org List-ID: On Thu, Nov 13, 2008 at 03:12:33PM +0000, Mark McLoughlin wrote: > The fact that re-loading the virtio_net driver fixes things up makes me > suspect you've found a bug in the virtio_net driver, rather than e.g. a > bug in the kvm-userspace side. > > To try and narrow down what's happening, when the interface has hung, > try: > > - tcpdump on both eth0 in the guest and the tap device on the host > (tap5 in your example) > > - look for anything unusual in the stats for both those interfaces, > e.g. /proc/net/dev, netstat -s etc. > > - strace the /usr/bin/kvm process > > What you're looking for e.g. is whether a guest->host ping is failing > because the request packet isn't getting to the host or because the > reply packet isn't getting to the guest, and where exactly the packet is > being blocked. > Nice hints, thanks, I will try to debug that deeper and come back with more informations :)