From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:45100) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UcrfI-0005OB-UJ for qemu-devel@nongnu.org; Thu, 16 May 2013 02:27:55 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UcrfC-00006G-Lg for qemu-devel@nongnu.org; Thu, 16 May 2013 02:27:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:65474) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UcrfC-000062-EN for qemu-devel@nongnu.org; Thu, 16 May 2013 02:27:42 -0400 Date: Thu, 16 May 2013 09:27:43 +0300 From: "Michael S. Tsirkin" Message-ID: <20130516062743.GB26548@redhat.com> References: <20121123110146.GC7051@redhat.com> <50FE5607.9020405@dlhnet.de> <20130123100312.GA8108@redhat.com> <5119E9DC.3000505@dlhnet.de> <1368541284.15129.317.camel@eboracum.office.bytemark.co.uk> <519249F6.3000900@dlhnet.de> <1368542949.15129.354.camel@eboracum.office.bytemark.co.uk> <1368615603.15129.1471.camel@eboracum.office.bytemark.co.uk> <20130516062405.GA26548@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130516062405.GA26548@redhat.com> Subject: Re: [Qemu-devel] tap devices not receiving packets from a bridge List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Nicholas Thomas Cc: Stefan Hajnoczi , Peter Lieven , qemu-devel@nongnu.org, netdev@vger.kernel.org On Thu, May 16, 2013 at 09:24:05AM +0300, Michael S. Tsirkin wrote: > On Wed, May 15, 2013 at 12:00:03PM +0100, Nicholas Thomas wrote: > > Hi again, > > > > On Tue, 2013-05-14 at 15:49 +0100, Nicholas Thomas wrote: > > > /sys/devices/virtual/net/t100/tun_flags is 0x5002 - so it looks like > > > IFF_ONE_QUEUE was indeed unset by qemu (which is lacking the patch). It > > > surprises me, but that's probably my fault, rather than qemu's. > > > > > > I've rebuilt 1.4.1 with the IFF_ONE_QUEUE patch and tun_flags is now > > 0x7002; unfortunately, I'm still seeing this bug, twice in five trials. > > Symptoms in `ifconfig t100` now differ; overruns stays at 0, and > > "dropped" increases monotonically as I send packets. Those packets do > > appear if I tcpdump t100 on the host, but not if I tcpdump t100 on the > > guest. > > > > I've turned off gro in the guest, which makes no difference, and tried > > changing the queue sizes (post-hoc) in both guest and host, in the hope > > of causing them to be emptied out, clearing the condition; again to no > > effect. > > > > The VMs in question are bridged to a large (and busy) VLAN with no > > ingress filtering to speak of; I guess what's happening is that the > > transmit queue is filled up by that traffic while the guest is in ipxe, > > and it never gets out of that state when it happens... so maybe there is > > still an underlying problem? > > > > /Nick > > > Is this with or without vhost-net in host? never mind, I see it's without. Try to enable vhost-net (you'll have to switch to -netdev syntax for that to work) and see if this help. If it does it's likely a qemu bug if not probably a guest bug. > -- > MST