From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53022) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XMcoq-0005bK-UB for qemu-devel@nongnu.org; Wed, 27 Aug 2014 08:59:27 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XMcom-0003E9-Pe for qemu-devel@nongnu.org; Wed, 27 Aug 2014 08:59:20 -0400 Received: from mx1.redhat.com ([209.132.183.28]:19630) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XMcom-0003E5-Gy for qemu-devel@nongnu.org; Wed, 27 Aug 2014 08:59:16 -0400 Date: Wed, 27 Aug 2014 14:59:39 +0200 From: "Michael S. Tsirkin" Message-ID: <20140827125939.GA17757@redhat.com> References: <1408424189-10510-1-git-send-email-jasowang@redhat.com> <53F46909.2040101@huawei.com> <53F575AF.2010100@redhat.com> <53F59174.7010104@huawei.com> <53F59771.2050602@redhat.com> <53F5A2FD.2060405@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <53F5A2FD.2060405@huawei.com> Subject: Re: [Qemu-devel] [PATCH V3] vhost_net: start/stop guest notifiers properly List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Zhangjie (HZ)" Cc: Jason Wang , qemu-devel@nongnu.org, William Dauchy On Thu, Aug 21, 2014 at 03:42:53PM +0800, Zhangjie (HZ) wrote: > On 2014/8/21 14:53, Jason Wang wrote: > > On 08/21/2014 02:28 PM, Zhangjie (HZ) wrote: > >> > >> After migration, vhost is not disabled, virtual nic became unreachable because vhost is not awakened. > >> By the logical of EVENT_IDX, virtio-net will not kick vhost again if the used idx is not updated. > >> So, if one interrupts is lost during migration, virtio_net will not kick vhost again. > >> Then, no skb from virtio-net can be sent to tap. > > > > Yes and I mean to test vhost=off to see if it was the issue of vhost. > That sounds reasonable, but the test case is to test vhost. > >> > >> Jason's patch reduced the probability of occurrence, from about 1/20 to 1/80. It is really effective. I think the patch should be acked. > >> May be we can try to solve the problem from another perspective. Do you have some methods to sense the migration? > >> We can make up a signal from virtio-net after the migration. > > > > You can make a patch like this to debug. If problem disappears, it means > > interrupt was really lost anyway. > >> > >>> Anyway, I will try to reproduce it by myself. > >>> > >> The test environment is really terrible, I build a environment myself, but it problem did not occur. > >> The environment I use now is from a colleague Responsible for test work. > >> Two hosts, every host has about 20 vms, they send packages(ipv4 and ipv6) between each other. > >> The VM to be migrated also sens packages itself, and there is a ping(-i 0.001) from another host to it. > >> The physical nic is 1GE, connected through a internal nework. > > > > Just want to confirm. For the problem did not occur, you mean with my > > patch on top? > > . > > > I mean, with your patch, I have to test 80 times before it occurs, the probability is reduced. Could you please try to apply the patch [PATCH V4] net: Forbid dealing with packets when VM is not running on top and see if this helps? Thanks! > -- > Best Wishes! > Zhang Jie