On Thu, Feb 20, 2014 at 11:21:10AM +1100, Chris Maltby wrote: > I'm not sure that this is the right place to raise this issue, so > apologies in advance. > > I have an RHEL6 system with two qemu/kvm guests, one running RHEL5 > (x64) and one running Windows 7 (x64). These variously provide local > and remote access net services in a small office environment. I have > configured networking using a bridge config and with guest virtio > drivers. There is no shortage of CPU or RAM on the host system or > in the guests. > > The problem is that bursts of traffic (eg rsync) between host and > guest or guest/guest result in the associated vhost process entering > a CPU loop which can last for up to 30 minutes. During this period > the net interface is offline. It recovers spontaneously after some > time and for no obvious reason. Using ifconfig down/up sequences > has no impact. Nothing is logged by the kernel or qemu-kvm. All > other network interfaces (physical and virtual) continue to function > normally. > > I can reproduce the problem in any virtual setup that uses vhost > networking. I have looked extensively in the Redhat forums etc and > haven't seen anyone else reporting a similar problem, nor have I > found any mention of anything like this in the kvm forums. Obviously, > these are not the current versions of the kernel or qemu-kvm, but > it may be that the problem still exists. > > The installed versions are: > > qemu-kvm-0.12.1.2-2.415.el6_5.3.x86_64 > qemu-img-0.12.1.2-2.415.el6_5.3.x86_64 > libvirt-0.10.2-29.el6_5.3.x86_64 > kernel-2.6.32-431.3.1.el6.x86_64 > > I can work around the problem by configuring qemu to perform the > network IO in process and not in a vhost thread, so it's clearly > a vhost issue. > > I have a very similar system at another site running an older version > of the kernel and qemu-kvm which does not exhibit the problem: > > qemu-kvm-0.12.1.2-2.295.el6_3.10.x86_64 > qemu-img-0.12.1.2-2.295.el6_3.10.x86_64 > libvirt-0.9.10-21.el6_3.8.x86_64 > kernel-2.6.32-279.19.1.el6.x86_64 Does the issue reproduce with the latest upstream release or git tree (linux.git + qemu.git)? If not (or if you cannot test upstream), please report this issue to Red Hat. The upstream mailing lists focus on linux.git/qemu.git. Stefan -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
