Am 13.11.2012 um 17:33 schrieb Michael S. Tsirkin: > On Tue, Nov 13, 2012 at 06:22:56PM +0200, Michael S. Tsirkin wrote: >> On Tue, Nov 13, 2012 at 12:49:03PM +0100, Peter Lieven wrote: >>> >>> On 09.11.2012 19:03, Peter Lieven wrote: >>>> Remark: >>>> If i disable interrupts on CPU1-3 for virtio the performance is ok again. >>>> >>>> Now we need someone with deeper knowledge of the in-kernel irqchip and the >>>> virtio/vhost driver development to say if this is a regression in qemu-kvm >>>> or a problem with the old virtio drivers if they receive the interrupt on >>>> different CPUs. >>> anyone? >> >> Looks like the problem is not in the guest: I tried ubuntu guest >> on a rhel host, I got 8GB/s with vhost and 4GB/s without >> on a host to guest banchmark. >> > > Tried with upstream qemu on rhel kernel and that's even a bit faster. > So it's ubuntu kernel. vanilla 2.6.32 didn't have vhost at all > so maybe their vhost backport is broken insome way.
That might be. I think Dietmar was reporting that he had problems with Debian. They likely use the same back port. Is it correct that with kernel_irqchip the IRQs are delivered to all vCPUs? Without kernel_irqchip (in qemu-kvm 1.0.1 for instance) they where delivered only to vCPU 0. This scenario was working. Peter
