| Message ID | 20170111083815.19941-1-pbonzini@redhat.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c index 023a020..0cd42ae 100644 --- a/hw/virtio/virtio-pci.c +++ b/hw/virtio/virtio-pci.c @@ -2278,7 +2278,7 @@ static const TypeInfo virtio_serial_pci_info = { static Property virtio_net_properties[] = { DEFINE_PROP_BIT("ioeventfd", VirtIOPCIProxy, flags, - VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT, false), + VIRTIO_PCI_FLAG_USE_IOEVENTFD_BIT, true), DEFINE_PROP_UINT32("vectors", VirtIOPCIProxy, nvectors, 3), DEFINE_PROP_END_OF_LIST(), };
virtio-net-pci does not enable ioeventfd for historical reasons (and nobody ever checked whether it should be revisited). Note that other backends do enable ioeventfd for virtio-net. However, it has a major effect on performance. On Windows, throughput is _multiplied_ by 2 or 3 on TCP_STREAM (on small packets it is "only" a 30% improvement) and a little less so on TCP_MAERTS albeit still very much statistically significant. Latency also has a single digit improvement. This is not visible when using vhost, which forces ioeventfd=on, but it is substantial without vhost. In addition, also on Windows and with the RHEL 7.3 kernel, APICv seems to slow down virtio-net performance a bit, but the penalty with this patch goes from -25% to -7%. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> --- hw/virtio/virtio-pci.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)