Re: [Qemu-devel] [PATCH] vhost: force vhost off for non-MSI guests

[rukhsana ansari]

Hi,

On Thu, Jan 20, 2011 at 9:05 PM, Michael S. Tsirkin <address@hidden> wrote:

When MSI is off, each interrupt needs to be bounced through the io
thread when it's set/cleared, so vhost-net causes more context switches and
higher CPU utilization than userspace virtio which handles networking in
the same thread.

We'll need to fix this by adding level irq support in kvm irqfd,
for now disable vhost-net in these configurations.

This maybe a novice question - Would appreciate it if you can you provide a pointer to documentation or relevant code that explains what is the limitation in supporting level irq support in kvm irqfd. 


Thanks
-Rukhsana