On Wed, 2008-08-13 at 16:01 +0100, Daniel P. Berrange wrote:
On Wed, Aug 13, 2008 at 03:53:27PM +0100, Mark McLoughlin wrote:
By enabling this flag on the tap fds we create, we greatly increase the achievable throughput with virtio_net.
However, we need to be careful to only set the flag when a) KVM has support for this ABI and b) the value of the flag is queryable using the TUNGETIFF ioctl.
This suggests to me that QEMU should be a the one enabling this flag, not libvirt.
It has to be done before adding it to the bridge and can't be changed afterwards. (Which perhaps suggests the kernel API is a little dumb, but ...)
Its going to need todo this anyway for the scenario where QEMU allocates the TAP fd, so it might as well enable it for pre-allocated TAP fds passed in from external apps.
Yeah, it already does it for the fds it allocates. Cheers, Mark.