aha/drivers/virtio
Rusty Russell 44653eae14 virtio: don't always force a notification when ring is full
We force notification when the ring is full, even if the host has
indicated it doesn't want to know.  This seemed like a good idea at
the time: if we fill the transmit ring, we should tell the host
immediately.

Unfortunately this logic also applies to the receiving ring, which is
refilled constantly.  We should introduce real notification thesholds
to replace this logic.  Meanwhile, removing the logic altogether breaks
the heuristics which KVM uses, so we use a hack: only notify if there are
outgoing parts of the new buffer.

Here are the number of exits with lguest's crappy network implementation:
Before:
	network xmit 7859051 recv 236420
After:
	network xmit 7858610 recv 118136

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2008-07-25 12:06:04 +10:00
..
config.c Virtio interface 2007-10-23 15:49:54 +10:00
Kconfig virtio: balloon driver 2008-02-04 23:50:13 +11:00
Makefile virtio: balloon driver 2008-02-04 23:50:13 +11:00
virtio.c virtio: Complete feature negotation before updating status 2008-06-15 13:46:16 -07:00
virtio_balloon.c virtio: explicit advertisement of driver features 2008-05-02 21:50:50 +10:00
virtio_pci.c virtio: set device index in common code. 2008-05-30 15:09:42 +10:00
virtio_ring.c virtio: don't always force a notification when ring is full 2008-07-25 12:06:04 +10:00