kernel_optimize_test/tools/virtio/ringtest
Paolo Bonzini 948a8ac296 ringtest: poll for new buffers once before updating event index
Updating the event index has a memory barrier and causes more work
on the other side to actually signal the event.  It is unnecessary
if a new buffer has already appeared on the ring, so poll once before
doing the update.

The effect of this on the 0.9 ring implementation is pretty much
invisible, but on the new-style ring it provides a consistent 3%
performance improvement.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
2016-10-31 00:21:43 +02:00
..
main.c ringtest: poll for new buffers once before updating event index 2016-10-31 00:21:43 +02:00
main.h ringtest: commonize implementation of poll_avail/poll_used 2016-10-31 00:21:43 +02:00
Makefile
noring.c ringtest: commonize implementation of poll_avail/poll_used 2016-10-31 00:21:43 +02:00
ptr_ring.c ringtest: commonize implementation of poll_avail/poll_used 2016-10-31 00:21:43 +02:00
README
ring.c ringtest: commonize implementation of poll_avail/poll_used 2016-10-31 00:21:43 +02:00
run-on-all.sh
virtio_ring_0_9.c ringtest: commonize implementation of poll_avail/poll_used 2016-10-31 00:21:43 +02:00
virtio_ring_inorder.c
virtio_ring_poll.c

Partial implementation of various ring layouts, useful to tune virtio design.
Uses shared memory heavily.

Typical use:

# sh run-on-all.sh perf stat -r 10 --log-fd 1 -- ./ring