linux-toradex.git/tools/virtio/ringtest/main.c, branch v4.9.116

ringtest: poll for new buffers once before updating event index

2016-10-30T22:21:43+00:00

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 
Signed-off-by: Michael S. Tsirkin

ringtest: commonize implementation of poll_avail/poll_used

2016-10-30T22:21:43+00:00

Provide new primitives used_empty/avail_empty and
build poll_avail/poll_used on top of it.

Signed-off-by: Paolo Bonzini 
Signed-off-by: Michael S. Tsirkin

ringtest: use link-time optimization

2016-10-30T22:21:42+00:00

By using -flto and -fwhole-program, all functions from the ring implementation
can be treated as static and possibly inlined.  Force this to happen through
the GCC flatten attribute.

Signed-off-by: Paolo Bonzini 
Signed-off-by: Michael S. Tsirkin

ringtest: pass buf != NULL

2016-05-22T16:44:14+00:00

just a stub pointer for now.

Signed-off-by: Michael S. Tsirkin

tools/virtio: add ringtest utilities

2016-01-26T08:18:30+00:00

This adds micro-benchmarks useful for tuning virtio ring layouts.
Three layouts are currently implemented:

- virtio 0.9 compatible one
- an experimental extension bypassing the ring index, polling ring
  itself instead
- an experimental extension bypassing avail and used ring completely

Typical use:

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

It doesn't depend on the kernel directly, but it's handy
to have as much virtio stuff as possible in one tree.

Signed-off-by: Michael S. Tsirkin