tools/virtio: add ringtest utilities

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 <mst@redhat.com>

1 files changed, 24 insertions, 0 deletions

diff --git a/tools/virtio/ringtest/run-on-all.sh b/tools/virtio/ringtest/run-on-all.sh
new file mode 100755
index 000000000000..52b0f71ffa8d
--- /dev/null
+++ b/tools/virtio/ringtest/run-on-all.sh
@@ -0,0 +1,24 @@
+#!/bin/sh
+
+#use last CPU for host. Why not the first?
+#many devices tend to use cpu0 by default so
+#it tends to be busier
+HOST_AFFINITY=$(cd /dev/cpu; ls|grep -v '[a-z]'|sort -n|tail -1)
+
+#run command on all cpus
+for cpu in $(cd /dev/cpu; ls|grep -v '[a-z]'|sort -n);
+do
+	#Don't run guest and host on same CPU
+	#It actually works ok if using signalling
+	if
+		(echo "$@" | grep -e "--sleep" > /dev/null) || \
+			test $HOST_AFFINITY '!=' $cpu
+	then
+		echo "GUEST AFFINITY $cpu"
+		"$@" --host-affinity $HOST_AFFINITY --guest-affinity $cpu
+	fi
+done
+echo "NO GUEST AFFINITY"
+"$@" --host-affinity $HOST_AFFINITY
+echo "NO AFFINITY"
+"$@"