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>
diff --git a/tools/virtio/ringtest/run-on-all.sh b/tools/virtio/ringtest/run-on-all.sh
new file mode 100755
index 0000000..52b0f71
--- /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 $HOST_AFFINITY
+echo "NO AFFINITY"
+"$@"