benchtests: Add pthread_once common-case test.

We have a single thread that runs a no-op initialization once and then
repeatedly runs checks of the initialization (i.e., an acquire load and
conditional jump) in a tight loop.  This gives us, on average, the
best-case latency of pthread_once (the initialization is the
exactly-once slow path, and we're not looking at initialization-related
synchronization overheads in this case).

1 files changed, 9 insertions, 0 deletions

diff --git a/benchtests/pthread_once-inputs b/benchtests/pthread_once-inputs
new file mode 100644
index 0000000000..22c57096f7
--- /dev/null
+++ b/benchtests/pthread_once-inputs
@@ -0,0 +1,9 @@
+# This tests the common-case scenario for pthread_once.
+# We have a single thread that runs a no-op initialization once and then
+# repeatedly runs checks of the initialization (i.e., an acquire load and
+# conditional jump) in a tight loop.
+# scripts/bench.py doesn't handle function pointers, so we just use void *:
+## args: pthread_once_t *:void *
+## includes: pthread.h
+## include-sources: pthread_once-source.c
+&once, once_handler