--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/third_party/libuv/test/benchmark-async-pummel.c	Wed Jan 14 19:39:52 2026 -0800
@@ -0,0 +1,120 @@
+/* Copyright Joyent, Inc. and other Node contributors. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include "task.h"
+#include "uv.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#define NUM_PINGS               (1000 * 1000)
+#define ACCESS_ONCE(type, var)  (*(volatile type*) &(var))
+
+static unsigned int callbacks;
+static volatile int done;
+
+static const char running[] = "running";
+static const char stop[]    = "stop";
+static const char stopped[] = "stopped";
+
+
+static void async_cb(uv_async_t* handle) {
+  if (++callbacks == NUM_PINGS) {
+    /* Tell the pummel thread to stop. */
+    ACCESS_ONCE(const char*, handle->data) = stop;
+
+    /* Wait for the pummel thread to acknowledge that it has stoppped. */
+    while (ACCESS_ONCE(const char*, handle->data) != stopped)
+      uv_sleep(0);
+
+    uv_close((uv_handle_t*) handle, NULL);
+  }
+}
+
+
+static void pummel(void* arg) {
+  uv_async_t* handle = (uv_async_t*) arg;
+
+  while (ACCESS_ONCE(const char*, handle->data) == running)
+    uv_async_send(handle);
+
+  /* Acknowledge that we've seen handle->data change. */
+  ACCESS_ONCE(const char*, handle->data) = stopped;
+}
+
+
+static int test_async_pummel(int nthreads) {
+  char fmtbuf[2][32];
+  uv_thread_t* tids;
+  uv_async_t handle;
+  uint64_t time;
+  int i;
+
+  tids = calloc(nthreads, sizeof(tids[0]));
+  ASSERT_NOT_NULL(tids);
+
+  ASSERT_OK(uv_async_init(uv_default_loop(), &handle, async_cb));
+  ACCESS_ONCE(const char*, handle.data) = running;
+
+  for (i = 0; i < nthreads; i++)
+    ASSERT_OK(uv_thread_create(tids + i, pummel, &handle));
+
+  time = uv_hrtime();
+
+  ASSERT_OK(uv_run(uv_default_loop(), UV_RUN_DEFAULT));
+
+  time = uv_hrtime() - time;
+  done = 1;
+
+  for (i = 0; i < nthreads; i++)
+    ASSERT_OK(uv_thread_join(tids + i));
+
+  printf("async_pummel_%d: %s callbacks in %.2f seconds (%s/sec)\n",
+         nthreads,
+         fmt(&fmtbuf[0], callbacks),
+         time / 1e9,
+         fmt(&fmtbuf[1], callbacks / (time / 1e9)));
+
+  free(tids);
+
+  MAKE_VALGRIND_HAPPY(uv_default_loop());
+  return 0;
+}
+
+
+BENCHMARK_IMPL(async_pummel_1) {
+  return test_async_pummel(1);
+}
+
+
+BENCHMARK_IMPL(async_pummel_2) {
+  return test_async_pummel(2);
+}
+
+
+BENCHMARK_IMPL(async_pummel_4) {
+  return test_async_pummel(4);
+}
+
+
+BENCHMARK_IMPL(async_pummel_8) {
+  return test_async_pummel(8);
+}