schedbench

43a57743 · Silas Boyd-Wickizer · 25fa822b · 43a57743 · 43a57743
--- a/bin/Makefrag
+++ b/bin/Makefrag
@@ -37,7 +37,7 @@ UPROGS= \
 	wqtest \
 	rm \
 	avar \
-        futexbench
+	schedbench

 ifeq ($(HAVE_LWIP),y)
 UPROGS += \

--- a/bin/futexbench.cc
+++ b/bin/futexbench.cc
@@ -4,47 +4,68 @@
 #include "pthread.h"
 #include "futex.h"
 #include "errno.h"
+#include "atomic.hh"

+static volatile std::atomic<u64> waiting;
 static volatile u64 ftx;
 static int iters;
+static int nworkers;

-static void*
-worker(void *arg)
+static
+void* worker(void* x)
 {
  long r;

  for (int i = 0; i < iters; i++) {
-    r = futex((u64*)&ftx, FUTEX_WAIT, 0, 0);
+    ++waiting;
+    r = futex((u64*)&ftx, FUTEX_WAIT, (u64)i, 0);
    if (r < 0 && r != -EWOULDBLOCK)
      die("FUTEX_WAIT: %d", r);
-    ftx = 0;
-    r = futex((u64*)&ftx, FUTEX_WAKE, 1, 0);    
  }
  return nullptr;
 }

+static
+void master(void)
+{
+  long r;
+
+  for (int i = 0; i < iters; i++) {
+    while (waiting.load() < nworkers)
+      nop_pause();
+    waiting.store(0);
+
+    ftx = i+1;
+    r = futex((u64*)&ftx, FUTEX_WAKE, nworkers, 0);  
+    assert(r == 0);
+  }
+}
+
 int
 main(int ac, char** av)
 {
-  pthread_t th;
  long r;

-  if (ac < 2)
-    die("usage: %s iters", av[0]);
-
+  if (ac < 3)
+    die("usage: %s iters nworkers", av[0]);
  iters = atoi(av[1]);
+  nworkers = atoi(av[2]);
+  waiting.store(0);

-  pthread_create(&th, 0, &worker, 0);
-  for (int i = 0; i < iters; i++) {
-    ftx = 1;
-    r = futex((u64*)&ftx, FUTEX_WAKE, 1, 0);
-    assert(r == 0);
-    r = futex((u64*)&ftx, FUTEX_WAIT, 1, 0);    
-    if (r < 0 && r != -EWOULDBLOCK)
-      die("FUTEX_WAIT: %d", r);
+  for (int i = 0; i < nworkers; i++) {
+    pthread_t th;
+
+    r = pthread_create(&th, nullptr, worker, nullptr);
+    if (r < 0)
+      die("pthread_create");
  }
+  nsleep(1000*1000);

-  wait();
-  printf("done\n");
-  return 0;
+  u64 t0 = rdtsc();
+  master();
+  u64 t1 = rdtsc();
+  printf("%lu\n", (t1-t0)/iters);
+  
+  for (int i = 0; i < nworkers; i++)
+    wait();
 }