exechack bm

a0d400a8 · Silas Boyd-Wickizer · 14a1d1df · a0d400a8 · a0d400a8
--- a/bin/Makefrag
+++ b/bin/Makefrag
@@ -6,6 +6,7 @@ UPROGS= \
 	cat \
        du \
 	echo \
+        exechack \
 	init \
 	forkexectree \
 	forkexecbench \

--- a/bin/exechack.cc
+++ b/bin/exechack.cc
+#include "types.h"
+#include "stat.h"
+#include "user.h"
+#include "mtrace.h"
+#include "amd64.h"
+
+#define NITERS 100
+
+#define PROCMAX NCPU
+#define PROCMIN (NCPU-4)
+
+static void
+worker0(void)
+{
+  const char* av[] = { "exechack", "w", 0 };
+  exec(av[0], av);
+  die("worker exec");
+}
+
+static void
+worker1(void)
+{
+  exit();
+}
+
+static void
+master(void)
+{
+  u64 pcount = 0;
+  u64 i = 0;
+
+  u64 t0 = rdtsc();
+  while (i < NITERS) {
+    while (pcount < PROCMAX) {
+      int pid;
+      pid = fork(0);
+      if (pid < 0)
+        die("master fork");
+      if (pid == 0)
+        worker0();
+      pcount++;
+    }
+    
+    while (pcount > PROCMIN) {
+      if (wait() < 0)
+        die("master wait");
+      pcount--;
+      i++;
+    }
+  }
+
+  while (pcount) {
+    wait();
+    pcount--;
+  }
+  u64 t1 = rdtsc();
+
+  printf("%lu\n", (t1-t0)/i);
+}
+
+int
+main(int ac, char **av)
+{
+  if (ac > 1 && av[1][0] == 'w')
+    worker1();
+  master();
+}