time, in terms of hw cycles

f844189d · Nickolai Zeldovich · 289a4b72 · f844189d · f844189d · f844189d
--- a/Makefile
+++ b/Makefile
@@ -88,6 +88,8 @@ UPROGS= \
 	_sh \
 	_thrtest \
 	_halt \
+	_time \
+	_sleep \
 	_usertests
 UPROGS := $(addprefix $(O)/, $(UPROGS))


--- a/sleep.c
+++ b/sleep.c
 #include "types.h"
 #include "stat.h"
 #include "user.h"
+#include "fcntl.h"
+#include "amd64.h"

 int
-main(void)
+main(int ac, char *av[])
 {
-  int i;
-
-  for (i = 0; i < 10000000; i++) {
-    sleep(1);
+  if (ac != 2) {
+    printf(1, "Usage: %s ticks\n", av[0]);
+    exit();
  }
+
+  sleep(atoi(av[1]));
+  exit();
 }
--- a/time.c
+++ b/time.c
+#include "types.h"
+#include "stat.h"
+#include "user.h"
+#include "fcntl.h"
+#include "amd64.h"
+
+int
+main(int ac, char *av[])
+{
+  u64 t0 = rdtsc();
+
+  int pid = fork(0);
+  if (pid < 0) {
+    printf(1, "time: fork failed\n");
+    exit();
+  }
+
+  if (pid == 0) {
+    exec(av[1], av+1);
+    printf(1, "time: exec failed\n");
+    exit();
+  }
+
+  wait();
+  u64 t1 = rdtsc();
+  printf(1, "%lu cycles\n", t1-t0);
+  exit();
+}