Reintroduce rand()-based frequency selection in test-cdeque (useful on platforms where clock_gettime may trap into kernel mode)

Author: nhatminhle

libworkstream_df/benchmark-cdeque.sh

@@ -58,8 +58,12 @@ if [ -z "$randfile" ]; then
 	randfile=rand.$$
 	awk -v ni=$niter -v mu=$mu '
 	BEGIN {
-		for (i = 1; i <= ni; ++i)
-			print -log(rand()) * mu
+		for (i = 1; i <= ni; ++i) {
+			do
+				x = -log(rand()) * mu
+			while (mu <= 1.0 && x > 1.0)
+			print x
+		}
 	}
 	' >"$randfile"
 fi
@@ -71,7 +75,7 @@ for t in $tests; do
 	done
 	log=$t.$nthread.$b.$d.log
 	while read x; do
-		f=$(awk "BEGIN{print $x / ($nthread-1)}")
+		f=$(awk "BEGIN{print $mu <= 1.0 ? $x : $x / ($nthread-1)}")
 		echo $t $testargs -f $f >&2 \>\> $log
 		[ $dry ] || ./$t $testargs -f $f | tail -n 1 >>$log
 	done <"$randfile"

libworkstream_df/test-cdeque.c

@@ -46,6 +46,7 @@ static void worker (struct state *, unsigned long);
 static void straight_worker (struct state *, unsigned long);
 static void *thief_main (void *);
 static bool do_steal (struct state *, double *);
+static bool do_rand_steal (struct state *);
 
 static void *
 worker_main (void *data)
@@ -130,8 +131,16 @@ thief_main (void *data)
   lasttime = get_thread_cpu_time ();
   while (state->num_attempt < num_steal_per_thread)
     {
-      if (!do_steal (state, &lasttime))
-	break;
+      if (steal_freq <= 1.0)
+	{
+	  if (!do_rand_steal (state))
+	    break;
+	}
+      else
+	{
+	  if (!do_steal (state, &lasttime))
+	    break;
+	}
     }
 
   END_TIME (&state->time);
@@ -167,6 +176,26 @@ do_steal (struct state *state, double *plasttime)
   return true;
 }
 
+static bool
+do_rand_steal (struct state *state)
+{
+  void *val;
+
+  if ((double) rand_r (&state->seed) / RAND_MAX >= steal_freq)
+    return !atomic_load_explicit (&end, memory_order_acquire);
+  val = cdeque_steal (worker_deque);
+  if (val == NULL)
+    ++state->num_failed_attempt;
+  if (atomic_load_explicit (&end, memory_order_acquire))
+    {
+      if (num_steal_per_thread == (unsigned long) -1)
+	return false;
+    }
+  else
+    ++state->num_attempt;
+  return true;
+}
+
 int
 main (int argc, char *argv[])
 {

libworkstream_df/time-util.h

@@ -1,6 +1,7 @@
 #ifndef TIME_UTIL_H
 #define TIME_UTIL_H
 
+#include <assert.h>
 #include <stdatomic.h>
 #include <time.h>
 
@@ -10,23 +11,23 @@ static inline int timespec_diff (struct timespec *,
 				 const struct timespec *,
 				 const struct timespec *);
 
-#define BEGIN_TIME(p)				\
-do						\
-  {						\
-    atomic_thread_fence (memory_order_seq_cst);	\
-    clock_gettime (TIME_UTIL_CLOCK, (p));	\
-    atomic_thread_fence (memory_order_seq_cst);	\
-  }						\
+#define BEGIN_TIME(p)							    \
+do									    \
+  {									    \
+    atomic_thread_fence (memory_order_seq_cst);				    \
+    assert (clock_gettime (TIME_UTIL_CLOCK, (p)) == 0);			    \
+    atomic_thread_fence (memory_order_seq_cst);				    \
+  }									    \
 while (0)
-#define END_TIME(p)						\
-do								\
-  {								\
-    struct timespec _end_time_tv;				\
-    atomic_thread_fence (memory_order_seq_cst);			\
-    clock_gettime (TIME_UTIL_CLOCK, &_end_time_tv);		\
-    assert (timespec_diff ((p), &_end_time_tv, (p)) == 0);	\
-    atomic_thread_fence (memory_order_seq_cst);			\
-  }								\
+#define END_TIME(p)							    \
+do									    \
+  {									    \
+    struct timespec _end_time_tv;					    \
+    atomic_thread_fence (memory_order_seq_cst);				    \
+    assert (clock_gettime (TIME_UTIL_CLOCK, &_end_time_tv) == 0);	    \
+    assert (timespec_diff ((p), &_end_time_tv, (p)) == 0);		    \
+    atomic_thread_fence (memory_order_seq_cst);				    \
+  }									    \
 while (0)
 
 static inline double
@@ -35,7 +36,7 @@ get_thread_cpu_time (void)
   struct timespec _tv;
   double _t;
 
-  clock_gettime (CLOCK_THREAD_CPUTIME_ID, &_tv);
+  assert (clock_gettime (CLOCK_THREAD_CPUTIME_ID, &_tv) == 0);
   _t = _tv.tv_sec;
   _t += _tv.tv_nsec * 1e-9;
   return _t;