Mutex speedups cont'd

1 files changed, 35 insertions, 21 deletions

diff --git a/tests/rwlock7.c b/tests/rwlock7.c
index 8706d4a..91466e4 100644
--- a/tests/rwlock7.c
+++ b/tests/rwlock7.c
@@ -13,7 +13,7 @@
 #endif
 
 #define THREADS         5
-#define DATASIZE        15
+#define DATASIZE        7
 #define ITERATIONS      1000000
 
 /*
@@ -24,7 +24,8 @@ typedef struct thread_tag {
   pthread_t   thread_id;
   int         updates;
   int         reads;
-  int         interval;
+  int         changed;
+  int         seed;
 } thread_t;
 
 /*
@@ -45,9 +46,12 @@ static data_t data[DATASIZE];
 void *thread_routine (void *arg)
 {
   thread_t *self = (thread_t*)arg;
-  int repeats = 0;
   int iteration;
   int element = 0;
+  int seed = self->seed;
+  int interval = 1 + rand_r (&seed) % 71;
+
+  self->changed = 0;
 
   for (iteration = 0; iteration < ITERATIONS; iteration++)
     {
@@ -61,12 +65,13 @@ void *thread_routine (void *arg)
        * update operation (write lock instead of read
        * lock).
        */
-      if ((iteration % self->interval) == 0)
+      if ((iteration % interval) == 0)
         {
           assert(pthread_rwlock_wrlock (&data[element].lock) == 0);
           data[element].data = self->thread_num;
           data[element].updates++;
           self->updates++;
+	  interval = 1 + rand_r (&seed) % 71;
           assert(pthread_rwlock_unlock (&data[element].lock) == 0);
         } else {
           /*
@@ -78,27 +83,17 @@ void *thread_routine (void *arg)
 
           self->reads++;
 
-          if (data[element].data == self->thread_num)
+          if (data[element].data != self->thread_num)
             {
-              repeats++;
+              self->changed++;
+	      interval = 1 + self->changed % 71;
             }
 
           assert(pthread_rwlock_unlock (&data[element].lock) == 0);
         }
 
-      element++;
-
-      if (element >= DATASIZE)
-        {
-          element = 0;
-        }
-    }
+      element = (element + 1) % DATASIZE;
 
-  if (repeats > 0)
-    {
-      printf ("\nThread %d found unchanged elements %d times",
-              self->thread_num, repeats);
-      fflush(stdout);
     }
 
   return NULL;
@@ -137,7 +132,7 @@ main (int argc, char *argv[])
       threads[count].thread_num = count;
       threads[count].updates = 0;
       threads[count].reads = 0;
-      threads[count].interval = rand_r (&seed) % 71;
+      threads[count].seed = 1 + rand_r (&seed) % 71;
 
       assert(pthread_create (&threads[count].thread_id,
                              NULL, thread_routine, (void*)&threads[count]) == 0);
@@ -150,9 +145,28 @@ main (int argc, char *argv[])
   for (count = 0; count < THREADS; count++)
     {
       assert(pthread_join (threads[count].thread_id, NULL) == 0);
+    }
+
+  putchar('\n');
+  fflush(stdout);
+
+  for (count = 0; count < THREADS; count++)
+    {
+      if (threads[count].changed > 0)
+        {
+          printf ("Thread %d found changed elements %d times\n",
+                  count, threads[count].changed);
+        }
+    }
+
+  putchar('\n');
+  fflush(stdout);
+
+  for (count = 0; count < THREADS; count++)
+    {
       thread_updates += threads[count].updates;
-      printf ("\n%02d: interval %d, updates %d, reads %d\n",
-              count, threads[count].interval,
+      printf ("%02d: seed %d, updates %d, reads %d\n",
+              count, threads[count].seed,
               threads[count].updates, threads[count].reads);
     }