Mutex speedups cont'd

1 files changed, 205 insertions, 0 deletions

diff --git a/tests/rwlock8.c b/tests/rwlock8.c
new file mode 100644
index 0000000..c83a775
--- /dev/null
+++ b/tests/rwlock8.c
@@ -0,0 +1,205 @@
+/*
+ * rwlock8.c
+ *
+ * Hammer on a bunch of rwlocks to test robustness and fairness.
+ * Printed stats should be roughly even for each thread.
+ *
+ * Yield during each access to exercise lock contention code paths
+ * more than rwlock7.c does (particularly on uni-processor systems).
+ */
+
+#include "test.h"
+#include <sys/timeb.h>
+
+#ifdef __GNUC__
+#include <stdlib.h>
+#endif
+
+#define THREADS         5
+#define DATASIZE        7
+#define ITERATIONS      100000
+
+/*
+ * Keep statistics for each thread.
+ */
+typedef struct thread_tag {
+  int         thread_num;
+  pthread_t   thread_id;
+  int         updates;
+  int         reads;
+  int         changed;
+  int         seed;
+} thread_t;
+
+/*
+ * Read-write lock and shared data
+ */
+typedef struct data_tag {
+  pthread_rwlock_t    lock;
+  int                 data;
+  int                 updates;
+} data_t;
+
+static thread_t threads[THREADS];
+static data_t data[DATASIZE];
+
+/*
+ * Thread start routine that uses read-write locks
+ */
+void *thread_routine (void *arg)
+{
+  thread_t *self = (thread_t*)arg;
+  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++)
+    {
+      if (iteration % (ITERATIONS / 10) == 0)
+        {
+          putchar('.');
+          fflush(stdout);
+        }
+      /*
+       * Each "self->interval" iterations, perform an
+       * update operation (write lock instead of read
+       * lock).
+       */
+      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;
+	  sched_yield();
+          assert(pthread_rwlock_unlock (&data[element].lock) == 0);
+        } else {
+          /*
+           * Look at the current data element to see whether
+           * the current thread last updated it. Count the
+           * times, to report later.
+           */
+          assert(pthread_rwlock_rdlock (&data[element].lock) == 0);
+
+          self->reads++;
+
+          if (data[element].data != self->thread_num)
+            {
+              self->changed++;
+	      interval = 1 + self->changed % 71;
+            }
+
+	  sched_yield();
+
+          assert(pthread_rwlock_unlock (&data[element].lock) == 0);
+        }
+
+      element = (element + 1) % DATASIZE;
+
+    }
+
+  return NULL;
+}
+
+int
+main (int argc, char *argv[])
+{
+  int count;
+  int data_count;
+  int thread_updates = 0;
+  int data_updates = 0;
+  int seed = 1;
+
+  struct _timeb currSysTime1;
+  struct _timeb currSysTime2;
+
+  /*
+   * Initialize the shared data.
+   */
+  for (data_count = 0; data_count < DATASIZE; data_count++)
+    {
+      data[data_count].data = 0;
+      data[data_count].updates = 0;
+
+      assert(pthread_rwlock_init (&data[data_count].lock, NULL) == 0);
+    }
+
+  _ftime(&currSysTime1);
+
+  /*
+   * Create THREADS threads to access shared data.
+   */
+  for (count = 0; count < THREADS; count++)
+    {
+      threads[count].thread_num = count;
+      threads[count].updates = 0;
+      threads[count].reads = 0;
+      threads[count].seed = 1 + rand_r (&seed) % 71;
+
+      assert(pthread_create (&threads[count].thread_id,
+                             NULL, thread_routine, (void*)&threads[count]) == 0);
+    }
+
+  /*
+   * Wait for all threads to complete, and collect
+   * statistics.
+   */
+  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 ("%02d: seed %d, updates %d, reads %d\n",
+              count, threads[count].seed,
+              threads[count].updates, threads[count].reads);
+    }
+
+  putchar('\n');
+  fflush(stdout);
+
+  /*
+   * Collect statistics for the data.
+   */
+  for (data_count = 0; data_count < DATASIZE; data_count++)
+    {
+      data_updates += data[data_count].updates;
+      printf ("data %02d: value %d, %d updates\n",
+              data_count, data[data_count].data, data[data_count].updates);
+      assert(pthread_rwlock_destroy (&data[data_count].lock) == 0);
+    }
+
+  printf ("%d thread updates, %d data updates\n",
+          thread_updates, data_updates);
+
+  _ftime(&currSysTime2);
+
+  printf( "\nstart: %ld/%d, stop: %ld/%d, duration:%ld\n",
+          currSysTime1.time,currSysTime1.millitm,
+          currSysTime2.time,currSysTime2.millitm,
+          (currSysTime2.time*1000+currSysTime2.millitm) -
+          (currSysTime1.time*1000+currSysTime1.millitm));
+
+  return 0;
+}