Merge branch 'thread' into fs

Conflicts:
	.gitignore
	Makefile
	conf/lab.mk
    kernel/param.h

1 files changed, 86 insertions, 0 deletions

diff --git a/notxv6/barrier.c b/notxv6/barrier.c
new file mode 100644
index 0000000..b7737a6
--- /dev/null
+++ b/notxv6/barrier.c
@@ -0,0 +1,86 @@
+#include <stdlib.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <assert.h>
+#include <pthread.h>
+
+static int nthread = 1;
+static int round = 0;
+
+struct barrier {
+  pthread_mutex_t barrier_mutex;
+  pthread_cond_t barrier_cond;
+  int nthread;      // Number of threads that have reached this round of the barrier
+  int round;     // Barrier round
+} bstate;
+
+static void
+barrier_init(void)
+{
+  assert(pthread_mutex_init(&bstate.barrier_mutex, NULL) == 0);
+  assert(pthread_cond_init(&bstate.barrier_cond, NULL) == 0);
+  bstate.nthread = 0;
+}
+
+static void 
+barrier()
+{
+  // Block until all threads have called barrier() and
+  // then increment bstate.round.
+  pthread_mutex_lock(&bstate.barrier_mutex);
+  bstate.nthread++;
+  if(bstate.nthread != nthread) {
+    pthread_cond_wait(&bstate.barrier_cond, &bstate.barrier_mutex);
+  } else {
+    pthread_cond_broadcast(&bstate.barrier_cond);
+    // All threads have reached barrier.
+    // reset and increase round
+    bstate.nthread = 0;
+    bstate.round++;
+  }
+  pthread_mutex_unlock(&bstate.barrier_mutex);
+}
+
+static void *
+thread(void *xa)
+{
+  long n = (long) xa;
+  long delay;
+  int i;
+
+  for (i = 0; i < 20000; i++) {
+    int t = bstate.round;
+    assert (i == t);
+    barrier();
+    usleep(random() % 100);
+  }
+
+  return 0;
+}
+
+int
+main(int argc, char *argv[])
+{
+  pthread_t *tha;
+  void *value;
+  long i;
+  double t1, t0;
+
+  if (argc < 2) {
+    fprintf(stderr, "%s: %s nthread\n", argv[0], argv[0]);
+    exit(-1);
+  }
+  nthread = atoi(argv[1]);
+  tha = malloc(sizeof(pthread_t) * nthread);
+  srandom(0);
+
+  barrier_init();
+
+  for(i = 0; i < nthread; i++) {
+    assert(pthread_create(&tha[i], NULL, thread, (void *) i) == 0);
+  }
+  for(i = 0; i < nthread; i++) {
+    assert(pthread_join(tha[i], &value) == 0);
+  }
+  printf("OK; passed\n");
+}