avoid race condition in mapbench that triggers some bug in mscan

80cdc1be · Nickolai Zeldovich · 207c8bac · 80cdc1be
--- a/bin/mapbench.cc
+++ b/bin/mapbench.cc
@@ -11,6 +11,7 @@ enum { verbose = 0 };
 enum { npg = 1 };

 static pthread_barrier_t bar;
+static pthread_barrier_t bar2;
 #define NITER 10  // 1000000

 void*
@@ -25,6 +26,8 @@ thr(void *arg)
  if (tid == 0)
    mtenable_type(mtrace_record_ascope, "xv6-asharing");

+  pthread_barrier_wait(&bar2);
+
  for (int i = 0; i < NITER; i++) {
    if (verbose && ((i % 100) == 0))
      fprintf(1, "%d: %d ops\n", tid, i);
@@ -60,6 +63,7 @@ main(int ac, char **av)

  // fprintf(1, "mapbench[%d]: start esp %x, nthread=%d\n", getpid(), rrsp(), nthread);
  pthread_barrier_init(&bar, 0, nthread);
+  pthread_barrier_init(&bar2, 0, nthread);

  for(u64 i = 0; i < nthread; i++) {
    pthread_t tid;