Remove my lame start sync and start recording before setup

Turns out mscan deals just fine with the benchmark setup

bin/dirbench.cc

@@ -22,10 +22,15 @@ static const bool pinit = true;
 enum { nfile = MTRACE ? 2 : 10 };
 enum { nlookup = MTRACE ? 2 : 100 };
 
+// XXX(austin) Totally lame.  Put this buffer in the BSS so we don't
+// have to COW fault the stack.
+static char pn[32]
+__attribute__((aligned(4096)));
+
 void
 bench(u32 tid, int nloop, const char* path)
 {
-  char pn[32];
+//  char pn[32];
 
   if (pinit)
     setaffinity(tid);
@@ -85,29 +90,17 @@ main(int ac, char** av)
 
   xmkdir(path);
 
-  int start[2];
-  if (pipe(start) < 0)
-    die("pipe");
+  mtenable_type(mtrace_record_ascope, "xv6-dirbench");
 
   u64 t0 = rdtsc();
   for(u32 i = 0; i < nthread; i++) {
     int pid = xfork();
     if (pid == 0) {
-      close(start[1]);
-      char token;
-      if (read(start[0], &token, 1) < 1)
-        die("read");
       bench(i, nloop, path);
     } else if (pid < 0)
       die("fork");
   }
 
-  mtenable_type(mtrace_record_ascope, "xv6-dirbench");
-
-  const char wakeup[256] = {};
-  if (write(start[1], wakeup, nthread) < nthread)
-    die("write");
-
   for (u32 i = 0; i < nthread; i++)
     xwait();
   u64 t1 = rdtsc();

bin/filebench.cc

@@ -74,6 +74,8 @@ main(int ac, char **av)
   if (ac > 3)
     path = av[3];
 
+  mtenable_type(mtrace_record_ascope, "xv6-filebench");
+
   // Setup shared file
   unlink(path);
   int fd = xcreat(path);
@@ -86,31 +88,17 @@ main(int ac, char **av)
   }
   close(fd);
 
-  int start[2];
-  if (pipe(start) < 0)
-    die("pipe");
-
   //mtenable("xv6-filebench");
   u64 t0 = rdtsc();
   for (int i = 0; i < nthread; i++) {
     int pid = xfork();
     if (pid == 0) {
-      close(start[1]);
-      char token;
-      if (read(start[0], &token, 1) < 1)
-        die("read");
       bench(i, nloop, path);
     }
     else if (pid < 0)
       die("fork");
   }
 
-  mtenable_type(mtrace_record_ascope, "xv6-filebench");
-
-  const char wakeup[256] = {};
-  if (write(start[1], wakeup, nthread) < nthread)
-    die("write");
-
   for (int i = 0; i < nthread; i++)
     xwait();
   u64 t1 = rdtsc();

bin/mapbench.cc

@@ -37,8 +37,8 @@ thr(void *arg)
 
   pthread_barrier_wait(&bar);
 
-  if (tid == 0)
-    mtenable_type(mtrace_record_ascope, "xv6-asharing");
+  // if (tid == 0)
+  //   mtenable_type(mtrace_record_ascope, "xv6-asharing");
 
   pthread_barrier_wait(&bar2);
 
@@ -75,6 +75,8 @@ main(int ac, char **av)
   if (ac > 2)
     niter = atoi(av[2]);
 
+  mtenable_type(mtrace_record_ascope, "xv6-asharing");
+
   pthread_t* tid = (pthread_t*) malloc(sizeof(*tid)*nthread);
 
   pthread_barrier_init(&bar, 0, nthread);