Tweak filebench to start mtrace after setup

846a4116 · Austin Clements · cba5ff86 · 846a4116
--- a/bin/filebench.cc
+++ b/bin/filebench.cc
@@ -20,7 +20,10 @@
 static const bool pinit = true;
-static char chunkbuf[CHUNKSZ];
+// XXX(austin) Totally lame.  Align chunkbuf so that we don't have to
+// COW fault on a mapped file page in bench.
+static char chunkbuf[CHUNKSZ]
+__attribute__((aligned(4096)));
 static void
 bench(int tid, int nloop, const char* path)
@@ -83,16 +86,31 @@ main(int ac, char **av)
  }
  close(fd);
-  mtenable("xv6-filebench");
+  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)
+    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();