Use a fix timer in the injection loop

Doesn't make any difference

swiftmpistepsim.c

@@ -38,6 +38,9 @@ static int verbose = 0;
 /* Attempt to keep original injection time differences. */
 static int usetics = 1;
 
+/* The wait between injections, nanosecs. */
+static long long waitns = 10000;
+
 /* Integer types of send and recv tasks, must match log. */
 static const int task_type_send = 22;
 static const int task_type_recv = 23;
@@ -81,38 +84,16 @@ static void *inject_thread(void *arg) {
   ticks looptics = 0;
   double deadtime = 0.0;
 
+  struct timespec sleep;
+  sleep.tv_sec = 0;
+
   while (ind_req < nr_reqs) {
     struct mpiuse_log_entry *log = reqs_queue[ind_req];
 
     if (usetics) {
-      /* Expect time between this request and the previous one. */
-      ticks dt = log->tic - basetic;
-      basetic = log->tic;
-
-      /* We guess some time below which we should not attempt to wait,
-       * otherwise we'll start to overrun, and just inject the next call if we
-       * are below that (we time the ticks this loop takes without any waiting
-       * and use that). Otherwise we wait a while. Note we need to convert the
-       * ticks of the log file into nanoseconds, that requires the original
-       * CPU frequency. */
-      if (dt > looptics) {
-        struct timespec sleep;
-        sleep.tv_sec = 0;
-
-        /* Remember to be fair and remove the looptics, then convert to
-         * nanoseconds. */
-        double ns = (double)(dt - looptics) / log_clocks_cpufreq * 1.0e9;
-        if (ns < 1.0e9) {
-          sleep.tv_nsec = (long)ns;
-        } else {
-          /* Wait more than one second. Must be an error, but complain and
-           * continue.  */
-          sleep.tv_nsec = (long)1.0e9;
-          message("wait greater than one second");
-        }
-        nanosleep(&sleep, NULL);
-        deadtime += sleep.tv_nsec;
-      }
+      sleep.tv_nsec = waitns;
+      nanosleep(&sleep, NULL);
+      deadtime += sleep.tv_nsec;
     }
 
     /* Initialise new log elements. */
@@ -151,7 +132,8 @@ static void *inject_thread(void *arg) {
     /* Set looptics on the first pass. Assumes MPI_Isend and MPI_Irecv are
      * equally timed. */
     if (looptics == 0 && usetics) {
-      looptics = getticks() - starttics;
+        /* Not well matched, so try a lower value. */
+        looptics = (getticks() - starttics) / 4;
       if (verbose)
         message("injection loop took %.3f %s.", clocks_from_ticks(looptics),
                 clocks_getunit());
@@ -355,9 +337,10 @@ static void pick_logs(void) {
  * @brief usage help.
  */
 static void usage(char *argv[]) {
-  fprintf(stderr, "Usage: %s [-vf] SWIFT_mpiuse-log-file.dat logfile.dat\n",
-          argv[0]);
-  fprintf(stderr, " options: -v verbose, -f fast injections\n");
+  fprintf(stderr, "Usage: %s [-vf] [-n nanosec] SWIFT_mpiuse-log-file.dat "
+          "logfile.dat\n", argv[0]);
+  fprintf(stderr, " options: -v verbose, -f fast injections, "
+          "-n nanoseconds to wait\n");
   fflush(stderr);
 }
 
@@ -383,7 +366,7 @@ int main(int argc, char *argv[]) {
   /* Handle the command-line, we expect a mpiuse data file to read and various
    * options. */
   int opt;
-  while ((opt = getopt(argc, argv, "vf")) != -1) {
+  while ((opt = getopt(argc, argv, "vfn:")) != -1) {
     switch (opt) {
       case 'f':
         usetics = 0;
@@ -391,6 +374,9 @@ int main(int argc, char *argv[]) {
       case 'v':
         verbose = 1;
         break;
+      case 'n':
+        waitns = atoll(optarg);
+        break;
       default:
         if (myrank == 0) usage(argv);
         return 1;
@@ -428,6 +414,7 @@ int main(int argc, char *argv[]) {
   if (myrank == 0) {
     message("Start of MPI tests");
     message("==================");
+    message("injecting fixed waits of %lld ns", waitns);
   }
 
   /* Make three threads, one for injecting tasks and two to check for