[svn-r4964] Purpose:

    Change default actions.
Description:
    Change the default maximum number of processes (-P) to use all processes
    instead of just 1 (old default).  Someone most likely wants to test
    the I/O performance with all processes involved.
    Also starts performance measurement with maximum number of processes
    and decrement it with each loop.  If the performance measurement
    needs to restart, it can run with fewer processes if those loops
    have completed.
Platforms tested:
    modi4 and eirene.

1 files changed, 23 insertions, 7 deletions

diff --git a/perform/pio_perf.c b/perform/pio_perf.c
index 6da8aae..4e2da0e 100644
--- a/perform/pio_perf.c
+++ b/perform/pio_perf.c
@@ -79,6 +79,8 @@
 #define MB_PER_SEC(bytes,t) (((bytes) / ONE_MB) / t)
 
 /* global variables */
+int         comm_world_rank_g;  /* my rank in MPI_COMM_RANK */
+int         comm_world_nprocs_g;/* num. of processes of MPI_COMM_WORLD */
 MPI_Comm    pio_comm_g;         /* Communicator to run the PIO          */
 int         pio_mpi_rank_g;     /* MPI rank of pio_comm_g               */
 int         pio_mpi_nprocs_g;   /* Number of processes of pio_comm_g    */
@@ -242,14 +244,14 @@ static void usage(const char *prog);
 int
 main(int argc, char **argv)
 {
-    int world_size, ret;
+    int ret;
     int exit_value = EXIT_SUCCESS;
     FILE *output = stdout;
     struct options *opts = NULL;
 
     /* initialize MPI and get the maximum num of processors we started with */
     MPI_Init(&argc, &argv);
-    ret = MPI_Comm_size(MPI_COMM_WORLD, &world_size);
+    ret = MPI_Comm_size(MPI_COMM_WORLD, &comm_world_nprocs_g);
 
     if (ret != MPI_SUCCESS) {
         fprintf(stderr, "%s: MPI_Comm_size call failed\n", progname);
@@ -262,6 +264,19 @@ main(int argc, char **argv)
         exit_value = EXIT_FAILURE;
         goto finish;
     }
+    ret = MPI_Comm_rank(MPI_COMM_WORLD, &comm_world_rank_g);
+
+    if (ret != MPI_SUCCESS) {
+        fprintf(stderr, "%s: MPI_Comm_rank call failed\n", progname);
+
+        if (ret == MPI_ERR_COMM)
+            fprintf(stderr, "invalid MPI communicator\n");
+        else
+            fprintf(stderr, "invalid argument\n");
+
+        exit_value = EXIT_FAILURE;
+        goto finish;
+    }
 
     pio_comm_g = MPI_COMM_WORLD;
 
@@ -334,9 +349,10 @@ run_test_loop(FILE *output, struct options *opts)
     parms.num_dsets = opts->num_dsets;
     parms.num_iters = opts->num_iters;
 
-    /* multiply the maximum number of processors by 2 for each loop iter */
-    for (num_procs = opts->min_num_procs;
-            num_procs <= opts->max_num_procs; num_procs <<= 1) {
+    /* start with max_num_procs and decrement it by half for each loop. */
+    /* if performance needs restart, fewer processes may be needed. */
+    for (num_procs = opts->max_num_procs;
+            num_procs >= opts->min_num_procs; num_procs >>= 1) {
         register long buf_size;
 
         parms.num_procs = num_procs;
@@ -791,7 +807,7 @@ parse_command_line(int argc, char *argv[])
     cl_opts->num_dsets = 1;
     cl_opts->num_files = 1;
     cl_opts->num_iters = 1;
-    cl_opts->max_num_procs = 1;
+    cl_opts->max_num_procs = comm_world_nprocs_g;
     cl_opts->min_num_procs = 1;
     cl_opts->max_xfer_size = 1 * ONE_MB;
     cl_opts->min_xfer_size = 128 * ONE_KB;
@@ -938,7 +954,7 @@ usage(const char *prog)
         fprintf(stdout, "     -i, --num-iterations        Number of iterations to perform [default: 1]\n");
         fprintf(stdout, "     -m, --mpiio                 Run MPI/IO performance test\n");
         fprintf(stdout, "     -o F, --output=F            Output raw data into file F [default: none]\n");
-        fprintf(stdout, "     -P N, --max-num-processes=N Maximum number of processes to use [default: 1]\n");
+        fprintf(stdout, "     -P N, --max-num-processes=N Maximum number of processes to use [default: all MPI_COMM_WORLD processes ]\n");
         fprintf(stdout, "     -p N, --min-num-processes=N Minimum number of processes to use [default: 1]\n");
         fprintf(stdout, "     -r, --raw                   Run raw (UNIX) performance test\n");
         fprintf(stdout, "     -X S, --max-xfer-size=S     Maximum transfer buffer size [default: 1M]\n");