fcoll/vulcan: Remove unnecessary calls to write

Identify the index of each aggregator process in order to restrict the call to write_init function by the specific aggregator.

Signed-off-by: raafatfeki <fekiraafat@gmail.com>

ompi/mca/fcoll/vulcan/fcoll_vulcan_file_write_all.c

@@ -36,7 +36,7 @@
 #define DEBUG_ON 0
 #define FCOLL_VULCAN_SHUFFLE_TAG   123
 #define INIT_LEN 10
-
+#define NOT_AGGR_INDEX -1
 
 /*Used for loading file-offsets per aggregator*/
 typedef struct mca_io_ompio_local_io_array{
@@ -538,6 +538,7 @@ int mca_fcoll_vulcan_file_write_all (mca_io_ompio_file_t *fh,
 #endif
     }    
 
+    int aggr_index = NOT_AGGR_INDEX;
     reqs1 = (ompi_request_t **)malloc ((fh->f_procs_per_group + 1 )*vulcan_num_io_procs *sizeof(ompi_request_t *));
     reqs2 = (ompi_request_t **)malloc ((fh->f_procs_per_group + 1 )*vulcan_num_io_procs *sizeof(ompi_request_t *));
     if ( NULL == reqs1 || NULL == reqs2 ) {
@@ -561,6 +562,11 @@ int mca_fcoll_vulcan_file_write_all (mca_io_ompio_file_t *fh,
         for ( i=0; i<vulcan_num_io_procs; i++ ) {
             ret = shuffle_init ( 0, cycles, aggregators[i], fh->f_rank, aggr_data[i], 
                                  &curr_reqs[i*(fh->f_procs_per_group + 1)] );
+
+            if(aggregators[i] == fh->f_rank) {
+                aggr_index = i;
+            }
+
             if ( OMPI_SUCCESS != ret ) {
                 goto exit;
             }
@@ -589,15 +595,15 @@ int mca_fcoll_vulcan_file_write_all (mca_io_ompio_file_t *fh,
         }
 	
         
-        /* Write data for iteration i-1 */
+        /* Write data for iteration i-1 only by an aggregator*/
-        for ( i=0; i<vulcan_num_io_procs; i++ ) {
+        if(NOT_AGGR_INDEX != aggr_index) {
 #if OMPIO_FCOLL_WANT_TIME_BREAKDOWN
             start_write_time = MPI_Wtime();
 #endif
-            ret = write_init (fh, aggregators[i], aggr_data[i], write_chunksize );
+            ret = write_init (fh, aggregators[aggr_index], aggr_data[aggr_index], write_chunksize );
             if (OMPI_SUCCESS != ret){
                 goto exit;
-            }            
+            }
 #if OMPIO_FCOLL_WANT_TIME_BREAKDOWN
             end_write_time = MPI_Wtime();
             write_time += end_write_time - start_write_time;
@@ -619,14 +625,14 @@ int mca_fcoll_vulcan_file_write_all (mca_io_ompio_file_t *fh,
         }
         
         /* Write data for iteration i=cycles-1 */
-        for ( i=0; i<vulcan_num_io_procs; i++ ) {
+        if(NOT_AGGR_INDEX != aggr_index) {
 #if OMPIO_FCOLL_WANT_TIME_BREAKDOWN
             start_write_time = MPI_Wtime();
 #endif
-            ret = write_init (fh, aggregators[i], aggr_data[i], write_chunksize );
+            ret = write_init (fh, aggregators[aggr_index], aggr_data[aggr_index], write_chunksize );
             if (OMPI_SUCCESS != ret){
                 goto exit;
-            }                    
+            }
 #if OMPIO_FCOLL_WANT_TIME_BREAKDOWN
             end_write_time = MPI_Wtime();
             write_time += end_write_time - start_write_time;
@@ -728,7 +734,7 @@ static int write_init (mca_io_ompio_file_t *fh, int aggregator, mca_io_ompio_agg
     int last_pos=0;
         
 
-    if ( aggregator == fh->f_rank && aggr_data->prev_num_io_entries) {
+    if (aggr_data->prev_num_io_entries) {
         while ( aggr_data->prev_bytes_to_write > 0 ) {                    
             aggr_data->prev_bytes_to_write -= mca_fcoll_vulcan_split_iov_array (fh, aggr_data->prev_io_array, 
                                                                                       aggr_data->prev_num_io_entries,