From 0ffec67d2b35f60cd99cfb8307a2f342414c3bcc Mon Sep 17 00:00:00 2001
From: John Bent <johnbent@AMR-U535110L001.ad.seagate.com>
Date: Sun, 28 Jul 2019 10:25:42 -0600
Subject: [PATCH] Following Julian's suggestion about better naming

---
 src/ior.c    | 18 +++++++-----------
 src/ior.h    |  2 +-
 src/mdtest.c |  6 ++++--
 3 files changed, 12 insertions(+), 14 deletions(-)

diff --git a/src/ior.c b/src/ior.c
index bb2b4c2..64530fd 100755
--- a/src/ior.c
+++ b/src/ior.c
@@ -939,7 +939,7 @@ static void InitTests(IOR_test_t *tests, MPI_Comm com)
                 params->testComm = com;
                 params->nodes = params->numTasks / tasksPerNode;
                 params->tasksPerNode = tasksPerNode;
-                params->packedTasks = QueryNodeMapping(com);
+                params->tasksBlockMapping = QueryNodeMapping(com);
                 if (params->numTasks == 0) {
                   params->numTasks = size;
                 }
@@ -1361,11 +1361,9 @@ static void TestIoSys(IOR_test_t *test)
                         }
                         if (params->reorderTasks) {
                                 /* move two nodes away from writing node */
-                                int shift = 1;
-                                if (params->packedTasks) {
-                                    shift = params->tasksPerNode;
-                                } else {
-                                    shift = 1;
+                                int shift = 1; /* assume a by-node (round-robin) mapping of tasks to nodes */
+                                if (params->tasksBlockMapping) {
+                                    shift = params->tasksPerNode; /* switch to by-slot (contiguous block) mapping */
                                 }
                                 rankOffset = (2 * shift) % params->numTasks;
                         }
@@ -1403,11 +1401,9 @@ static void TestIoSys(IOR_test_t *test)
                         /* Constant process offset reading */
                         if (params->reorderTasks) {
                                 /* move one node away from writing node */ 
-                                int shift = 1;
-                                if (params->packedTasks) {
-                                    shift=params->tasksPerNode;
-                                } else {
-                                    shift=1;
+                                int shift = 1; /* assume a by-node (round-robin) mapping of tasks to nodes */
+                                if (params->tasksBlockMapping) {
+                                    shift=params->tasksPerNode; /* switch to a by-slot (contiguous block) mapping */
                                 }
                                 rankOffset = (params->taskPerNodeOffset * shift) % params->numTasks;
                         }
diff --git a/src/ior.h b/src/ior.h
index 2ea6c05..e245b08 100755
--- a/src/ior.h
+++ b/src/ior.h
@@ -100,7 +100,7 @@ typedef struct
     int numTasks;                    /* number of tasks for test */
     int nodes;                       /* number of nodes for test */
     int tasksPerNode;                /* number of tasks per node */
-    int packedTasks;                 /* are the tasks round-robin across nodes or are they packed tightly*/ 
+    int tasksBlockMapping;           /* are the tasks in contiguous blocks across nodes or round-robin */ 
     int repetitions;                 /* number of repetitions of test */
     int repCounter;                  /* rep counter */
     int multiFile;                   /* multiple files */
diff --git a/src/mdtest.c b/src/mdtest.c
index e35a20e..0005c0a 100644
--- a/src/mdtest.c
+++ b/src/mdtest.c
@@ -2067,11 +2067,13 @@ mdtest_results_t * mdtest_run(int argc, char **argv, MPI_Comm world_com, FILE *
     VERBOSE(3,-1,"main (before display_freespace): testdirpath is '%s'", testdirpath );
 
     if (rank == 0) display_freespace(testdirpath);
-    int packedByNode = QueryNodeMapping(testComm);
+    int tasksBlockMapping = QueryNodeMapping(testComm);
 
     /* set the shift to mimic IOR and shift by procs per node */
     if (nstride > 0) {
-        if ( nodeCount > 1 && packedByNode ) {
+        if ( nodeCount > 1 && tasksBlockMapping ) {
+            /* the user set the stride presumably to get the consumer tasks on a different node than the producer tasks
+               however, if the mpirun scheduler placed the tasks by-slot (in a contiguous block) then we need to adjust the shift by ppn */
             nstride *= tasksPerNode;
         }
         VERBOSE(0,5,"Shifting ranks by %d for each phase.", nstride);