From fb66e77072fd075ac91cdae1623bcbdddd135a0c Mon Sep 17 00:00:00 2001
From: Julian Kunkel <JulianKunkel@users.noreply.github.com>
Date: Wed, 4 Nov 2020 13:47:35 +0000
Subject: [PATCH] Enable random seed to be stored. (#268)

---
 src/ior.c           | 22 +++++++++++-----------
 src/parse_options.c |  1 +
 2 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/src/ior.c b/src/ior.c
index 435fcb2..55733d5 100755
--- a/src/ior.c
+++ b/src/ior.c
@@ -1622,8 +1622,8 @@ static void ValidateTests(IOR_param_t * test)
         if (test->randomOffset && test->reorderTasks
             && test->filePerProc == FALSE)
                 ERR("random offset and constant reorder tasks specified with single-shared-file. Choose one and resubmit");
-        if (test->randomOffset && test->checkRead)
-                ERR("random offset not available with read check option (use write check)");
+        if (test->randomOffset && test->checkRead && test->randomSeed == -1)
+                ERR("random offset with read check option requires to set the random seed");
         if (test->randomOffset && test->storeFileOffset)
                 ERR("random offset not available with store file offset option)");
         if ((strcasecmp(test->api, "HDF5") == 0) && test->randomOffset)
@@ -1709,11 +1709,11 @@ IOR_offset_t *GetOffsetArrayRandom(IOR_param_t * test, int pretendRank, int acce
         IOR_offset_t fileSize;
         IOR_offset_t *offsetArray;
 
-        /* set up seed for random() */
-        if (access == WRITE || access == READ) {
+        /* set up seed, each process can determine which regions to access individually */
+        if (test->randomSeed == -1) {
                 test->randomSeed = seed = rand();
         } else {
-                seed = test->randomSeed;
+                seed = test->randomSeed + pretendRank;
         }
         srand(seed);
 
@@ -1723,16 +1723,16 @@ IOR_offset_t *GetOffsetArrayRandom(IOR_param_t * test, int pretendRank, int acce
         }
 
         /* count needed offsets (pass 1) */
-        for (i = 0; i < fileSize; i += test->transferSize) {
-                if (test->filePerProc == FALSE) {
+        if (test->filePerProc == FALSE) {
+          for (i = 0; i < fileSize; i += test->transferSize) {
                         // this counts which process get how many transferes in
                         // a shared file
                         if ((rand() % test->numTasks) == pretendRank) {
                                 offsets++;
                         }
-                } else {
-                        offsets++;
-                }
+          }
+        } else {
+          offsets += fileSize / test->transferSize;
         }
 
         /* setup empty array */
@@ -1749,7 +1749,7 @@ IOR_offset_t *GetOffsetArrayRandom(IOR_param_t * test, int pretendRank, int acce
                 }
         } else {
                 /* fill with offsets (pass 2) */
-                srand(seed);  /* need same seed  to get same transfers as counted in the beginning*/
+                srand(seed);  /* need same seedto get same transfers as counted in the beginning*/
                 for (i = 0; i < fileSize; i += test->transferSize) {
                         if ((rand() % test->numTasks) == pretendRank) {
                                 offsetArray[offsetCnt] = i;
diff --git a/src/parse_options.c b/src/parse_options.c
index c2b5b8c..87e3c91 100755
--- a/src/parse_options.c
+++ b/src/parse_options.c
@@ -433,6 +433,7 @@ option_help * createGlobalOptions(IOR_param_t * params){
     {'y', NULL,        "dualMount -- use dual mount points for a filesystem", OPTION_FLAG, 'd', & params->dualMount},
     {'Y', NULL,        "fsyncPerWrite -- perform sync operation after every write operation", OPTION_FLAG, 'd', & params->fsyncPerWrite},
     {'z', NULL,        "randomOffset -- access is to random, not sequential, offsets within a file", OPTION_FLAG, 'd', & params->randomOffset},
+    {0, "random-offset-seed",        "The seed for -z", OPTION_OPTIONAL_ARGUMENT, 'd', & params->randomSeed},
     {'Z', NULL,        "reorderTasksRandom -- changes task ordering to random ordering for readback", OPTION_FLAG, 'd', & params->reorderTasksRandom},
     {0, "warningAsErrors",        "Any warning should lead to an error.", OPTION_FLAG, 'd', & params->warningAsErrors},
     {.help="  -O summaryFile=FILE                 -- store result data into this file", .arg = OPTION_OPTIONAL_ARGUMENT},