Usleep feature added according to Nathan's suggestions.

doc/USER_GUIDE

@@ -170,6 +170,8 @@ GENERAL:
                            NOTE: it does not delay before a check write or
                                  check read
 
+  * interIODelay         - this time in us (microseconds) after each I/O simulates computing time.
+
   * outlierThreshold     - gives warning if any task is more than this number
                            of seconds from the mean of all participating tasks.
                            If so, the task is identified, its time (start,

src/ior.c

@@ -1839,11 +1839,17 @@ static IOR_offset_t WriteOrReadSingle(IOR_offset_t pairCnt, IOR_offset_t *offset
                   backend->xfer(access, fd, buffer, transfer, test);
           if (amtXferred != transfer)
                   ERR("cannot write to file");
+          if (test->interIODelay > 0){
+            usleep(test->interIODelay);
+          }
   } else if (access == READ) {
           amtXferred =
                   backend->xfer(access, fd, buffer, transfer, test);
           if (amtXferred != transfer)
                   ERR("cannot read from file");
+          if (test->interIODelay > 0){
+            usleep(test->interIODelay);
+          }
   } else if (access == WRITECHECK) {
           memset(checkBuffer, 'a', transfer);
 

src/ior.h

@@ -100,6 +100,7 @@ typedef struct
     int repCounter;                  /* rep counter */
     int multiFile;                   /* multiple files */
     int interTestDelay;              /* delay between reps in seconds */
+    int interIODelay;                /* delay after each I/O in us */
     int open;                        /* flag for writing or reading */
     int readFile;                    /* read of existing file */
     int writeFile;                   /* write of file */

src/parse_options.c

@@ -167,6 +167,8 @@ void DecodeDirective(char *line, IOR_param_t *params)
                 params->repetitions = atoi(value);
         } else if (strcasecmp(option, "intertestdelay") == 0) {
                 params->interTestDelay = atoi(value);
+        } else if (strcasecmp(option, "interiodelay") == 0) {
+                params->interIODelay = atoi(value);
         } else if (strcasecmp(option, "readfile") == 0) {
                 params->readFile = atoi(value);
         } else if (strcasecmp(option, "writefile") == 0) {