Enable request flow under Poisson process

[fio.git] / backend.c

diff --git a/backend.c b/backend.c
index 0a42da3ec440673d741da6ce56e235e997caf1b6..7a030ebbbe40e2f3a10347376d1dd26eb045479c 100644 (file)
--- a/backend.c
+++ b/backend.c
@@ -35,6 +35,7 @@
 #include <sys/wait.h>
 #include <sys/ipc.h>
 #include <sys/mman.h>
+#include <math.h>
 
 #include "fio.h"
 #ifndef FIO_NO_HAVE_SHM_H
@@ -775,12 +776,18 @@ static int io_complete_bytes_exceeded(struct thread_data *td)
  */
 static long long usec_for_io(struct thread_data *td, enum fio_ddir ddir)
 {
-       uint64_t secs, remainder, bps, bytes;
+       uint64_t secs, remainder, bps, bytes, iops;
 
        assert(!(td->flags & TD_F_CHILD));
        bytes = td->rate_io_issue_bytes[ddir];
        bps = td->rate_bps[ddir];
-       if (bps) {
+
+       if (td->o.poisson_request) {
+               iops = bps / td->o.bs[ddir];
+               td->last_usec += (long long)(1000000 / iops) *
+                       (-logf(((float)rand() + 1) / ((float)RAND_MAX + 1)));
+               return td->last_usec;
+       } else if (bps) {
                secs = bytes / bps;
                remainder = bytes % bps;
                return remainder * 1000000 / bps + secs * 1000000;