Reseed random generator for loop/time based runs
Then we get repeatable 2nd/3rd/etc runs. This is important
if the file layout was random, otherwise subsequent runs will
get very different results.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/init.c b/init.c
index 80d098d..8deedcc 100644
--- a/init.c
+++ b/init.c
@@ -408,13 +408,32 @@
return 1;
}
+void td_fill_rand_seeds(struct thread_data *td)
+{
+ os_random_seed(td->rand_seeds[0], &td->bsrange_state);
+ os_random_seed(td->rand_seeds[1], &td->verify_state);
+ os_random_seed(td->rand_seeds[2], &td->rwmix_state);
+
+ if (td->o.file_service_type == FIO_FSERVICE_RANDOM)
+ os_random_seed(td->rand_seeds[3], &td->next_file_state);
+
+ os_random_seed(td->rand_seeds[5], &td->file_size_state);
+
+ if (!td_random(td))
+ return;
+
+ if (td->o.rand_repeatable)
+ td->rand_seeds[4] = FIO_RANDSEED * td->thread_number;
+
+ os_random_seed(td->rand_seeds[4], &td->random_state);
+}
+
/*
* Initialize the various random states we need (random io, block size ranges,
* read/write mix, etc).
*/
static int init_random_state(struct thread_data *td)
{
- unsigned long seeds[6];
int fd;
fd = open("/dev/urandom", O_RDONLY);
@@ -423,30 +442,15 @@
return 1;
}
- if (read(fd, seeds, sizeof(seeds)) < (int) sizeof(seeds)) {
+ if (read(fd, td->rand_seeds, sizeof(td->rand_seeds)) <
+ (int) sizeof(td->rand_seeds)) {
td_verror(td, EIO, "read");
close(fd);
return 1;
}
close(fd);
-
- os_random_seed(seeds[0], &td->bsrange_state);
- os_random_seed(seeds[1], &td->verify_state);
- os_random_seed(seeds[2], &td->rwmix_state);
-
- if (td->o.file_service_type == FIO_FSERVICE_RANDOM)
- os_random_seed(seeds[3], &td->next_file_state);
-
- os_random_seed(seeds[5], &td->file_size_state);
-
- if (!td_random(td))
- return 0;
-
- if (td->o.rand_repeatable)
- seeds[4] = FIO_RANDSEED * td->thread_number;
-
- os_random_seed(seeds[4], &td->random_state);
+ td_fill_rand_seeds(td);
return 0;
}