From: Jens Axboe <axboe@fb.com>
Date: Fri, 8 May 2015 15:19:25 +0000 (-0600)
Subject: random: document default seed value
X-Git-Tag: fio-2.2.9~43
X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=40fe5e7bf13fd7b99e26ed83623d3560a7ffdc8a;p=fio.git

random: document default seed value

Instead of hard coding this in the source, just set the default
value for the 'randseed' option'. Then it's visible when looked
up through --cmdhelp=randseed.

Also document that randrepeat is on by default in the HOWTO,
only the man page had this information.

Signed-off-by: Jens Axboe <axboe@fb.com>
---

diff --git a/HOWTO b/HOWTO
index 0808cc3a..d62d4089 100644
--- a/HOWTO
+++ b/HOWTO
@@ -435,6 +435,7 @@ unified_rw_reporting=bool	Fio normally reports statistics on a per
 
 randrepeat=bool	For random IO workloads, seed the generator in a predictable
 		way so that results are repeatable across repetitions.
+		Defaults to true.
 
 randseed=int	Seed the random number generators based on this seed value, to
 		be able to control what sequence of output is being generated.
diff --git a/init.c b/init.c
index fa50d3c6..ba5bf2fb 100644
--- a/init.c
+++ b/init.c
@@ -749,7 +749,7 @@ static int fixup_options(struct thread_data *td)
 	/*
 	 * If randseed is set, that overrides randrepeat
 	 */
-	if (td->o.rand_seed)
+	if (fio_option_is_set(&td->o, rand_seed))
 		td->o.rand_repeatable = 0;
 
 	if ((td->io_ops->flags & FIO_NOEXTEND) && td->o.file_append) {
@@ -966,14 +966,10 @@ static int setup_random_seeds(struct thread_data *td)
 	unsigned long seed;
 	unsigned int i;
 
-	if (!td->o.rand_repeatable && !td->o.rand_seed)
+	if (!td->o.rand_repeatable && !fio_option_is_set(&td->o, rand_seed))
 		return init_random_state(td, td->rand_seeds, sizeof(td->rand_seeds));
 
-	if (!td->o.rand_seed)
-		seed = 0x89;
-	else
-		seed = td->o.rand_seed;
-
+	seed = td->o.rand_seed;
 	for (i = 0; i < 4; i++)
 		seed *= 0x9e370001UL;
 
diff --git a/options.c b/options.c
index f21ed260..e306b28b 100644
--- a/options.c
+++ b/options.c
@@ -1845,6 +1845,7 @@ struct fio_option fio_options[FIO_MAX_OPTS] = {
 		.type	= FIO_OPT_STR_VAL,
 		.off1	= td_var_offset(rand_seed),
 		.help	= "Set the random generator seed value",
+		.def	= "0x89",
 		.parent = "rw",
 		.category = FIO_OPT_C_IO,
 		.group	= FIO_OPT_G_RANDOM,