Switch to using our internal Tausworthe based random generator for offsets
It's both faster and more exhaustive than what is available on
glibc on my test systems. So no downsides, and the upside of having
the same offset generator across all platforms.
This will change the random series, so could alter performance for
your workload since the pattern will be different in sequence. There's
an option to revert to the OS generator, you can add use_us_rand=1
on your job files to retain the old generator offsets.
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
diff --git a/fio.1 b/fio.1
index a8c0027..0ced604 100644
--- a/fio.1
+++ b/fio.1
@@ -214,6 +214,12 @@
Seed the random number generator in a predictable way so results are repeatable
across runs. Default: true.
.TP
+.BI use_os_rand \fR=\fPbool
+Fio can either use the random generator supplied by the OS to generator random
+offsets, or it can use it's own internal generator (based on Tausworthe).
+Default is to use the internal generator, which is often of better quality and
+faster. Default: false.
+.TP
.BI fallocate \fR=\fPbool
By default, fio will use fallocate() to advise the system of the size of the
file we are going to write. This can be turned off with fallocate=0. May not