Add support for modifying the randomness of a workload
Fio supports random or sequential IO, or random IO with a number of
sequential IOs in between. The percentage_random options allows
more fine grained control over this. It defaults to 100, which would
make any random workload still purely random. If set below 100,
there will be some percentage of sequential IOs. This happens randomly,
but at the specified percentages.
The percentage_sequential option is just the complement of that, it
is guaranteed that:
percentage_sequential + percentage_random == 100%
The later setting has priority, each will adjust the other.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/HOWTO b/HOWTO
index 6445348..8211c3b 100644
--- a/HOWTO
+++ b/HOWTO
@@ -766,6 +766,17 @@
random_distribution=zipf:1.2 as the option. If a non-uniform
model is used, fio will disable use of the random map.
+percentage_random=int For a random workload, set how big a percentage should
+ be random. This defaults to 100%, in which case the workload
+ is fully random. It can be set from anywhere from 0 to 100.
+ Setting it to 0 would make the workload fully sequential. Any
+ setting in between will result in a random mix of sequential
+ and random IO, at the given percentages.
+
+percentage_sequential=int See percentage_random. It is guaranteed that
+ they add up to 100. The later setting has priority, each
+ will adjust the other.
+
norandommap Normally fio will cover every block of the file when doing
random IO. If this option is given, fio will just get a
new random offset without looking at past io history. This