lfsr: add HOWTO and man page documentation
Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/HOWTO b/HOWTO
index 32e5d66..6d541af 100644
--- a/HOWTO
+++ b/HOWTO
@@ -753,6 +753,23 @@
will not be as complete as with random maps, this option is
disabled by default.
+random_generator=str Fio supports the following engines for generating
+ IO offsets for random IO:
+
+ tausworthe Strong 2^88 cycle random number generator
+ lfsr Linear feedback shift register generator
+
+ Tausworthe is a strong random number generator, but it
+ requires tracking on the side if we want to ensure that
+ blocks are only read or written once. LFSR guarantees
+ that we never generate the same offset twice, and it's
+ also less computationally expensive. It's not a true
+ random generator, however, though for IO purposes it's
+ typically good enough. LFSR only works with single
+ block sizes, not with workloads that use multiple block
+ sizes. If used with such a workload, fio may read or write
+ some blocks multiple times.
+
nice=int Run the job with the given nice value. See man nice(2).
prio=int Set the io priority value of this job. Linux limits us to