HOWTO: add rate example

Signed-off-by: Sitsofe Wheeler <sitsofe@yahoo.com>

diff --git a/HOWTO b/HOWTO
index 4be23f05755bf75b972622f5f6cfcf2a9d62c9da..742e0d26d15781fae80982aa8bd5b6af93bc0357 100644 (file)
--- a/HOWTO
+++ b/HOWTO
@@ -2039,6 +2039,11 @@ I/O rate
        suffix rules apply.  Comma-separated values may be specified for reads,
        writes, and trims as described in :option:`blocksize`.
 
+       For example, using `rate=1m,500k` would limit reads to 1MiB/sec and writes to
+       500KiB/sec.  Capping only reads or writes can be done with `rate=,500k` or
+       `rate=500k,` where the former will only limit writes (to 500KiB/sec) and the
+       latter will only limit reads.
+
 .. option:: rate_min=int[,int][,int]
 
        Tell fio to do whatever it can to maintain at least this bandwidth. Failing