Allow ranges of CPUs in cpus_allowed option

For a larger number of CPUs, it's a bit of a bother having to set
each one individually. Plus, you typically want to bind to a range of
CPUs, to keep the job core local (or whatever your preference). So extend
cpus_allowed to take ranges of CPU numbers as well. Now you can do:

cpus_allowed=0-7

and have your job confined to CPUs 0 through 7.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/HOWTO b/HOWTO
index 5a55c1a..7bd71a9 100644
--- a/HOWTO
+++ b/HOWTO
@@ -590,7 +590,9 @@
 
 cpus_allowed=str Controls the same options as cpumask, but it allows a text
 		setting of the permitted CPUs instead. So to use CPUs 1 and
-		5, you would specify cpus_allowed=1,5.
+		5, you would specify cpus_allowed=1,5. This options also
+		allows a range of CPUs. Say you wanted a binding to CPUs
+		1, 5, and 8-15, you would set cpus_allowed=1,5,8-15.
 
 startdelay=time	Start this job the specified number of seconds after fio
 		has started. Only useful if the job file contains several