Add an option "cgroup_nodelete" to not delete cgroups after job completion

o Add an option cgroup_nodelete to not remove cgroups created by fio after
  the job completion. This can help a user in inspecting various cgroup
  files after fio job completion.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/HOWTO b/HOWTO
index 6c7f05b..922db2f 100644
--- a/HOWTO
+++ b/HOWTO
@@ -1036,6 +1036,12 @@
 		the documentation that comes with the kernel, allowed values
 		are in the range of 100..1000.
 
+cgroup_nodelete=bool Normally fio will delete the cgroups it has created after
+		the job completion. To override this behavior and to leave
+		cgroups around after the job completion, set cgroup_nodelete=1.
+		This can be useful if one wants to inspect various cgroup
+		files after job completion. Default: false
+
 uid=int		Instead of running as the invoking user, set the user ID to
 		this value before the thread/process does any work.