'new_group' option

By default, jobs in a file are part of the same reporting group
unless seperated by a stone wall or if they define a group by
themselves (numjobs=x is used). Inserting a 'new_group' parameter
in a job description, will mark the start of a new reporting group.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/HOWTO b/HOWTO
index 8e873ea..d8c09d0 100644
--- a/HOWTO
+++ b/HOWTO
@@ -539,7 +539,13 @@
 
 stonewall	Wait for preceeding jobs in the job file to exit, before
 		starting this one. Can be used to insert serialization
-		points in the job file.
+		points in the job file. A stone wall also implies starting
+		a new reporting group.
+
+new_group	Start a new reporting group. If this option isn't given,
+		jobs in a file will be part of the same reporting group
+		unless seperated by a stone wall (or if it's a group
+		by itself, with the numjobs option).
 
 numjobs=int	Create the specified number of clones of this job. May be
 		used to setup a larger number of threads/processes doing