Update io engine comments
Some were plain wrong, mainly because they were born through
copying an existing engine.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/engines/null.c b/engines/null.c
index 42a780a..6397ec0 100644
--- a/engines/null.c
+++ b/engines/null.c
@@ -1,5 +1,8 @@
/*
- * null engine - doesn't do any transfers. Used to test fio.
+ * null engine
+ *
+ * IO engine that doesn't do any real IO transfers, it just pretends to.
+ * The main purpose is to test fio itself.
*
*/
#include <stdio.h>