top command is by collection, not by database, i believe

Author: dwight

source/reference/command/top.txt

@@ -7,7 +7,7 @@ top
 .. dbcommand:: top
 
    The :dbcommand:`top` command is an administrative command which 
-   returns raw usage of each database,
+   returns usage statistics for each collection.
    and provides amount of time, in microseconds, used and a count of
    operations for the following event types:
 
@@ -28,3 +28,50 @@ top
    .. code-block:: javascript
 
       { top: 1 }
+
+   Shell example:
+
+   .. code-block:: javascript
+
+      > db.adminCommand("top")
+      {    
+	"totals" : {
+                "test.foo" : {
+                        "total" : {
+                                "time" : 305277,
+                                "count" : 2825
+                        },
+                        "readLock" : {
+                                "time" : 305264,
+                                "count" : 2824
+                        },
+                        "writeLock" : {
+                                "time" : 13,
+                                "count" : 1
+                        },
+                        "queries" : {
+                                "time" : 305264,
+                                "count" : 2824
+                        },
+                        "getmore" : {
+                                "time" : 0,
+                                "count" : 0
+                        },
+                        "insert" : {
+                                "time" : 0,
+                                "count" : 0
+                        },
+                        "update" : {
+                                "time" : 0,
+                                "count" : 0
+                        },
+                        "remove" : {
+                                "time" : 0,
+                                "count" : 0
+                        },
+                        "commands" : {
+                                "time" : 0,
+                                "count" : 0
+                        }
+		}
+	}