Fixed/changes the memory graph in collection.cgi to work even if `page cache'

and/or `buffer cache' is undefined.

diff --git a/contrib/collection.cgi b/contrib/collection.cgi
index 63b1563..51e187d 100755 (executable)
--- a/contrib/collection.cgi
+++ b/contrib/collection.cgi
@@ -303,8 +303,10 @@ our $GraphDefs;
                        'DEF:free_max={file}:free:MAX',
                        'DEF:buffers_max={file}:buffers:MAX',
                        'DEF:cached_max={file}:cached:MAX',
-                       'CDEF:free_cached_buffers_used=free_avg,cached_avg,+,buffers_avg,+,used_avg,+',
-                       'CDEF:cached_buffers_used=cached_avg,buffers_avg,+,used_avg,+',
+                       'CDEF:cached_avg_nn=cached_avg,UN,0,cached_avg,IF',
+                       'CDEF:buffers_avg_nn=buffers_avg,UN,0,buffers_avg,IF',
+                       'CDEF:free_cached_buffers_used=free_avg,cached_avg_nn,+,buffers_avg_nn,+,used_avg,+',
+                       'CDEF:cached_buffers_used=cached_avg,buffers_avg_nn,+,used_avg,+',
                        'CDEF:buffers_used=buffers_avg,used_avg,+',
                        "AREA:free_cached_buffers_used#$HalfGreen",
                        "AREA:cached_buffers_used#$HalfBlue",