Rev 3901: Tweak the number of blank spaces up just a tad. in http://bzr.arbash-meinel.com/branches/bzr/brisbane/gc_delta_index_room

[John Arbash Meinel]

At http://bzr.arbash-meinel.com/branches/bzr/brisbane/gc_delta_index_room

------------------------------------------------------------
revno: 3901
revision-id: john at arbash-meinel.com-20090319061002-bcf6ikop39ap4s6w
parent: john at arbash-meinel.com-20090319060153-p0e7qedqdq9vd8iq
committer: John Arbash Meinel <john at arbash-meinel.com>
branch nick: gc_delta_index_room
timestamp: Thu 2009-03-19 01:10:02 -0500
message:
  Tweak the number of blank spaces up just a tad.
  It seems that setting it to 8 doesn't see a net gain. There is a slight
  improvement in the number of readjustments done, but that is counteracted
  by the make_delta time.
-------------- next part --------------
=== modified file 'bzrlib/diff-delta.c'
--- a/bzrlib/diff-delta.c	2009-03-19 06:01:53 +0000
+++ b/bzrlib/diff-delta.c	2009-03-19 06:10:02 +0000
@@ -25,10 +25,11 @@
 #define RABIN_SHIFT 23
 #define RABIN_WINDOW 16
 
-/* The hash map is sized to put 4 entries per bucket, this gives us 3 blank
- * spaces.
+/* The hash map is sized to put 4 entries per bucket, this gives us ~even room
+ * for more data. Tweaking this number above 4 doesn't seem to help much,
+ * anyway.
  */
-#define EXTRA_NULLS 3
+#define EXTRA_NULLS 4
 
 static const unsigned int T[256] = {
     0x00000000, 0xab59b4d1, 0x56b369a2, 0xfdeadd73, 0x063f6795, 0xad66d344,