config: clarify compression defaults

* Clarify that core.compression provides a system-wide default to
  other compression parameters.

* Explain that the default for pack.compression, -1, is "a default
  compromise between speed and compression (currently equivalent
  to level 6)" according to zlib.h.

Signed-off-by: Brian Downing <bdowning@lavos.net>
Acked-by: Nicolas Pitre <nico@cam.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/Documentation/config.txt b/Documentation/config.txt
index 95656526c45de083e541b3ecfe51ed5c234f9b87..83bc33c421f666367a49da03481608b0638c255e 100644 (file)
--- a/Documentation/config.txt
+++ b/Documentation/config.txt
@@ -226,6 +226,8 @@ core.compression::
        An integer -1..9, indicating a default compression level.
        -1 is the zlib default. 0 means no compression,
        and 1..9 are various speed/size tradeoffs, 9 being slowest.
+       If set, this provides a default to other compression variables,
+       such as 'core.loosecompression' and 'pack.compression'.
 
 core.loosecompression::
        An integer -1..9, indicating the compression level for objects that
@@ -622,7 +624,9 @@ pack.compression::
        in a pack file. -1 is the zlib default. 0 means no
        compression, and 1..9 are various speed/size tradeoffs, 9 being
        slowest.  If not set,  defaults to core.compression.  If that is
-       not set,  defaults to -1.
+       not set,  defaults to -1, the zlib default, which is "a default
+       compromise between speed and compression (currently equivalent
+       to level 6)."
 
 pack.deltaCacheSize::
        The maximum memory in bytes used for caching deltas in