Add usage note.

7d74effc · Raymond Hettinger · 0c9050c2 · 7d74effc
Commit 7d74effc authored Jun 04, 2012 by Raymond Hettinger
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Doc/library/functools.rst Doc/library/functools.rst +3 -2

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--- a/Doc/library/functools.rst
+++ b/Doc/library/functools.rst
@@ -49,8 +49,9 @@ The :mod:`functools` module defines the following functions:
   Since a dictionary is used to cache results, the positional and keyword
   arguments to the function must be hashable.

-   If *maxsize* is set to None, the LRU feature is disabled and the cache
-   can grow without bound.
+   If *maxsize* is set to None, the LRU feature is disabled and the cache can
+   grow without bound.  The LRU feature performs best when *maxsize* is a
+   power-of-two.

   If *typed* is set to True, function arguments of different types will be
   cached separately.  For example, ``f(3)`` and ``f(3.0)`` will be treated