Issue #15055: update dictnotes.txt. Patch by Mark Shannon.
diff --git a/Objects/dictnotes.txt b/Objects/dictnotes.txt
index a38b052..f89720c 100644
--- a/Objects/dictnotes.txt
+++ b/Objects/dictnotes.txt
@@ -70,42 +70,8 @@
Tunable Dictionary Parameters
-----------------------------
-* PyDict_STARTSIZE. Starting size of dict (unless an instance dict).
- Currently set to 8. Must be a power of two.
- New dicts have to zero-out every cell.
- Increasing improves the sparseness of small dictionaries but costs
- time to read in the additional cache lines if they are not already
- in cache. That case is common when keyword arguments are passed.
- Prior to version 3.3, PyDict_MINSIZE was used as the starting size
- of a new dict.
-
-* PyDict_MINSIZE. Minimum size of a dict.
- Currently set to 4 (to keep instance dicts small).
- Must be a power of two. Prior to version 3.3, PyDict_MINSIZE was
- set to 8.
-
-* USABLE_FRACTION. Maximum dictionary load in PyDict_SetItem.
- Currently set to 2/3. Increasing this ratio makes dictionaries more
- dense resulting in more collisions. Decreasing it improves sparseness
- at the expense of spreading entries over more cache lines and at the
- cost of total memory consumed.
-
-* Growth rate upon hitting maximum load. Currently set to *2.
- Raising this to *4 results in half the number of resizes, less
- effort to resize, better sparseness for some (but not all dict sizes),
- and potentially doubles memory consumption depending on the size of
- the dictionary. Setting to *4 eliminates every other resize step.
-
-* Maximum sparseness (minimum dictionary load). What percentage
- of entries can be unused before the dictionary shrinks to
- free up memory and speed up iteration? (The current CPython
- code does not represent this parameter directly.)
-
-* Shrinkage rate upon exceeding maximum sparseness. The current
- CPython code never even checks sparseness when deleting a
- key. When a new key is added, it resizes based on the number
- of active keys, so that the addition may trigger shrinkage
- rather than growth.
+See comments for PyDict_MINSIZE_SPLIT, PyDict_MINSIZE_COMBINED,
+USABLE_FRACTION and GROWTH_RATE in dictobject.c
Tune-ups should be measured across a broad range of applications and
use cases. A change to any parameter will help in some situations and