[Python-Dev] cpython (2.7): Fix comment blocks. Adjust blocksize to a power-of-two for better divmod (original) (raw)
Benjamin Peterson benjamin at python.org
Sun Jun 23 20:38:26 CEST 2013
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I've backed this one out, too.
2013/6/22 Scott Dial <scott+python-dev at scottdial.com>:
On 6/22/2013 2:17 PM, Benjamin Peterson wrote:
Many people have raised concerns about this change, so I've now backed it out. I think that change also goes with this change: http://hg.python.org/cpython/rev/f1dc30a1be72 changeset 84248:f1dc30a1be72 2.7 Arrange structure to match the common access patterns. 1.1 --- a/Modules/collectionsmodule.c 1.2 +++ b/Modules/collectionsmodule.c 1.3 @@ -48,8 +48,8 @@ 1.4 1.5 typedef struct BLOCK { 1.6 struct BLOCK *leftlink; 1.7 + PyObject *data[BLOCKLEN]; 1.8 struct BLOCK *rightlink; 1.9 - PyObject *data[BLOCKLEN]; 1.10 } block; 1.11 1.12 #define MAXFREEBLOCKS 10 , which seems like a strange micro-optimization, at best. Based on that structure, it would seem that neither BLOCKLEN being 62 (previous value) nor 64 (the new value) make much sense. It would seem best that sizeof(block) == 64, so BLOCKLEN should be (64 - 2*sizeof(PyObject *)). Nevertheless, I am skeptical that any tuning of this structure provides any meaningful performance improvement. -- Scott Dial scott at scottdial.com
-- Regards, Benjamin
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