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authorRaymond Hettinger <python@rcn.com>2013-07-06 04:05:29 (GMT)
committerRaymond Hettinger <python@rcn.com>2013-07-06 04:05:29 (GMT)
commitde68e0cf0e6d94b087a3b7ae40e50843dff6d918 (patch)
tree9413154444e873a334d1885e0a78ef9181708fab /Modules
parent6597aa16b6044d8b5e31e176fed1865471499f08 (diff)
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Speed-up deque indexing by changing the deque block length to a power of two.
The division and modulo calculation in deque_item() can be compiled to fast bitwise operations when the BLOCKLEN is a power of two. Timing before: ~/cpython $ py -m timeit -r7 -s 'from collections import deque' -s 'd=deque(range(10))' 'd[5]' 10000000 loops, best of 7: 0.0627 usec per loop Timing after: ~/cpython $ py -m timeit -r7 -s 'from collections import deque' -s 'd=deque(range(10))' 'd[5]' 10000000 loops, best of 7: 0.0581 usec per loop
Diffstat (limited to 'Modules')
-rw-r--r--Modules/_collectionsmodule.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
index b922475..781949d 100644
--- a/Modules/_collectionsmodule.c
+++ b/Modules/_collectionsmodule.c
@@ -14,7 +14,7 @@
* division/modulo computations during indexing.
*/
-#define BLOCKLEN 62
+#define BLOCKLEN 64
#define CENTER ((BLOCKLEN - 1) / 2)
/* A `dequeobject` is composed of a doubly-linked list of `block` nodes.