On 15.09.16 11:02, INADA Naoki wrote:
Are two Pythons built with same options?
Both are built from clean checkout with default options (hg update -C
3.x; ./configure; make -s). The only difference is -std=c99 and
additional warnings in 3.6:
Python 3.5:
gcc -pthread -c -Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv
-O3 -Wall -Wstrict-prototypes -Werror=declaration-after-statement
-I. -I./Include -DPy_BUILD_CORE -o Objects/dictobject.o
Objects/dictobject.c
Python 3.6:
gcc -pthread -c -Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv
-O3 -Wall -Wstrict-prototypes -std=c99 -Wextra -Wno-unused-result
-Wno-unused-parameter -Wno-missing-field-initializers -I. -I./Include
-DPy_BUILD_CORE -o Objects/dictobject.o Objects/dictobject.c
Usually I run a microbenchmark 3-5 times and choose the median. Results
was stable enough (the variation is about 1%), unlikely the perf tool
will give significantly different result.
I repeated measurements on different computer, the difference is the same:
Python 3.5: 10 loops, best of 3: 33.5 msec per loop
Python 3.6: 10 loops, best of 3: 37.5 msec per loop
These results look surprisingly and inexplicably to me. I expected that
even if there is some performance regression in the lookup or modifying
operation, the iteration should not be slower.
CPUs on both computers work in 32-bit mode. Maybe this affects.
For string keys Python 3.6 is 4 times faster!
$ ./python -m timeit -s "d = dict.fromkeys(map(str, range(10**6)))" --
"list(d)"
On one computer:
Python 3.5: 10 loops, best of 3: 384 msec per loop
Python 3.6: 10 loops, best of 3: 94.6 msec per loop
On other computer:
Python 3.5: 10 loops, best of 3: 179 msec per loop
Python 3.6: 10 loops, best of 3: 46 msec per loop
_______________________________________________
Python-Dev mailing list
Python-Dev@python.org
https://mail.python.org/mailman/listinfo/python-dev
Unsubscribe:
https://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
