New submission from Sergey Fedoseev <fedoseev.ser...@gmail.com>:
Currently list concatenation, slicing and repeating operations are using PyList_New() which allocates memory for the items by calloc(). malloc() could be used instead, since the allocated memory is overwritten by mentioned operations. I made benchmarks with this script: NAME=list-malloc-master.json python -m perf timeit --name slice0 -s "l = [None]*1000000" "l[:0]" --duplicate=2048 --append $NAME python -m perf timeit --name slice1 -s "l = [None]*1000000" "l[:1]" --duplicate=1024 --append $NAME python -m perf timeit --name slice2 -s "l = [None]*1000000" "l[:2]" --duplicate=1024 --append $NAME python -m perf timeit --name slice3 -s "l = [None]*1000000" "l[:3]" --duplicate=1024 --append $NAME python -m perf timeit --name slice1000000 -s "l = [None]*1000000" "l[:1000000]" --append $NAME python -m perf timeit --name cat0 -s "l = [None]*0" "l + l" --duplicate=1024 --append $NAME python -m perf timeit --name cat1 -s "l = [None]*1" "l * 1" --duplicate=1024 --append $NAME python -m perf timeit --name cat2 -s "l = [None]*2" "l * 1" --duplicate=1024 --append $NAME python -m perf timeit --name cat3 -s "l = [None]*3" "l * 1" --duplicate=1024 --append $NAME python -m perf timeit --name cat1000000 -s "l = [None]*1000000" "l * 1" --append $NAME python -m perf timeit --name 1x0 -s "l = [None]" "l * 0" --duplicate=1024 --append $NAME python -m perf timeit --name 1x1 -s "l = [None]" "l * 1" --duplicate=1024 --append $NAME python -m perf timeit --name 1x2 -s "l = [None]" "l * 2" --duplicate=1024 --append $NAME python -m perf timeit --name 1x3 -s "l = [None]" "l * 3" --duplicate=1024 --append $NAME python -m perf timeit --name 1x1000000 -s "l = [None]" "l * 1000000" --append $NAME Here's comparison table: +--------------+--------------------+------------------------------+ | Benchmark | list-malloc-master | list-malloc | +==============+====================+==============================+ | slice1 | 84.5 ns | 59.6 ns: 1.42x faster (-30%) | +--------------+--------------------+------------------------------+ | slice2 | 71.6 ns | 61.8 ns: 1.16x faster (-14%) | +--------------+--------------------+------------------------------+ | slice3 | 74.4 ns | 63.6 ns: 1.17x faster (-15%) | +--------------+--------------------+------------------------------+ | slice1000000 | 4.39 ms | 4.08 ms: 1.08x faster (-7%) | +--------------+--------------------+------------------------------+ | cat0 | 23.9 ns | 24.9 ns: 1.04x slower (+4%) | +--------------+--------------------+------------------------------+ | cat1 | 73.2 ns | 51.9 ns: 1.41x faster (-29%) | +--------------+--------------------+------------------------------+ | cat2 | 61.6 ns | 53.1 ns: 1.16x faster (-14%) | +--------------+--------------------+------------------------------+ | cat3 | 63.0 ns | 54.3 ns: 1.16x faster (-14%) | +--------------+--------------------+------------------------------+ | cat1000000 | 4.38 ms | 4.08 ms: 1.07x faster (-7%) | +--------------+--------------------+------------------------------+ | 1x0 | 27.1 ns | 27.7 ns: 1.02x slower (+2%) | +--------------+--------------------+------------------------------+ | 1x1 | 72.9 ns | 51.9 ns: 1.41x faster (-29%) | +--------------+--------------------+------------------------------+ | 1x2 | 60.9 ns | 52.9 ns: 1.15x faster (-13%) | +--------------+--------------------+------------------------------+ | 1x3 | 62.5 ns | 54.8 ns: 1.14x faster (-12%) | +--------------+--------------------+------------------------------+ | 1x1000000 | 2.67 ms | 2.34 ms: 1.14x faster (-12%) | +--------------+--------------------+------------------------------+ Not significant (1): slice0 ---------- components: Interpreter Core messages: 321905 nosy: sir-sigurd priority: normal severity: normal status: open title: use malloc() for better performance of some list operations type: performance _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue34151> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
