Message377799
@vstinner @pablo @mark
On my local machine (without cpu isolation),
PR 22480 does not affect performance issues.
import pyperf
runner = pyperf.Runner()
runner.timeit(name="bench long divide",
stmt="""
for i in range(1, 256):
a = 10000 // i
""")
but I think that my benchmark does not cover the worst case.
I need to set up the CPU isolation environment but my resource is limited.
(I need a Linux machine with sufficient permission but not)
PR 22479 and PR 22480 has two sides of assumption.
PR 22479: PyNumber_FloorDivide is a heavy operation if the user thinks that this is an unnecessary operation it should be avoided.
(In this case divide by one)
PR 22480: PyNumber_FloorDivide should process handle unnecessary operations smartly.
In conclusion, I'd like to +1 on mark's decision.
- PR 22480: even though the divisor value is one, if the dividend is not qualified from PyLong_CheckExact it will not get an optimization path.
So it will not cover all the 'divide by one' case and it can cause performance issues.
- PR 22480: Always optimized if the user does not set a specific step value and this will be same effect on PR 22492. |
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Date |
User |
Action |
Args |
2020-10-02 06:55:18 | corona10 | set | recipients:
+ corona10, mark.dickinson, vstinner, serhiy.storchaka, ammar2, pablogsal |
2020-10-02 06:55:18 | corona10 | set | messageid: <1601621718.06.0.62278450135.issue41902@roundup.psfhosted.org> |
2020-10-02 06:55:18 | corona10 | link | issue41902 messages |
2020-10-02 06:55:17 | corona10 | create | |
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