Message404317
Given this feedback:
https://github.com/python/cpython/pull/14474/files#r725488766
it is perhaps not so safe to assume that only the lower 48 bits of virtual addresses are significant. I had the idea that Go made similar assumptions but now I'm not sure it does. There is also a comment in this article about 5-level page tables in Linux:
https://lwn.net/Articles/717293/
https://lwn.net/Articles/717300/
I.e. that Linux does not allocate virtual address space above 47-bit by default.
Setting ADDRESS_BITS to 64 is safer and the performance impact seems small. The virtual memory size of a small Python process goes up a little. Resident set size doesn't significantly change. I think the pyperformance changes are just noise. The pyperformance attached file shows the 3.10 branch with ADDRESS_BITS set to 48 and to 64. |
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2021-10-19 16:48:44 | nascheme | set | recipients:
+ nascheme, methane |
2021-10-19 16:48:44 | nascheme | set | messageid: <1634662124.91.0.148058700143.issue45526@roundup.psfhosted.org> |
2021-10-19 16:48:44 | nascheme | link | issue45526 messages |
2021-10-19 16:48:44 | nascheme | create | |
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