[arch-general] Fedora Speeds Up Python 3.

[Chris Billington]

Ah, that's interesting.

I thought that would break my GIL profiling project that uses LD_PRELOAD
(shameless plug: https://github.com/chrisjbillington/gil_load), but since I
think I'm only overriding libc functions, it should be fine.

I'm sure there are other things it will break (I could have overridden
libpython functions instead - I wonder why I didn't, it seems simpler but
there was probably a reason), but if someone wants to use code that hacks
on the interpreter itself, having to install a custom python to do so is
not so unreasonable. Those speedups are nothing to scoff at.

-Chris




On Tue, Nov 26, 2019 at 5:07 AM Ralph Corderoy <ralph at inputplus.co.uk>
wrote:

> Hi,
>
> I thought this might be of interest.
> https://fedoraproject.org/wiki/Changes/PythonNoSemanticInterpositionSpeedup
>
> By building with -fno-semantic-interposition they remove the PLT that
> provides a level of indirection when calling a libpython function.
> libpython often calls itself and the PLT adds L1-cache pressure plus
> prevents inlining.  Gives gains of 25% on some workloads.
>
> --
> Cheers, Ralph.
>