Oh I remember why I didn't override libpython functions with LD_PRELOAD. Python is statically linked to libpython in Ubuntu, which I was using at the time, so it didn't work. Fedora decided not to go that far, but yeah, Ubuntu has already taken that plunge. If LD_PRELOADing libpython doesn't work in Ubuntu, then there probably aren't many projects using it. On Tue, Nov 26, 2019 at 9:31 AM Chris Billington <chrisjbillington@xxxxxxxxx> wrote: > 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@xxxxxxxxxxxxxxx> > 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. >> >
