Andy Wingo <wi...@pobox.com> skribis: > On Fri 24 Jun 2016 10:28, l...@gnu.org (Ludovic Courtès) writes: > >> Hello! >> >> Andy Wingo <wi...@pobox.com> skribis: >> >>> On Thu 23 Jun 2016 15:06, l...@gnu.org (Ludovic Courtès) writes: >>> >>>> ‘canonicalize_file_name’ is costly: roughly one syscall per file name >>>> component. >>>> >>>> IIUC, ‘canonicalize_file_name’ is now called once for each ‘%load-path’ >>>> entry and file name that we canonicalize. Is this correct? >>> >>> That's correct, but only for relative canonicalization, which is in >>> practive only when loading Scheme files from source. Seems out of the >>> hot path; what do you think? >> >> I think it’s likely to have a noticeable impact on startup time for >> projects with a large number of modules like Guix. > > Aren't they usually compiled? Loading compiled files will not > go through this path AFAIU.
Good point, I had overlooked that. >> For instance, commands like ‘guix package -A’ or ‘guix build foo’ load >> all the modules. The impact will be smaller on a laptop with an SSD >> than on an NFS mount, where it’s likely going to be terrrible (this >> could be tested using the ‘delay’ device mapper.) > > Oh I'm with you that we need to be careful here. I am under the > impression though that there's no additional impact here because this is > just something that happens at compile-time. Or if you load a source > file, but in that case you're evaluating and expecting a perf loss is > not the end of the world. Indeed, this makes sense to me now; sorry for the confusion! Ludo’.
