set `JULIA_CPU_TARGET` to avoid compilation overhead

Question

set `JULIA_CPU_TARGET` to avoid compilation overhead

BioTurboNick opened this issue a year ago · comments

If someone wishes to use this container and pre-load packages for their own, they may find that every time they run the container remotely, Julia spends time compiling before anything can happen.

This is because on an individual system Julia will just compile code for that specific architecture. A remote system with a slightly different architecture will trigger re-compilation.

To make the compilation that happens during container building stick, the JULIA_CPU_TARGET environment variable needs to be set to the generic string that is used to build Julia in the first place:

ENV JULIA_CPU_TARGET generic;sandybridge,-xsaveopt,clone_all;haswell,-rdrnd,base(1)

See: https://docs.julialang.org/en/v1/devdocs/sysimg/#Specifying-multiple-system-image-targets

Mosè Giordano · Answer 1 · Fri May 12 2023 02:32:58 GMT+0800 (China Standard Time)

For reference, these are the targets settings for all the architectures: https://github.com/JuliaCI/julia-buildkite/blob/9c9f7d324c94130f36e52a386274aa250baef495/utilities/build_envs.sh#L20-L73

Tianon Gravi · Answer 2 · Fri May 12 2023 03:44:10 GMT+0800 (China Standard Time)

Oh, that's really interesting, thanks for the useful links!

My biggest question here is whether this is something we should be setting to something sanely generic by default, or whether this is something we should instead document for users to choose for themselves?

(I imagine the default behavior wasn't chosen arbitrarily, but probably also wasn't chosen for the use case of sharing the built results like Docker images enable/encourage. 😅)