You can also setup sccache both locally and in OBS - they help a ton.

With GNU ld and no sccache a Rust compiler build takes ~2 hours on my 8 core xeon

With lld and no sccache it takes ~1 hour.

With sccache warmed it takes 10 minutes.

It's worth looking into :)

> On 27 Apr 2023, at 15:59, Imobach Gonzalez Sosa <IGonzalezSosa@suse.com> wrote:
>
> Hi all,
>
> When working with a compiled language (like Rust, in this case), you must often rebuild the project to test your changes. On my system, after a small change, rebuilding Agama takes around 4 seconds[1]. TIL that most of the time is spent by the linker, and you can switch to a faster one if you wish. In my case, the build time was reduced to around 1.6 seconds.
>
> AFAIK, you have two options: lld[2] and mold[3], and both of them are available in openSUSE Tumbleweed.
>
> You need to install "clang" and "lld" or "mold" packages. Then, add the following lines to your ~/.cargo/config.toml file:
>
> [target.x86_64-unknown-linux-gnu]
> rustflags = ["-C", "linker=clang", "-C", "link-arg=-fuse-ld=lld"]
>
> Replace "lld" with "mold" if you prefer. And that's all 🙂
>
> PS: you can want to know how much time it takes to compile each crate, try "cargo build --timings" and check the generated report.
>
> Regards,
> Imo
>
> [1] Bear in mind that a complete rebuild takes around 35-40 seconds if the dependencies are already downloaded, but that's a different history.
> [2] https://lld.llvm.org/
> [3] https://github.com/rui314/mold


--
Sincerely,

William Brown

Senior Software Engineer,
Identity and Access Management
SUSE Labs, Australia