Hi, The Rust compiler and cargo have a very new feature called "pipelining". This feature increases the amount of parallelism available when building a multi-crate Rust project by overlapping the compilation of dependent crates.
For more details on how it works, and lots of measurements, see this thread: https://internals.rust-lang.org/t/evaluating-pipelined-rustc-compilation/10199 *Potential speedups* The speedups seen depend on various factors: - the structure of your project's crate graph; - the machine being used (machines with more cores are likely to see bigger speedups); - your build configuration (release/opt builds will speed up more than debug builds). On my 14-core Linux box some notable speedups of release/opt builds include: - webrender: 1.27x faster - cranelift-codegen: 1.20x faster - Firefox: 1.07x faster (and Firefox is of course mostly C++ code) On other projects we have seen as high as 1.84x improvement, while some projects see no speedup at all. At worst, it should make things only negligibly slower, because it's not doing significant additional work, just changing the order in which certain things happen. *How to use pipelining for Firefox* To try it in Firefox, do the following: - Do `rustup update nightly` to get a sufficiently recent compiler/cargo combination. - Do `rustup default nightly` to set the nightly compiler/cargo as your default. - Set the environment variable `CARGO_BUILD_PIPELINING=true`. - Build Firefox. If you want to evaluate its effectiveness before using it in earnest, you can use erahm's script, which does a bunch of timings: https://gist.github.com/EricRahm/d0bcedc0af5fcbd33dbedff497893cee The script builds Firefox 13 times, so it takes a while to run. It does a default opt build (`./mach -l build.log build`); you might want to change it to use your preferred mozconfig file. *How to use pipelining for other Rust projects* To try it in other Rust projects, do the following: - Do `rustup update nightly` to get a sufficiently recent compiler/cargo combination. - Do `CARGO_BUILD_PIPELINING=true cargo +nightly build` or something similar. *Caveats* Please note that pipelining is new and still experimental. It seems to work well but may have bugs. We hope to make it a stable feature soon. Alex Crichton did the implementation within Cargo and I did the implementation within rustc; please let us know about any problems. Nick _______________________________________________ dev-platform mailing list dev-platform@lists.mozilla.org https://lists.mozilla.org/listinfo/dev-platform
