Is it only me, or are the instructions missing the measurements for non-fresh non-incremental builds? The number 3. contains all the work for building the crate itself and all the dependencies, and then there’s the incremental stuff, but the non-fresh incremental builds can’t hardly be compared to the full build time, only to the single-crate (dependencies already built) time. I added touching and trivial changes in non-incremental mode as numbers 3.1 and 3.2 to account for this.
I tried compiling the rls crate which I have been playing with lately.
Non-incremental builds
3. rm -rf target && CARGO_INCREMENTAL=0 time cargo +nightly build --release
358.96 real 1126.37 user 40.12 sys
3.1. touch src/main.rs && CARGO_INCREMENTAL=0 time cargo +nightly build --release
81.81 real 80.89 user 0.85 sys
3.2. adding a println! statement and doing CARGO_INCREMENTAL=0 time cargo +nightly build --release
89.60 real 86.64 user 1.57 sys
Incremental builds
4. rm -rf target && CARGO_INCREMENTAL=1 time cargo +nightly build --release
194.50 real 1158.00 user 43.83 sys
5. touch src/main.rs && CARGO_INCREMENTAL=1 time cargo +nightly build --release
8.11 real 7.27 user 0.92 sys
6. adding a println! statement and doing CARGO_INCREMENTAL=1 time cargo +nightly build --release
8.01 real 7.32 user 0.86 sys
I’d like to get a confirmation from @aturon, is missing touch and trivial changes with non-incrementals in the instructions just an omission or is there some reason not to do comparisons/not to be interested with that?
Edit: I almost forgot to say: the incremental builds seem to provide HUGE wins. So big kudos to the implementors! I already said this in twitter, but… wow, I feel this is like unlocking a superpower on Rust!