mold does not accelerate the compile process compare to normal config about mold

[rui314]

If that's the case it is what it is. If linking is not the bottleneck of your build process, mold can't make it faster. Maybe your binary is relatively small?

[Mon-ius]

I am aware if the process I have done for configure the mold is right, the linking part normally spent over 1min to process on Intel(R) Xeon(R) Platinum 8360Y CPU @ 2.40GHz in this case.

[rui314]

What is the overall wallclock time to build the entire source tree? What if you change a single file and rebuild it?

[Mon-ius]

If change single file and rebuild it when RUSTFLAGS="-C linker=clang -C link-arg=-fuse-ld=mold" cargo build --release, it spent 34.20s/1m 11s, 34.20s is for change a single file and rebuild it, 1m 11s is overall spend.

However, when pure perform cargo build --release without any FLAGs, it spent the similar, 34.66s/1m 45s.

When perform RUSTFLAGS="-C linker=clang -C link-arg=-fuse-ld=mold -Z threads=32" cargo +nightly build --release, 34.63s/1m 42s

Each build test after cargo clean.

[rui314]

You don't want to run cargo clean after making a change to a file. Just change a single file and rebuild it, which is a typical scenario, and measure how much time does each build takes.

[Mon-ius]

As mentioned, 34.20s, 34.66s and 34.63s are the time spent by change a single file and rebuild it. So, wired is, the three build process make no different

[rui314]

What if you do not change anything but just delete the generated executable and rebuild it?

[Mon-ius]

@rui314 as you request,

• 0.14s for standard cargo build --release
• 0.14s for RUSTFLAGS="-Z threads=32" cargo +nightly build --release
• 0.11s for RUSTFLAGS="-C linker=clang -C link-arg=-fuse-ld=mold" cargo build --release
• 0.11s for RUSTFLAGS="-C linker=clang -C link-arg=-fuse-ld=mold -Z threads=32" cargo +nightly build --release

[rui314]

I'm not familiar with the rust build system, but aren't that the time the linkers take to link your program? If that's the case, the faster linker can't make any difference.

[Mon-ius]

it takes about 0.03s faster in this case. One more question, does mold compatible with https://github.com/rust-lang/rustc_codegen_cranelift

[rui314]

Yes