mirror of
https://github.com/bevyengine/bevy
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d7c65e40ee
# Objective
Improve compile times.
## Solution
The `-Z threads=0` option has been introduced into nightly rust somewhat
recently, and was showcased in this [rust-lang
article](https://blog.rust-lang.org/2023/11/09/parallel-rustc.html).
This option improves multithreading in rust and speeds up compilation. I
added this option to `config_fast_builds.toml` so others can also use
this option to improve compile times.
`-Z threads=0` automatically uses the same amount of threads as the
amount of threads in your system (See [rustc source
code](6b4f1c5e78/compiler/rustc_session/src/options.rs (L617))).
### Benchmarks
> **Disclaimer:** This section was written before I knew of `-Z
threads=0`, so it uses `-Z threads=8` instead.
I compiled bevy with/without the `-Z threads=8` and saw about a 7%
improvement in compliation times on my Kubuntu system with a 13th Gen
Intel® Core™ i5-13400.
Also the compile times go down over time, probably because I had other
things running in the background.
#### Without `-Z threads=8`
- 42.33s
- 40.90s
- 38.27s
- 38.07s
- 37.17s
- 37.67s
- 36.63s
- 37.24s
**Average**: 38.535
#### With `-Z threads=8`
- 36.77s
- 39.50s
- 38.86s
- 35.61s
- 34.37s
- 34.32s
- 34.44s
- 33.74s
**Average**: 35.95125
40 lines
2 KiB
TOML
40 lines
2 KiB
TOML
# Add the contents of this file to `config.toml` to enable "fast build" configuration. Please read the notes below.
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# NOTE: For maximum performance, build using a nightly compiler
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# If you are using rust stable, remove the "-Zshare-generics=y" below.
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[target.x86_64-unknown-linux-gnu]
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linker = "clang"
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rustflags = [
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"-Clink-arg=-fuse-ld=lld", # Use LLD Linker
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"-Zshare-generics=y", # (Nightly) Make the current crate share its generic instantiations
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"-Zthreads=0", # (Nightly) Use improved multithreading with the recommended amount of threads.
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]
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# NOTE: you must install [Mach-O LLD Port](https://lld.llvm.org/MachO/index.html) on mac. you can easily do this by installing llvm which includes lld with the "brew" package manager:
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# `brew install llvm`
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[target.x86_64-apple-darwin]
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rustflags = [
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"-Clink-arg=-fuse-ld=/usr/local/opt/llvm/bin/ld64.lld", # Use LLD Linker
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"-Zshare-generics=y", # (Nightly) Make the current crate share its generic instantiations
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"-Zthreads=0", # (Nightly) Use improved multithreading with the recommended amount of threads.
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]
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[target.aarch64-apple-darwin]
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rustflags = [
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"-Clink-arg=-fuse-ld=/opt/homebrew/opt/llvm/bin/ld64.lld", # Use LLD Linker
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"-Zshare-generics=y", # (Nightly) Make the current crate share its generic instantiations
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"-Zthreads=0", # (Nightly) Use improved multithreading with the recommended amount of threads.
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]
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[target.x86_64-pc-windows-msvc]
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linker = "rust-lld.exe" # Use LLD Linker
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rustflags = [
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"-Zshare-generics=n",
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"-Zthreads=0", # (Nightly) Use improved multithreading with the recommended amount of threads.
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]
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# Optional: Uncommenting the following improves compile times, but reduces the amount of debug info to 'line number tables only'
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# In most cases the gains are negligible, but if you are on macos and have slow compile times you should see significant gains.
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#[profile.dev]
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#debug = 1
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