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Rust on Graviton

Rust is supported on Linux/arm64 systems as a tier1 platform along side x86.

Large-System Extensions (LSE)

Starting from Graviton2 processor in C6g[d], C6gn, M6g[d], R6g[d], T4g, X2gd, I4g, Im4gn, Is4gen, and G5g instances and all follow-on Graviton processors have support for the Armv8.2 instruction set. Armv8.2 specification includes the large-system extensions (LSE) introduced in Armv8.1. LSE provides low-cost atomic operations:

LSE improves system throughput for CPU-to-CPU communication, locks, and mutexes. The improvement can be up to an order of magnitude when using LSE instead of load/store exclusives. LSE can be enabled in Rust and we've seen cases on larger machines where performance is improved by over 3x by setting the RUSTFLAGS environment variable and rebuilding your project.

export RUSTFLAGS="-Ctarget-feature=+lse"
cargo build --release

If you're running only on Graviton2 or newer hardware you can also enable other instructions by setting the cpu target as well:

export RUSTFLAGS="-Ctarget-cpu=neoverse-n1"
cargo build --release

When Rust is configured to use LLVM 12 or newer, target feature +outline-atomics is available. Outline-atomics produces a binary containing two versions of the atomic operation following the hardware capabilities. When the code executes on a newer hardware such as Graviton2, the processor will execute LSE instructions; when the code executes on older hardware without LSE instructions, the processor will execute Armv8.0 atomics instructions.

Rust 1.57 (release on December 2, 2021) enables by default outline-atomics target feature when compiling for arm64-linux with LLVM 12 or newer. When using older Rust releases, outline-atomics target feature can be enabled with

export RUSTFLAGS="-Ctarget-feature=+outline-atomics"