Reduce CPU usage for cargo run

Question

During cargo run, rustc by default takes up all CPU resources. Is it possible to limit CPU usage? For example, cpulimit -l 40 works for cargo, but rustc processes still use 100% of the CPU.

1. Fedora release 40 (Forty): 6.9.7-200.fc40.x86_64 #1 SMP PREEMPT_DYNAMIC
2. rustc 1.79.0 (129f3b996 2024-06-10)
3. cargo 1.79.0 (ffa9cf99a 2024-06-03)
4. stable-x86_64-unknown-linux-gnu unchanged -rustc 1.79.0 (129f3b996 2024-06-10)

UPD: cargo build -j x or CARGO_BUILD_JOBS=x this helped.

Answer 1

question was reducing cpu usage during cargo run. -j 1 does only work for cargo build.

so the combined answer of all those helpful comments would be something like this:

CARGO_BUILD_JOBS=1 systemd-run --scope --user --property CPUQuota=50% cargo run

sidenote: my problem was memory usage slowing the process down. to reduce the memory use: CARGO_BUILD_JOBS=1 systemd-run --scope --user --property CPUQuota=50% --property MemoryMax=500M --property MemorySwapMax=0