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docs: Add LLVM thread control documentation #130

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17 changes: 16 additions & 1 deletion pages/runtime/cli.mdx
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Expand Up @@ -45,6 +45,16 @@ wasmer run my_program.wasm --singlepass

> You can also use `--cranelift` or `--llvm` instead of `--singlepass`.

#### Run a Wasm file with LLVM thread control

When using the LLVM compiler, you can control how many threads are used during compilation:

```bash copy
wasmer run my_program.wasm --llvm --llvm-num-threads=4
```

> If the requested number of threads is 1, then rayon is not used during compilation, and modules are compiled on the calling thread.

### Run a WASI or WASIX Module

You can pass the arguments that will be given to the WASI program:
Expand All @@ -62,7 +72,7 @@ wasmer run my_wasi_program.wasm --env MYVAR=MYVALUE -- arg1 arg2 arg3

## Help

This is the help output from the Wasmer CLI for `wasmer run --help` (last updated 2025-01):
This is the help output from the Wasmer CLI for `wasmer run --help` (last updated 2025-04):

```
Run a WebAssembly file or Wasmer container
Expand Down Expand Up @@ -130,6 +140,11 @@ Options:
--llvm
Use LLVM compiler

--llvm-num-threads <NUM_THREADS>
Only available for the LLVM compiler. Sets the number of threads used to compile the input module(s).

If set to 1, compilation happens on the calling thread without using rayon.

--enable-verifier
Enable compiler internal verification.

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2 changes: 2 additions & 0 deletions pages/runtime/features.mdx
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Expand Up @@ -31,6 +31,7 @@ Each of this backends support different features, and have different support for
### Wasmer features
- **Caching**: compiled WebAssembly modules can be reused so subsequent runs of a Wasm file will have very little start up time;
- **Metering**: computation time and other resources can be monitored and limits set to control how the Wasm code runs. This is also known as "gas metering";
- **LLVM Thread Control**: control how many threads LLVM uses during compilation to optimize performance;

## Support of features by backend

Expand Down Expand Up @@ -58,6 +59,7 @@ Wasmer features:
| -------- | ---------- | --------- | ---- | -- | ----- | -------------- | ------- |
| Caching | ✅ | ✅ | ✅ | ❌ | ❌ | ❌ | ❌ |
| Metering | ✅ | ✅ | ✅ | ❌ | ❌ | ❌ | ❌ |
| Thread Control | ❌ | ❌ | ✅ | ❌ | ❌ | ❌ | ❌ |


## Backend support by Operating System
Expand Down