# Environment Variables and Compiler Options

Triton-distributed-ascend environment variables and compiler options are inherited from **Triton Ascend** and **shmem (aclshmem)**. They can be used directly when developing Triton operators. For detailed lists, see the corresponding official documentation:

- **Triton Ascend**: Environment variables for debugging/logging, compilation control, runtime/scheduling, etc. See [Triton Ascend Environment Variables and Compiler Options Reference](https://triton-ascend.readthedocs.io/zh-cn/latest/environment_variable_and_compiler_options_reference.html).
- **shmem (aclshmem)**: Environment variables for initialization, logging, multi-instance, profiling, etc. See [shmem Logging and Debugging Documentation](https://shmem-doc.pages.dev/debug/log_debug).

## Environment Variables

Triton-distributed-ascend environment variables are divided into two categories:

- **Runtime environment variables**: Set during program execution.
- **Build-time environment variables**: Build configuration that takes effect when compiling and installing the Python package (`pip install -e ./python`), used by this project's build process; for detailed build steps and prerequisites (CANN, torch_npu, LLVM), see [README.md](../../../../README.md) and [build.md](../../../build.md).

### Environment Variable Usage Example

Environment variables need to be set before running the Python program, for example:

```
export SHMEM_UID_SESSION_ID=192.168.1.100:1234
python run_distributed_kernel.py
```

## Compiler Options

Compiler options are used to control the compilation strategy of individual Triton kernels. They can be passed via meta-parameters during kernel launch, `triton.Config`, or Autotune parameters.

### Compiler Option Usage Example

This project controls communication behavior within kernels through distributed primitives in `triton_dist.language` (`dl`) on the Ascend side, for example:

```python
import triton
import triton.language as tl
import triton_dist.language as dl
from triton.language.extra.cann.extension import sub_vec_id

@triton.jit
def notify_kernel(signal_ptr, rank):
    if sub_vec_id() == 0:
        # Send signal notification to rank 0: set 1
        dl.notify(
            signal_ptr, 0,
            signal=1, sig_op="set", comm_scope="intra_node",
        )

@triton.jit
def wait_kernel(signal_ptr, world_size):
    if sub_vec_id() == 0:
        # Wait for notifications from all other ranks (barrier scans in 64-byte stride)
        token = dl.wait(
            signal_ptr, world_size - 1,
            scope="gpu", _semantic="acquire", waitValue=1,
        )
        data_ptr = dl.consume_token(signal_ptr, token)
```

### Compiler Option Description

NPU compiler options for Triton distributed Ascend kernels (passed via `triton.Config` / launch meta-parameter) are defined by **Triton Ascend** and can be used directly when developing Triton operators. For detailed lists, see [Triton Ascend Environment Variables and Compiler Options Reference](https://triton-ascend.readthedocs.io/zh-cn/latest/environment_variable_and_compiler_options_reference.html).

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