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torchada

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Run your CUDA code on Moore Threads GPUs — zero code changes required

torchada is an adapter that makes torch_musa (Moore Threads GPU support for PyTorch) compatible with standard PyTorch CUDA APIs. Import it once, and your existing torch.cuda.* code works on MUSA hardware.

Why torchada?

Many PyTorch projects are written for NVIDIA GPUs using torch.cuda.* APIs. To run these on Moore Threads GPUs, you would normally need to change every cuda reference to musa. torchada eliminates this by automatically translating CUDA API calls to MUSA equivalents at runtime.

Prerequisites

• torch_musa: You must have torch_musa installed (this provides MUSA support for PyTorch)
• Moore Threads GPU: A Moore Threads GPU with proper driver installed

Installation

pip install torchada

# Or install from source
git clone https://github.com/MooreThreads/torchada.git
cd torchada
pip install -e .

Quick Start

import torchada  # ← Add this one line at the top
import torch

# Your existing CUDA code works unchanged:
x = torch.randn(10, 10).cuda()
print(torch.cuda.device_count())
torch.cuda.synchronize()

That's it! All torch.cuda.* APIs are automatically redirected to torch.musa.*.

What Works

Feature	Example
Device operations	tensor.cuda(), model.cuda(), torch.device("cuda")
Memory management	torch.cuda.memory_allocated(), empty_cache()
Synchronization	torch.cuda.synchronize(), Stream, Event
Mixed precision	torch.cuda.amp.autocast(), GradScaler()
CUDA Graphs	torch.cuda.CUDAGraph, torch.cuda.graph()
CUDA Runtime	torch.cuda.cudart() → uses MUSA runtime
Profiler	ProfilerActivity.CUDA → uses PrivateUse1
Custom Ops	Library.impl(..., "CUDA") → uses PrivateUse1
Distributed	dist.init_process_group(backend='nccl') → uses MCCL
torch.compile	torch.compile(model) with all backends
C++ Extensions	CUDAExtension, BuildExtension, load()
FlexAttention	torch.nn.attention.flex_attention works on MUSA
ctypes Libraries	ctypes.CDLL with CUDA function names → MUSA equivalents
Unified Accelerator API	torch.accelerator.empty_cache(), memory_stats(), Stream, Event, ...

Examples

Mixed Precision Training

import torchada
import torch

model = MyModel().cuda()
scaler = torch.cuda.amp.GradScaler()

with torch.cuda.amp.autocast():
    output = model(data.cuda())
    loss = criterion(output, target.cuda())

scaler.scale(loss).backward()
scaler.step(optimizer)
scaler.update()

Distributed Training

import torchada
import torch.distributed as dist

# 'nccl' is automatically mapped to 'mccl' on MUSA
dist.init_process_group(backend='nccl')

CUDA Graphs

import torchada
import torch

g = torch.cuda.CUDAGraph()
with torch.cuda.graph(cuda_graph=g):  # cuda_graph= keyword works on MUSA
    y = model(x)

torch.compile

import torchada
import torch

compiled_model = torch.compile(model.cuda(), backend='inductor')

Building C++ Extensions

import torchada  # Must import before torch.utils.cpp_extension
from torch.utils.cpp_extension import CUDAExtension, BuildExtension

# Standard CUDAExtension works — torchada handles CUDA→MUSA translation
ext = CUDAExtension("my_ext", sources=["kernel.cu"])

Custom Ops

import torchada
import torch

my_lib = torch.library.Library("my_lib", "DEF")
my_lib.define("my_op(Tensor x) -> Tensor")
my_lib.impl("my_op", my_func, "CUDA")  # Works on MUSA!

Profiler

import torchada
import torch

# ProfilerActivity.CUDA works on MUSA
with torch.profiler.profile(
    activities=[torch.profiler.ProfilerActivity.CPU, torch.profiler.ProfilerActivity.CUDA]
) as prof:
    model(x)

ctypes Library Loading

import torchada
import ctypes

# Load MUSA runtime library with CUDA function names
lib = ctypes.CDLL("libmusart.so")
func = lib.cudaMalloc  # Automatically translates to musaMalloc

# Works with MCCL too
nccl_lib = ctypes.CDLL("libmccl.so")
func = nccl_lib.ncclAllReduce  # Automatically translates to mcclAllReduce

Unified Accelerator API (torch.accelerator)

torch.accelerator is PyTorch's unified backend-agnostic entry point. Its API surface is expanding across PyTorch releases, so APIs such as empty_cache(), memory_stats(), Stream, and Event are not yet present in torch 2.7 even though they exist on torch.musa. torchada wraps torch.accelerator so code written against the newer unified API works today:

import torchada
import torch

# APIs that exist in torch 2.7 keep their official implementation
torch.accelerator.is_available()
torch.accelerator.device_count()

# APIs missing from torch 2.7 transparently fall back to torch.musa
torch.accelerator.empty_cache()
torch.accelerator.memory_allocated()
torch.accelerator.memory_stats()
torch.accelerator.manual_seed(42)
s = torch.accelerator.Stream()
e = torch.accelerator.Event()

# Patched to delegate to torch.musa.synchronize() (the default MUSA
# implementation does not support synchronizing all streams on a device)
torch.accelerator.synchronize()

# Context managers for forward compatibility with PyTorch 2.9+
with torch.accelerator.device_index(0):
    ...
with torch.accelerator.stream(torch.musa.Stream()):
    ...

Forward compatibility: The wrapper always prefers the real torch.accelerator implementation and only falls back to torch.musa when an attribute is missing, so upgrading to a future PyTorch release that ships official implementations requires no changes on your side — you will automatically get the upstream version.

Platform Detection

import torchada
from torchada import detect_platform, Platform

platform = detect_platform()
if platform == Platform.MUSA:
    print("Running on Moore Threads GPU")
elif platform == Platform.CUDA:
    print("Running on NVIDIA GPU")

# Or use torch.version-based detection
def is_musa():
    import torch
    return hasattr(torch.version, 'musa') and torch.version.musa is not None

Performance

torchada uses aggressive caching to minimize runtime overhead. All frequently-called operations complete in under 200 nanoseconds:

Operation	Overhead
torch.cuda.device_count()	~140ns
torch.cuda.Stream (attribute access)	~130ns
torch.cuda.Event (attribute access)	~130ns
_translate_device('cuda')	~140ns
torch.backends.cuda.is_built()	~155ns

For comparison, a typical GPU kernel launch takes 5,000-20,000ns. The patching overhead is negligible for real-world applications.

Operations with inherent costs (runtime calls, object creation) take 300-600ns but cannot be optimized further without changing behavior.

Known Limitation

Device type string comparisons fail on MUSA:

device = torch.device("cuda:0")  # On MUSA, this becomes musa:0
device.type == "cuda"  # Returns False!

Solution: Use torchada.is_gpu_device():

import torchada

if torchada.is_gpu_device(device):  # Works on both CUDA and MUSA
    ...
# Or: device.type in ("cuda", "musa")

API Reference

Function	Description
detect_platform()	Returns Platform.CUDA, Platform.MUSA, or Platform.CPU
is_musa_platform()	Returns True if running on MUSA
is_cuda_platform()	Returns True if running on CUDA
is_gpu_device(device)	Returns True if device is CUDA or MUSA
CUDA_HOME	Path to CUDA/MUSA installation
cuda_to_musa_name(name)	Convert cudaXxx → musaXxx
nccl_to_mccl_name(name)	Convert ncclXxx → mcclXxx
cublas_to_mublas_name(name)	Convert cublasXxx → mublasXxx
curand_to_murand_name(name)	Convert curandXxx → murandXxx

Note: torch.cuda.is_available() is intentionally NOT redirected — it returns False on MUSA. This allows proper platform detection. For GPU availability checks, see the has_gpu() pattern in examples/migrate_existing_project.md.

Note: The name conversion utilities are exported for manual use, but ctypes.CDLL is automatically patched to translate function names when loading MUSA libraries.

C++ Extension Symbol Mapping

When building C++ extensions, torchada automatically translates CUDA symbols to MUSA:

CUDA	MUSA
cudaMalloc	musaMalloc
cudaStream_t	musaStream_t
cublasHandle_t	mublasHandle_t
at::cuda	at::musa
c10::cuda	c10::musa
#include <cuda/*>	#include <musa/*>

See src/torchada/_mapping.py for the complete mapping table (380+ mappings).

Integrating torchada into Your Project

Step 1: Add Dependency

# pyproject.toml or requirements.txt
torchada>=0.1.51

Step 2: Conditional Import

# At your application entry point
def is_musa():
    import torch
    return hasattr(torch.version, "musa") and torch.version.musa is not None

if is_musa():
    import torchada  # noqa: F401

# Rest of your code uses torch.cuda.* as normal

Step 3: Extend Feature Flags (if applicable)

# Include MUSA in GPU capability checks
if is_nvidia() or is_musa():
    ENABLE_FLASH_ATTENTION = True

Step 4: Fix Device Type Checks (if applicable)

# Instead of: device.type == "cuda"
# Use: device.type in ("cuda", "musa")
# Or: torchada.is_gpu_device(device)

Projects Using torchada

Project	Category	Status	Tracking
Xinference	Model Serving	✅ Merged	—
LightLLM	Model Serving	✅ Merged	—
LightX2V	Image/Video Generation	✅ Merged	—
Chitu	Model Serving	✅ Merged	—
vLLM-MUSA	Model Serving	✅ Merged	—
SGLang	Model Serving	🚧 In Progress	SGLang#16565
ComfyUI	Image/Video Generation	🚧 In Progress	ComfyUI#11618
vLLM-Omni	Model Serving (Omni)	🚧 In Progress	vLLM-Omni#2347

License

MIT License