openpilot_comma/tinygrad_repo/docs/runtime.md

Runtimes

tinygrad supports various runtimes, enabling your code to scale across a wide range of devices. The default runtime can be automatically selected based on the available hardware, or you can force a specific runtime to be default using environment variables (e.g., CPU=1).

Runtime	Description	Compiler Options	Requirements
NV	Provides acceleration for NVIDIA GPUs	nvrtc (default) PTX (NV_PTX=1)	Ampere/Ada/Blackwell series GPUs. You can select an interface via NV_IFACE=(NVK|PCI). See NV interfaces for details.
AMD	Provides acceleration for AMD GPUs	LLVM (AMD_LLVM=1) HIP/COMGR (AMD_HIP=1)	RDNA2 or newer GPUs. You can select an interface via AMD_IFACE=(KFD|PCI|USB). See AMD interfaces for details.
QCOM	Provides acceleration for QCOM GPUs	-	6xx series GPUs
METAL	Utilizes Metal for acceleration on Apple devices	-	M1+ Macs; Metal 3.0+ for bfloat support
CUDA	Utilizes CUDA for acceleration on NVIDIA GPUs	nvrtc (default) PTX (CUDA_PTX=1)	NVIDIA GPU with CUDA support
CL	Accelerates computations using OpenCL on GPUs	-	OpenCL 2.0 compatible device
CPU	Runs on CPU using the clang or llvm compiler	Clang JIT (default) LLVM IR (CPU_LLVM=1)	clang compiler in system PATH
WEBGPU	Runs on GPU using the Dawn WebGPU engine (used in Google Chrome)	-	Dawn library installed and discoverable. Binaries: pydawn v0.3.0

Interoperability

tinygrad provides interoperability with OpenCL and PyTorch, allowing efficient tensor data sharing between frameworks through the Tensor.from_blob API. This enables zero-copy operations by working directly with external memory pointers.

Important: When using external memory pointers with tinygrad tensors, you must ensure these pointers remain valid throughout the entire lifetime of the tinygrad tensor to prevent memory corruption.

CUDA/METAL PyTorch Interoperability

You can seamlessly work with CUDA/MPS tensors between PyTorch and tinygrad without data copying:

from tinygrad.dtype import _from_torch_dtype
tensor1 = torch.tensor([1.0, 2.0, 3.0], device=torch.device("cuda"))
tiny_tensor1 = Tensor.from_blob(tensor1.data_ptr(), tensor1.shape, dtype=_from_torch_dtype(tensor1.dtype), device='CUDA')

# Before tinygrad calculations, mps needs to be synchronized to make sure data is valid.
if data.device.type == "mps": torch.mps.synchronize()
else: torch.cuda.synchronize()

x = (tiny_tensor1 + 1).realize()

QCOM OpenCL Interoperability

tinygrad supports OpenCL interoperability on QCOM backend.

Buffer interop allows direct access to OpenCL memory buffers:

# create raw opencl buffer.
cl_buf = cl.clCreateBuffer(cl_context, cl.CL_MEM_READ_WRITE, 0x100, None, status := ctypes.c_int32())

# extract pointers
cl_buf_desc_ptr = to_mv(ctypes.addressof(cl_buf), 8).cast('Q')[0]
rawbuf_ptr = to_mv(cl_buf_desc_ptr, 0x100).cast('Q')[20] # offset 0xA0 is a raw gpu pointer.

# create tiny tensor
tiny = Tensor.from_blob(rawbuf_ptr, (8, 8), dtype=dtypes.int, device='QCOM')

And the same for the images:

# create cl image.
cl_img = cl.clCreateImage2D(cl_context, cl.CL_MEM_READ_WRITE, cl.cl_image_format(cl.CL_RGBA, cl.CL_FLOAT), w, h, 0, None, status := ctypes.c_int32())

# extract pointers
cl_buf_desc_ptr = to_mv(ctypes.addressof(cl_img), 8).cast('Q')[0]
rawbuf_ptr = to_mv(cl_buf_desc_ptr, 0x100).cast('Q')[20] # offset 0xA0 is a raw gpu pointer.

# create tiny tensor
tiny = Tensor.from_blob(rawbuf_ptr, (h*w*4,), dtype=dtypes.imagef((h,w)), device='QCOM')

AMD Interfaces

AMD backend supports several interfaces for communicating with devices:

• KFD: uses the amdgpu driver
• PCI: uses the AM driver
• USB: USB3 interafce for asm24xx chips.

You can force an interface by setting AMD_IFACE to one of these values. In the case of AMD_IFACE=PCI, this may unbind your GPU from the amdgpu driver.

NV Interfaces

NV backend supports several interfaces for communicating with devices:

• NVK: uses the nvidia driver
• PCI: uses the NV driver