metal PyTorch interop (#9229)

* add from_blob support to mps cuda

* objc_id

* metal pytorch interop

* fix comments

---------

Co-authored-by: George Hotz <geohot@gmail.com>

docs/runtime.md

@@ -20,13 +20,19 @@ tinygrad provides interoperability with OpenCL and PyTorch, allowing efficient t
 
 **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` PyTorch Interoperability
+### `CUDA`/`METAL` PyTorch Interoperability
 
-You can seamlessly work with CUDA tensors between PyTorch and tinygrad without data copying:
+You can seamlessly work with CUDA/MPS tensors between PyTorch and tinygrad without data copying:
 ```python
 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

examples/torch_cuda_kernel.py

@@ -3,32 +3,34 @@
 # not a stable API, but works
 
 import torch, functools
-try:
-  import tinygrad
-except ImportError:
-  import pip
-  pip.main(['install', 'tinygrad'])
-
 from tinygrad import Tensor, TinyJit
 from tinygrad.engine.realize import CompiledRunner
-from tinygrad.helpers import get_single_element, Context
+from tinygrad.helpers import get_single_element, Context, OSX
 from tinygrad.dtype import _from_torch_dtype
 
 @TinyJit
 def f(tg_out, tg_data): return tg_out.assign(tg_data[:, :, 0] * 0.2989 + tg_data[:, :, 1] * 0.5870 + tg_data[:, :, 2] * 0.1140).realize()
 
-def custom_kernel(data: torch.Tensor) -> torch.Tensor:
+def custom_kernel(data: torch.Tensor, device="CUDA") -> torch.Tensor:
   assert data.dtype == torch.float32
-  tg_data = Tensor.from_blob(data.data_ptr(), data.shape, dtype=_from_torch_dtype(data.dtype), device='CUDA')
+  tg_data = Tensor.from_blob(data.data_ptr(), data.shape, dtype=_from_torch_dtype(data.dtype), device=device)
 
   out = torch.empty((data.shape[0], data.shape[1]), dtype=data.dtype, device=data.device)
-  tg_out = Tensor.from_blob(out.data_ptr(), out.shape, dtype=_from_torch_dtype(out.dtype), device='CUDA')
+  tg_out = Tensor.from_blob(out.data_ptr(), out.shape, dtype=_from_torch_dtype(out.dtype), device=device)
+
+  # Need to sync torch to make sure the data is valid.
+  if data.device.type == "mps": torch.mps.synchronize()
+  else: torch.cuda.synchronize()
 
   with Context(BEAM=2): f(tg_out, tg_data)
+
+  # Since realize() is called in f(), at this point tinygrad has finished the computation and the data is valid.
   return out
 
 if __name__ == "__main__":
   for i in range(3):
-    out = custom_kernel(inp:=torch.rand(16, 16, 3, device=torch.device("cuda")))
-    torch.cuda.synchronize()
+    if OSX:
+      out = custom_kernel(inp:=torch.rand(16, 16, 3, device=torch.device("mps")), device="METAL")
+    else:
+      out = custom_kernel(inp:=torch.rand(16, 16, 3, device=torch.device("cuda")), device="CUDA")
     assert torch.allclose(out, inp[:, :, 0] * 0.2989 + inp[:, :, 1] * 0.5870 + inp[:, :, 2] * 0.1140)

tinygrad/runtime/ops_metal.py

@@ -192,6 +192,8 @@ class MetalAllocator(LRUAllocator):
     self.dev:MetalDevice = dev
     super().__init__()
   def _alloc(self, size:int, options) -> MetalBuffer:
+    if options.external_ptr: return MetalBuffer(objc_id(options.external_ptr), size)
+
     # Buffer is explicitly released in _free() rather than garbage collected via reference count
     ret = msg("newBufferWithLength:options:", objc_id)(self.dev.sysdevice, ctypes.c_ulong(size), MTLResourceOptions.MTLResourceStorageModeShared)
     if ret.value is None: raise MemoryError(f"Metal OOM while allocating {size=}")