Add CachedModelWithPartialLoad to manage partially-loaded models using the new autocast modules.

invokeai/backend/model_manager/load/model_cache/cached_model/cached_model_with_partial_load.py

@@ -0,0 +1,183 @@
+import torch
+
+from invokeai.backend.model_manager.load.model_cache.torch_module_autocast.torch_module_autocast import (
+    AUTOCAST_MODULE_TYPE_MAPPING,
+    apply_custom_layers_to_model,
+    remove_custom_layers_from_model,
+)
+from invokeai.backend.util.calc_tensor_size import calc_tensor_size
+from invokeai.backend.util.logging import InvokeAILogger
+
+
+def set_nested_attr(obj: object, attr: str, value: object):
+    """A helper function that extends setattr() to support nested attributes.
+
+    Example:
+        set_nested_attr(model, "module.encoder.conv1.weight", new_conv1_weight)
+    """
+    attrs = attr.split(".")
+    for attr in attrs[:-1]:
+        obj = getattr(obj, attr)
+    setattr(obj, attrs[-1], value)
+
+
+class CachedModelWithPartialLoad:
+    """A wrapper around a PyTorch model to handle partial loads and unloads between the CPU and the compute device.
+
+    Note: "VRAM" is used throughout this class to refer to the memory on the compute device. It could be CUDA memory,
+    MPS memory, etc.
+    """
+
+    def __init__(self, model: torch.nn.Module, compute_device: torch.device):
+        self._model = model
+        self._compute_device = compute_device
+
+        # A CPU read-only copy of the model's state dict.
+        self._cpu_state_dict: dict[str, torch.Tensor] = model.state_dict()
+
+        # TODO(ryand): Handle the case where the model sizes changes after initial load (e.g. due to dtype casting).
+        # Consider how we should handle this for both self._total_bytes and self._cur_vram_bytes.
+        self._total_bytes = sum(calc_tensor_size(p) for p in self._cpu_state_dict.values())
+        self._cur_vram_bytes: int | None = None
+
+        self._modules_that_support_autocast = self._find_modules_that_support_autocast()
+        self._keys_in_modules_that_do_not_support_autocast = self._find_keys_in_modules_that_do_not_support_autocast()
+
+    def _find_modules_that_support_autocast(self) -> dict[str, torch.nn.Module]:
+        """Find all modules that support autocasting."""
+        return {n: m for n, m in self._model.named_modules() if type(m) in AUTOCAST_MODULE_TYPE_MAPPING}
+
+    def _find_keys_in_modules_that_do_not_support_autocast(self) -> set[str]:
+        keys_in_modules_that_do_not_support_autocast = set()
+        for key in self._cpu_state_dict.keys():
+            for module_name in self._modules_that_support_autocast.keys():
+                if key.startswith(module_name):
+                    break
+            else:
+                keys_in_modules_that_do_not_support_autocast.add(key)
+        return keys_in_modules_that_do_not_support_autocast
+
+    @property
+    def model(self) -> torch.nn.Module:
+        return self._model
+
+    def get_cpu_state_dict(self) -> dict[str, torch.Tensor] | None:
+        """Get a read-only copy of the model's state dict in RAM."""
+        # TODO(ryand): Document this better.
+        return self._cpu_state_dict
+
+    def total_bytes(self) -> int:
+        """Get the total size (in bytes) of all the weights in the model."""
+        return self._total_bytes
+
+    def cur_vram_bytes(self) -> int:
+        """Get the size (in bytes) of the weights that are currently in VRAM."""
+        if self._cur_vram_bytes is None:
+            cur_state_dict = self._model.state_dict()
+            self._cur_vram_bytes = sum(
+                calc_tensor_size(p) for p in cur_state_dict.values() if p.device.type == self._compute_device.type
+            )
+        return self._cur_vram_bytes
+
+    def full_load_to_vram(self) -> int:
+        """Load all weights into VRAM."""
+        return self.partial_load_to_vram(self.total_bytes())
+
+    def full_unload_from_vram(self) -> int:
+        """Unload all weights from VRAM."""
+        return self.partial_unload_from_vram(self.total_bytes())
+
+    @torch.no_grad()
+    def partial_load_to_vram(self, vram_bytes_to_load: int) -> int:
+        """Load more weights into VRAM without exceeding vram_bytes_to_load.
+
+        Returns:
+            The number of bytes loaded into VRAM.
+        """
+        # TODO(ryand): Handle the case where an exception is thrown while loading or unloading weights. At the very
+        # least, we should reset self._cur_vram_bytes to None.
+
+        vram_bytes_loaded = 0
+
+        cur_state_dict = self._model.state_dict()
+
+        # First, process the keys *must* be loaded into VRAM.
+        for key in self._keys_in_modules_that_do_not_support_autocast:
+            param = cur_state_dict[key]
+            if param.device.type == self._compute_device.type:
+                continue
+
+            param_size = calc_tensor_size(param)
+            cur_state_dict[key] = param.to(self._compute_device, copy=True)
+            vram_bytes_loaded += param_size
+
+        if vram_bytes_loaded > vram_bytes_to_load:
+            logger = InvokeAILogger.get_logger()
+            logger.warning(
+                f"Loaded {vram_bytes_loaded / 2**20} MB into VRAM, but only {vram_bytes_to_load / 2**20} MB were "
+                "requested. This is the minimum set of weights in VRAM required to run the model."
+            )
+
+        # Next, process the keys that can optionally be loaded into VRAM.
+        fully_loaded = True
+        for key, param in cur_state_dict.items():
+            if param.device.type == self._compute_device.type:
+                continue
+
+            param_size = calc_tensor_size(param)
+            if vram_bytes_loaded + param_size > vram_bytes_to_load:
+                # TODO(ryand): Should we just break here? If we couldn't fit this parameter into VRAM, is it really
+                # worth continuing to search for a smaller parameter that would fit?
+                fully_loaded = False
+                continue
+
+            cur_state_dict[key] = param.to(self._compute_device, copy=True)
+            vram_bytes_loaded += param_size
+
+        if vram_bytes_loaded > 0:
+            # We load the entire state dict, not just the parameters that changed, in case there are modules that
+            # override _load_from_state_dict() and do some funky stuff that requires the entire state dict.
+            # Alternatively, in the future, grouping parameters by module could probably solve this problem.
+            self._model.load_state_dict(cur_state_dict, assign=True)
+
+        if self._cur_vram_bytes is not None:
+            self._cur_vram_bytes += vram_bytes_loaded
+
+        if fully_loaded:
+            remove_custom_layers_from_model(self._model)
+            # TODO(ryand): Warn if the self.cur_vram_bytes() and self.total_bytes() are out of sync.
+        else:
+            apply_custom_layers_to_model(self._model)
+
+        # TODO(ryand): Handle non-persistent buffers.
+        return vram_bytes_loaded
+
+    @torch.no_grad()
+    def partial_unload_from_vram(self, vram_bytes_to_free: int) -> int:
+        """Unload weights from VRAM until vram_bytes_to_free bytes are freed. Or the entire model is unloaded.
+
+        Returns:
+            The number of bytes unloaded from VRAM.
+        """
+        vram_bytes_freed = 0
+
+        offload_device = "cpu"
+        cur_state_dict = self._model.state_dict()
+        for key, param in cur_state_dict.items():
+            if vram_bytes_freed >= vram_bytes_to_free:
+                break
+
+            if param.device.type == offload_device:
+                continue
+
+            cur_state_dict[key] = self._cpu_state_dict[key]
+            vram_bytes_freed += calc_tensor_size(param)
+
+        if vram_bytes_freed > 0:
+            self._model.load_state_dict(cur_state_dict, assign=True)
+
+        if self._cur_vram_bytes is not None:
+            self._cur_vram_bytes -= vram_bytes_freed
+
+        apply_custom_layers_to_model(self._model)
+        return vram_bytes_freed

tests/backend/model_manager/load/model_cache/cached_model/test_cached_model_with_partial_load.py

@@ -0,0 +1,295 @@
+import itertools
+
+import pytest
+import torch
+
+from invokeai.backend.model_manager.load.model_cache.cached_model.cached_model_with_partial_load import (
+    CachedModelWithPartialLoad,
+)
+from invokeai.backend.model_manager.load.model_cache.torch_module_autocast.autocast_modules import CustomLinear
+from invokeai.backend.util.calc_tensor_size import calc_tensor_size
+
+
+class DummyModule(torch.nn.Module):
+    def __init__(self):
+        super().__init__()
+        self.linear1 = torch.nn.Linear(10, 10)
+        self.linear2 = torch.nn.Linear(10, 10)
+        self.register_buffer("buffer1", torch.ones(10, 10))
+
+    def forward(self, x: torch.Tensor) -> torch.Tensor:
+        x = self.linear1(x)
+        x = self.linear2(x)
+        return x
+
+
+parameterize_mps_and_cuda = pytest.mark.parametrize(
+    ("device"),
+    [
+        pytest.param(
+            "mps", marks=pytest.mark.skipif(not torch.backends.mps.is_available(), reason="MPS is not available.")
+        ),
+        pytest.param("cuda", marks=pytest.mark.skipif(not torch.cuda.is_available(), reason="CUDA is not available.")),
+    ],
+)
+
+
+@parameterize_mps_and_cuda
+def test_cached_model_total_bytes(device: str):
+    model = DummyModule()
+    cached_model = CachedModelWithPartialLoad(model=model, compute_device=torch.device(device))
+    linear_numel = 10 * 10 + 10
+    buffer_numel = 10 * 10
+    assert cached_model.total_bytes() == (2 * linear_numel + buffer_numel) * 4
+
+
+@parameterize_mps_and_cuda
+def test_cached_model_cur_vram_bytes(device: str):
+    model = DummyModule()
+    # Model starts in CPU memory.
+    cached_model = CachedModelWithPartialLoad(model=model, compute_device=torch.device(device))
+    assert cached_model.cur_vram_bytes() == 0
+
+    # Full load the model into VRAM.
+    cached_model.full_load_to_vram()
+    assert cached_model.cur_vram_bytes() > 0
+    assert cached_model.cur_vram_bytes() == cached_model.total_bytes()
+    assert all(p.device.type == device for p in model.parameters())
+    assert all(p.device.type == device for p in model.buffers())
+
+
+@parameterize_mps_and_cuda
+def test_cached_model_partial_load(device: str):
+    model = DummyModule()
+    # Model starts in CPU memory.
+    cached_model = CachedModelWithPartialLoad(model=model, compute_device=torch.device(device))
+    model_total_bytes = cached_model.total_bytes()
+    assert cached_model.cur_vram_bytes() == 0
+
+    # Partially load the model into VRAM.
+    target_vram_bytes = int(model_total_bytes * 0.6)
+    loaded_bytes = cached_model.partial_load_to_vram(target_vram_bytes)
+
+    # Check that the model is partially loaded into VRAM.
+    assert loaded_bytes > 0
+    assert loaded_bytes < model_total_bytes
+    assert loaded_bytes == cached_model.cur_vram_bytes()
+    assert loaded_bytes == sum(
+        calc_tensor_size(p) for p in itertools.chain(model.parameters(), model.buffers()) if p.device.type == device
+    )
+
+    # Check that the model's modules have been patched with CustomLinear layers.
+    assert type(model.linear1) is CustomLinear
+    assert type(model.linear2) is CustomLinear
+
+
+@parameterize_mps_and_cuda
+def test_cached_model_partial_unload(device: str):
+    model = DummyModule()
+    # Model starts in CPU memory.
+    cached_model = CachedModelWithPartialLoad(model=model, compute_device=torch.device(device))
+    model_total_bytes = cached_model.total_bytes()
+    assert cached_model.cur_vram_bytes() == 0
+
+    # Full load the model into VRAM.
+    cached_model.full_load_to_vram()
+    assert cached_model.cur_vram_bytes() == model_total_bytes
+
+    # Partially unload the model from VRAM.
+    bytes_to_free = int(model_total_bytes * 0.4)
+    freed_bytes = cached_model.partial_unload_from_vram(bytes_to_free)
+
+    # Check that the model is partially unloaded from VRAM.
+    assert freed_bytes >= bytes_to_free
+    assert freed_bytes < model_total_bytes
+    assert freed_bytes == model_total_bytes - cached_model.cur_vram_bytes()
+    assert freed_bytes == sum(
+        calc_tensor_size(p) for p in itertools.chain(model.parameters(), model.buffers()) if p.device.type == "cpu"
+    )
+
+    # Check that the model's modules are still patched with CustomLinear layers.
+    assert type(model.linear1) is CustomLinear
+    assert type(model.linear2) is CustomLinear
+
+
+@parameterize_mps_and_cuda
+def test_cached_model_full_load_and_unload(device: str):
+    model = DummyModule()
+    cached_model = CachedModelWithPartialLoad(model=model, compute_device=torch.device(device))
+
+    # Model starts in CPU memory.
+    model_total_bytes = cached_model.total_bytes()
+    assert cached_model.cur_vram_bytes() == 0
+
+    # Full load the model into VRAM.
+    loaded_bytes = cached_model.full_load_to_vram()
+    assert loaded_bytes > 0
+    assert loaded_bytes == model_total_bytes
+    assert loaded_bytes == cached_model.cur_vram_bytes()
+    assert all(p.device.type == device for p in itertools.chain(model.parameters(), model.buffers()))
+    assert type(model.linear1) is torch.nn.Linear
+    assert type(model.linear2) is torch.nn.Linear
+
+    # Full unload the model from VRAM.
+    unloaded_bytes = cached_model.full_unload_from_vram()
+
+    # Check that the model is fully unloaded from VRAM.
+    assert unloaded_bytes > 0
+    assert unloaded_bytes == model_total_bytes
+    assert cached_model.cur_vram_bytes() == 0
+    assert all(p.device.type == "cpu" for p in itertools.chain(model.parameters(), model.buffers()))
+
+
+@parameterize_mps_and_cuda
+def test_cached_model_full_load_from_partial(device: str):
+    model = DummyModule()
+    cached_model = CachedModelWithPartialLoad(model=model, compute_device=torch.device(device))
+
+    # Model starts in CPU memory.
+    model_total_bytes = cached_model.total_bytes()
+    assert cached_model.cur_vram_bytes() == 0
+
+    # Partially load the model into VRAM.
+    target_vram_bytes = int(model_total_bytes * 0.6)
+    loaded_bytes = cached_model.partial_load_to_vram(target_vram_bytes)
+    assert loaded_bytes > 0
+    assert loaded_bytes < model_total_bytes
+    assert loaded_bytes == cached_model.cur_vram_bytes()
+    assert type(model.linear1) is CustomLinear
+    assert type(model.linear2) is CustomLinear
+
+    # Full load the rest of the model into VRAM.
+    loaded_bytes_2 = cached_model.full_load_to_vram()
+    assert loaded_bytes_2 > 0
+    assert loaded_bytes_2 < model_total_bytes
+    assert loaded_bytes + loaded_bytes_2 == cached_model.cur_vram_bytes()
+    assert loaded_bytes + loaded_bytes_2 == model_total_bytes
+    assert all(p.device.type == device for p in itertools.chain(model.parameters(), model.buffers()))
+    assert type(model.linear1) is torch.nn.Linear
+    assert type(model.linear2) is torch.nn.Linear
+
+
+@parameterize_mps_and_cuda
+def test_cached_model_full_unload_from_partial(device: str):
+    model = DummyModule()
+    cached_model = CachedModelWithPartialLoad(model=model, compute_device=torch.device(device))
+
+    # Model starts in CPU memory.
+    model_total_bytes = cached_model.total_bytes()
+    assert cached_model.cur_vram_bytes() == 0
+
+    # Partially load the model into VRAM.
+    target_vram_bytes = int(model_total_bytes * 0.6)
+    loaded_bytes = cached_model.partial_load_to_vram(target_vram_bytes)
+    assert loaded_bytes > 0
+    assert loaded_bytes < model_total_bytes
+    assert loaded_bytes == cached_model.cur_vram_bytes()
+
+    # Full unload the model from VRAM.
+    unloaded_bytes = cached_model.full_unload_from_vram()
+    assert unloaded_bytes > 0
+    assert unloaded_bytes == loaded_bytes
+    assert cached_model.cur_vram_bytes() == 0
+    assert all(p.device.type == "cpu" for p in itertools.chain(model.parameters(), model.buffers()))
+
+
+@parameterize_mps_and_cuda
+def test_cached_model_get_cpu_state_dict(device: str):
+    model = DummyModule()
+    cached_model = CachedModelWithPartialLoad(model=model, compute_device=torch.device(device))
+
+    # Model starts in CPU memory.
+    assert cached_model.cur_vram_bytes() == 0
+
+    # The CPU state dict can be accessed and has the expected properties.
+    cpu_state_dict = cached_model.get_cpu_state_dict()
+    assert cpu_state_dict is not None
+    assert len(cpu_state_dict) == len(model.state_dict())
+    assert all(p.device.type == "cpu" for p in cpu_state_dict.values())
+
+    # Full load the model into VRAM.
+    cached_model.full_load_to_vram()
+    assert cached_model.cur_vram_bytes() == cached_model.total_bytes()
+
+    # The CPU state dict is still available, and still on the CPU.
+    cpu_state_dict = cached_model.get_cpu_state_dict()
+    assert cpu_state_dict is not None
+    assert len(cpu_state_dict) == len(model.state_dict())
+    assert all(p.device.type == "cpu" for p in cpu_state_dict.values())
+
+
+@parameterize_mps_and_cuda
+def test_cached_model_full_load_and_inference(device: str):
+    model = DummyModule()
+    cached_model = CachedModelWithPartialLoad(model=model, compute_device=torch.device(device))
+    # Model starts in CPU memory.
+    model_total_bytes = cached_model.total_bytes()
+    assert cached_model.cur_vram_bytes() == 0
+
+    # Run inference on the CPU.
+    x = model(torch.randn(1, 10))
+    output1 = model(x)
+    assert output1.device.type == "cpu"
+
+    # Full load the model into VRAM.
+    loaded_bytes = cached_model.full_load_to_vram()
+    assert loaded_bytes > 0
+    assert loaded_bytes == model_total_bytes
+    assert loaded_bytes == cached_model.cur_vram_bytes()
+    assert all(p.device.type == device for p in itertools.chain(model.parameters(), model.buffers()))
+
+    # Run inference on the GPU.
+    output2 = model(x.to(device))
+    assert output2.device.type == device
+
+    # Full unload the model from VRAM.
+    unloaded_bytes = cached_model.full_unload_from_vram()
+    assert unloaded_bytes > 0
+    assert unloaded_bytes == model_total_bytes
+    assert cached_model.cur_vram_bytes() == 0
+    assert all(p.device.type == "cpu" for p in itertools.chain(model.parameters(), model.buffers()))
+
+    # Run inference on the CPU again.
+    output3 = model(x)
+    assert output3.device.type == "cpu"
+
+    # The outputs should be the same for all three runs.
+    assert torch.allclose(output1, output2.to("cpu"))
+    assert torch.allclose(output1, output3)
+
+
+@parameterize_mps_and_cuda
+def test_cached_model_partial_load_and_inference(device: str):
+    model = DummyModule()
+    # Model starts in CPU memory.
+    cached_model = CachedModelWithPartialLoad(model=model, compute_device=torch.device(device))
+    model_total_bytes = cached_model.total_bytes()
+    assert cached_model.cur_vram_bytes() == 0
+
+    # Run inference on the CPU.
+    x = model(torch.randn(1, 10))
+    output1 = model(x)
+    assert output1.device.type == "cpu"
+
+    # Partially load the model into VRAM.
+    target_vram_bytes = int(model_total_bytes * 0.6)
+    loaded_bytes = cached_model.partial_load_to_vram(target_vram_bytes)
+
+    # Check that the model is partially loaded into VRAM.
+    assert loaded_bytes > 0
+    assert loaded_bytes < model_total_bytes
+    assert loaded_bytes == cached_model.cur_vram_bytes()
+    assert loaded_bytes == sum(
+        calc_tensor_size(p) for p in itertools.chain(model.parameters(), model.buffers()) if p.device.type == device
+    )
+
+    # Check that the model's modules have been patched with CustomLinear layers.
+    assert type(model.linear1) is CustomLinear
+    assert type(model.linear2) is CustomLinear
+
+    # Run inference on the GPU.
+    output2 = model(x.to(device))
+    assert output2.device.type == device
+
+    # The output should be the same as the output from the CPU.
+    assert torch.allclose(output1, output2.to("cpu"))