Generalize Model Size Code (#364)

* Generalize Model Size Code

Summary: previously this worked only on model swap quantized classes and
the version in generate.py was specific to a few cases, this new version
is significantly more general and now consolidated into a single place.

Test Plan: python test_integration.py -k "test_get_model_size"

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Tasks:

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* fix test failures

Summary:

Test Plan:

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Author: HDCharles

test/integration/test_integration.py

@@ -1373,6 +1373,60 @@ def forward(self, x):
         after_export = model(x)
         self.assertTrue(torch.equal(after_export, ref))
 
+class TestUtils(unittest.TestCase):
+    @parameterized.expand(COMMON_DEVICE_DTYPE)
+    @unittest.skipIf(not TORCH_VERSION_AFTER_2_3, "autoquant requires 2.3+.")
+    def test_get_model_size_autoquant(self, device, dtype):
+        if device != "cuda" and dtype != torch.bfloat16:
+            self.skipTest(f"autoquant currently does not support {device}")
+        if device != "cuda" or not torch.cuda.is_available():
+            self.skipTest(f"autoquant currently does not support {device}")
+        if torch.cuda.is_available() and torch.cuda.get_device_capability() < (8, 0):
+            if dtype == torch.bfloat16:
+                self.skipTest(f"bfloat16 requires sm80+")
+        m, k, n = 16, 128, 128
+        model = torch.nn.Sequential(
+            torch.nn.ReLU(),
+            torch.nn.Linear(k,n),
+            torch.nn.ReLU(),
+        ).to(device).to(dtype)
+        example_input = torch.randn(m, k, device=device, dtype=dtype)
+        size = torchao.utils.get_model_size_in_bytes(model)
+
+        from torchao.quantization.autoquant import (
+            AQWeightOnlyQuantizedLinearWeight2,
+        )
+        qtensor_class_list = (
+            AQWeightOnlyQuantizedLinearWeight2,
+
+        )
+
+        mod = torchao.autoquant(torch.compile(model), qtensor_class_list = qtensor_class_list)
+        mod(example_input)
+        size2 = torchao.utils.get_model_size_in_bytes(mod)
+        self.assertTrue(size2 < size)
+
+    @parameterized.expand(
+        list(itertools.product(TENSOR_SUBCLASS_APIS, COMMON_DEVICES, COMMON_DTYPES)),
+    )
+    def test_get_model_size_aqt(self, api, test_device, test_dtype):
+        if test_dtype != torch.bfloat16:
+            self.skipTest(f"{api} in {test_dtype} is not supported yet")
+        if test_device != "cuda" or not torch.cuda.is_available():
+            self.skipTest(f"{api} currently does not support {test_device}")
+        k, n = 1024, 1024
+        model = torch.nn.Sequential(
+            torch.nn.ReLU(),
+            torch.nn.Linear(k,n),
+            torch.nn.ReLU(),
+        ).to(test_device).to(test_dtype)
+        size = torchao.utils.get_model_size_in_bytes(model)
+        api(model)
+        size2 = torchao.utils.get_model_size_in_bytes(model)
+        self.assertTrue(size2 < size)
+        
+
+
 
 if __name__ == "__main__":
     unittest.main()

torchao/_models/llama/generate.py

@@ -13,6 +13,7 @@
 import torchao
 import torch._dynamo.config
 import torch._inductor.config
+from torchao.utils import get_model_size_in_bytes
 
 def device_sync(device):
     if "cuda" in device:
@@ -143,21 +144,6 @@ def _load_model(checkpoint_path, device, precision):
 
     return model.eval()
 
-def _get_model_size(model):
-    model_size = 0
-    for name, child in model.named_children():
-        if not isinstance(child, torch.nn.Embedding):
-            for p in itertools.chain(child.parameters(), child.buffers()):
-                # handling for tensor subclasses
-                if isinstance(p, torchao.dtypes.aqt.AffineQuantizedTensor):
-                    layout_tensor = p.layout_tensor
-                    for attr_name in layout_tensor._tensor_flatten__()[0]:
-                        sub_tensor = getattr(layout_tensor, attr_name)
-                        model_size += sub_tensor.numel() * sub_tensor.element_size()
-                else:
-                    model_size += p.numel() * p.element_size()
-    return model_size
-
 B_INST, E_INST = "[INST]", "[/INST]"
 
 def main(
@@ -226,7 +212,7 @@ def main(
                 interactive=False
             )
 
-    model_size = _get_model_size(model) / 1e9
+    model_size = get_model_size_in_bytes(model, ignore_embeddings=True) / 1e9
 
     if compile:
         global decode_one_token, prefill

torchao/utils.py

@@ -5,6 +5,7 @@
 from math import gcd
 from packaging import version
 import torch.nn.utils.parametrize as parametrize
+import itertools
 
 __all__ = [
     "benchmark_model",
@@ -82,14 +83,31 @@ def find_multiple(n: int, *args: Tuple[int]) -> int:
         return n
     return n + k - (n % k)
 
-# https://discuss.pytorch.org/t/finding-model-size/130275
-def get_model_size_in_bytes(model):
-    s = 0
-    for p in model.parameters():
-        s += p.nelement() * p.element_size()
-    for b in model.buffers():
-        s += b.nelement() * b.element_size()
-    return s
+def get_model_size_in_bytes(model, ignore_embeddings=False):
+    """
+    Returns the model size in bytes. The option to ignore embeddings
+    is useful for models with disproportionately large embeddings compared
+    to other model parameters that get quantized/sparsified.
+    """
+    def flat_size(tensor):
+        if hasattr(tensor, "__tensor_flatten__"):
+            size = 0
+            # 0th element is a list of attributes that
+            # hold tensors
+            for attr_name in tensor.__tensor_flatten__()[0]:
+                sub_tensor = getattr(tensor, attr_name)
+                size += flat_size(sub_tensor)
+            return size
+        else:
+            return tensor.numel() * tensor.element_size()
+
+    model_size = 0
+    for name, child in model.named_children():
+        if not (isinstance(child, torch.nn.Embedding) and ignore_embeddings):
+            for p in itertools.chain(child.parameters(recurse=False), child.buffers(recurse=False)):
+                model_size += flat_size(p)
+            model_size += get_model_size_in_bytes(child, ignore_embeddings)
+    return model_size
 
 class UnwrapTensorSubclass(torch.nn.Module):
     def forward(self, *tensors):