feat: add flops in ModelSummary columns (#20868)

GdoongMathew · sudiptob2 · commit 49b2f4c9ce0a · 2025-06-27T00:25:18.000-04:00
diff --git a/src/lightning/pytorch/callbacks/model_summary.py b/src/lightning/pytorch/callbacks/model_summary.py
@@ -68,13 +68,17 @@ def on_fit_start(self, trainer: "pl.Trainer", pl_module: "pl.LightningModule") -
         model_size = model_summary.model_size
         total_training_modes = model_summary.total_training_modes
 
+        # todo Add `total_flops` in DeepSpeedSummary.
+        total_flops = model_summary.total_flops if hasattr(model_summary, "total_flops") else 0
+
         if trainer.is_global_zero:
             self.summarize(
                 summary_data,
                 total_parameters,
                 trainable_parameters,
                 model_size,
                 total_training_modes,
+                total_flops=total_flops,
                 **self._summarize_kwargs,
             )
 
@@ -92,13 +96,15 @@ def summarize(
         trainable_parameters: int,
         model_size: float,
         total_training_modes: dict[str, int],
+        total_flops: int,
         **summarize_kwargs: Any,
     ) -> None:
         summary_table = _format_summary_table(
             total_parameters,
             trainable_parameters,
             model_size,
             total_training_modes,
+            total_flops,
             *summary_data,
         )
         log.info("\n" + summary_table)
diff --git a/src/lightning/pytorch/callbacks/rich_model_summary.py b/src/lightning/pytorch/callbacks/rich_model_summary.py
@@ -72,6 +72,7 @@ def summarize(
         trainable_parameters: int,
         model_size: float,
         total_training_modes: dict[str, int],
+        total_flops: int,
         **summarize_kwargs: Any,
     ) -> None:
         from rich import get_console
@@ -86,6 +87,7 @@ def summarize(
         table.add_column("Type")
         table.add_column("Params", justify="right")
         table.add_column("Mode")
+        table.add_column("FLOPs", justify="right")
 
         column_names = list(zip(*summary_data))[0]
 
@@ -113,5 +115,6 @@ def summarize(
         grid.add_row(f"[bold]Total estimated model params size (MB)[/]: {parameters[3]}")
         grid.add_row(f"[bold]Modules in train mode[/]: {total_training_modes['train']}")
         grid.add_row(f"[bold]Modules in eval mode[/]: {total_training_modes['eval']}")
+        grid.add_row(f"[bold]Total FLOPs[/]: {get_human_readable_count(total_flops)}")
 
         console.print(grid)
diff --git a/src/lightning/pytorch/utilities/model_summary/model_summary.py b/src/lightning/pytorch/utilities/model_summary/model_summary.py
@@ -22,10 +22,12 @@
 import torch
 import torch.nn as nn
 from torch import Tensor
+from torch.utils.flop_counter import FlopCounterMode
 from torch.utils.hooks import RemovableHandle
 
 import lightning.pytorch as pl
 from lightning.fabric.utilities.distributed import _is_dtensor
+from lightning.fabric.utilities.imports import _TORCH_GREATER_EQUAL_2_4
 from lightning.pytorch.utilities.model_helpers import _ModuleMode
 from lightning.pytorch.utilities.rank_zero import WarningCache
 
@@ -180,29 +182,31 @@ class ModelSummary:
         ...
         >>> model = LitModel()
         >>> ModelSummary(model, max_depth=1)  # doctest: +NORMALIZE_WHITESPACE
-          | Name | Type       | Params | Mode  | In sizes  | Out sizes
-        --------------------------------------------------------------------
-        0 | net  | Sequential | 132 K  | train | [10, 256] | [10, 512]
-        --------------------------------------------------------------------
+          | Name | Type       | Params | Mode  | FLOPs | In sizes  | Out sizes
+        ----------------------------------------------------------------------------
+        0 | net  | Sequential | 132 K  | train | 2.6 M | [10, 256] | [10, 512]
+        ----------------------------------------------------------------------------
         132 K     Trainable params
         0         Non-trainable params
         132 K     Total params
         0.530     Total estimated model params size (MB)
         3         Modules in train mode
         0         Modules in eval mode
+        2.6 M     Total Flops
         >>> ModelSummary(model, max_depth=-1)  # doctest: +NORMALIZE_WHITESPACE
-          | Name  | Type        | Params | Mode  | In sizes  | Out sizes
-        ----------------------------------------------------------------------
-        0 | net   | Sequential  | 132 K  | train | [10, 256] | [10, 512]
-        1 | net.0 | Linear      | 131 K  | train | [10, 256] | [10, 512]
-        2 | net.1 | BatchNorm1d | 1.0 K  | train | [10, 512] | [10, 512]
-        ----------------------------------------------------------------------
+          | Name  | Type        | Params | Mode  | FLOPs | In sizes  | Out sizes
+        ------------------------------------------------------------------------------
+        0 | net   | Sequential  | 132 K  | train | 2.6 M | [10, 256] | [10, 512]
+        1 | net.0 | Linear      | 131 K  | train | 2.6 M | [10, 256] | [10, 512]
+        2 | net.1 | BatchNorm1d | 1.0 K  | train | 0     | [10, 512] | [10, 512]
+        ------------------------------------------------------------------------------
         132 K     Trainable params
         0         Non-trainable params
         132 K     Total params
         0.530     Total estimated model params size (MB)
         3         Modules in train mode
         0         Modules in eval mode
+        2.6 M     Total Flops
 
     """
 
@@ -212,6 +216,13 @@ def __init__(self, model: "pl.LightningModule", max_depth: int = 1) -> None:
         if not isinstance(max_depth, int) or max_depth < -1:
             raise ValueError(f"`max_depth` can be -1, 0 or > 0, got {max_depth}.")
 
+        # The max-depth needs to be plus one because the root module is already counted as depth 0.
+        self._flop_counter = FlopCounterMode(
+            mods=None if _TORCH_GREATER_EQUAL_2_4 else self._model,
+            display=False,
+            depth=max_depth + 1,
+        )
+
         self._max_depth = max_depth
         self._layer_summary = self.summarize()
         # 1 byte -> 8 bits
@@ -279,6 +290,22 @@ def total_layer_params(self) -> int:
     def model_size(self) -> float:
         return self.total_parameters * self._precision_megabytes
 
+    @property
+    def total_flops(self) -> int:
+        return self._flop_counter.get_total_flops()
+
+    @property
+    def flop_counts(self) -> dict[str, dict[Any, int]]:
+        flop_counts = self._flop_counter.get_flop_counts()
+        ret = {
+            name: flop_counts.get(
+                f"{type(self._model).__name__}.{name}",
+                {},
+            )
+            for name in self.layer_names
+        }
+        return ret
+
     def summarize(self) -> dict[str, LayerSummary]:
         summary = OrderedDict((name, LayerSummary(module)) for name, module in self.named_modules)
         if self._model.example_input_array is not None:
@@ -307,8 +334,18 @@ def _forward_example_input(self) -> None:
         mode.capture(model)
         model.eval()
 
+        # FlopCounterMode does not support ScriptModules before torch 2.4.0, so we use a null context
+        flop_context = (
+            contextlib.nullcontext()
+            if (
+                not _TORCH_GREATER_EQUAL_2_4
+                and any(isinstance(m, torch.jit.ScriptModule) for m in self._model.modules())
+            )
+            else self._flop_counter
+        )
+
         forward_context = contextlib.nullcontext() if trainer is None else trainer.precision_plugin.forward_context()
-        with torch.no_grad(), forward_context:
+        with torch.no_grad(), forward_context, flop_context:
             # let the model hooks collect the input- and output shapes
             if isinstance(input_, (list, tuple)):
                 model(*input_)
@@ -330,6 +367,7 @@ def _get_summary_data(self) -> list[tuple[str, list[str]]]:
             ("Type", self.layer_types),
             ("Params", list(map(get_human_readable_count, self.param_nums))),
             ("Mode", ["train" if mode else "eval" for mode in self.training_modes]),
+            ("FLOPs", list(map(get_human_readable_count, (sum(x.values()) for x in self.flop_counts.values())))),
         ]
         if self._model.example_input_array is not None:
             arrays.append(("In sizes", [str(x) for x in self.in_sizes]))
@@ -349,6 +387,7 @@ def _add_leftover_params_to_summary(self, arrays: list[tuple[str, list[str]]], t
         layer_summaries["Type"].append(NOT_APPLICABLE)
         layer_summaries["Params"].append(get_human_readable_count(total_leftover_params))
         layer_summaries["Mode"].append(NOT_APPLICABLE)
+        layer_summaries["FLOPs"].append(NOT_APPLICABLE)
         if "In sizes" in layer_summaries:
             layer_summaries["In sizes"].append(NOT_APPLICABLE)
         if "Out sizes" in layer_summaries:
@@ -361,8 +400,16 @@ def __str__(self) -> str:
         trainable_parameters = self.trainable_parameters
         model_size = self.model_size
         total_training_modes = self.total_training_modes
-
-        return _format_summary_table(total_parameters, trainable_parameters, model_size, total_training_modes, *arrays)
+        total_flops = self.total_flops
+
+        return _format_summary_table(
+            total_parameters,
+            trainable_parameters,
+            model_size,
+            total_training_modes,
+            total_flops,
+            *arrays,
+        )
 
     def __repr__(self) -> str:
         return str(self)
@@ -383,6 +430,7 @@ def _format_summary_table(
     trainable_parameters: int,
     model_size: float,
     total_training_modes: dict[str, int],
+    total_flops: int,
     *cols: tuple[str, list[str]],
 ) -> str:
     """Takes in a number of arrays, each specifying a column in the summary table, and combines them all into one big
@@ -423,6 +471,8 @@ def _format_summary_table(
     summary += "Modules in train mode"
     summary += "\n" + s.format(total_training_modes["eval"], 10)
     summary += "Modules in eval mode"
+    summary += "\n" + s.format(get_human_readable_count(total_flops), 10)
+    summary += "Total Flops"
 
     return summary
 
diff --git a/tests/tests_pytorch/callbacks/test_model_summary.py b/tests/tests_pytorch/callbacks/test_model_summary.py
@@ -65,6 +65,9 @@ def summarize(
             assert summary_data[4][0] == "Mode"
             assert summary_data[4][1][0] == "train"
 
+            assert summary_data[5][0] == "FLOPs"
+            assert all(isinstance(x, str) for x in summary_data[5][1])
+
             assert total_training_modes == {"train": 1, "eval": 0}
 
     model = BoringModel()
diff --git a/tests/tests_pytorch/callbacks/test_rich_model_summary.py b/tests/tests_pytorch/callbacks/test_rich_model_summary.py
@@ -62,10 +62,11 @@ def example_input_array(self) -> Any:
         trainable_parameters=1,
         model_size=1,
         total_training_modes=summary.total_training_modes,
+        total_flops=1,
     )
 
     # ensure that summary was logged + the breakdown of model parameters
     assert mock_console.call_count == 2
     # assert that the input summary data was converted correctly
     args, _ = mock_table_add_row.call_args_list[0]
-    assert args[1:] == ("0", "layer", "Linear", "66  ", "train", "[4, 32]", "[4, 2]")
+    assert args[1:] == ("0", "layer", "Linear", "66  ", "train", "512  ", "[4, 32]", "[4, 2]")
diff --git a/tests/tests_pytorch/utilities/test_model_summary.py b/tests/tests_pytorch/utilities/test_model_summary.py
@@ -173,6 +173,7 @@ def test_empty_model_summary_shapes(max_depth):
     assert summary.in_sizes == []
     assert summary.out_sizes == []
     assert summary.param_nums == []
+    assert summary.total_flops == 0
 
 
 @pytest.mark.parametrize("max_depth", [-1, 1])
