move float8_experimental to torchao/float8

Summary:

This PR moves https://github.com/pytorch-labs/float8_experimental to
torchao/float8.

There are no logic changes here. Here is how to reproduce this PR:
* copy float8_experimental/float8_experimental/* to torchao/float8
* copy float8_experimental/test/* to test/float8
* copy float8_experimental/benchmarks/* to benchmarks/float8
* copy the README over and delete sections which no longer apply
  (license, installation)
* replace `float8_experimental` with `torchao.float8` everywhere

Test Plan:

```
// run local tests, they pass
./test/float8/test_everything.sh

// run every benchmark in `benchmarks/float8`, they still work
```

Reviewers:

Subscribers:

Tasks:

Tags:

Author: vkuzo

README.md

@@ -85,6 +85,12 @@ In some cases we rewrote popular GenAI models to be significantly faster in nati
 
 ### Training
 
+#### Float8
+
+[torchao.float8](torchao/float8) implements training recipes with the scaled float8 dtypes, as laid out in https://arxiv.org/abs/2209.05433.
+
+#### Sparsity
+
 We've added support for semi-structured 2:4 sparsity with 6% end to end speedups on ViT-L
 
 The code change is a 1 liner with the full example available [here](torchao/sparsity/training/)

benchmarks/float8/bench_linear_float8.py

@@ -0,0 +1,307 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD 3-Clause license found in the
+# LICENSE file in the root directory of this source tree.
+import argparse
+import copy
+from dataclasses import dataclass
+from itertools import product
+from pathlib import Path
+from typing import Callable, List, Optional, Tuple
+
+import pandas as pd
+
+import torch
+import torch.utils.benchmark as benchmark
+from torchao.float8.config import CastConfig, Float8LinearConfig, ScalingType
+from torchao.float8.float8_linear import Float8Linear
+from torchao.float8.float8_linear_utils import (
+    linear_requires_sync,
+    sync_float8_amax_and_scale_history,
+)
+from torchao.float8.float8_tensor import ScaledMMConfig
+from tqdm import tqdm
+
+# estimating TOPs for matmuls in fp32, fp16, fp8
+# assuming A * B = C, with A being M * K, B being K * N, C being M * N
+
+# H100 SXM specs: bottom of https://www.nvidia.com/en-us/data-center/h100/
+h100_peak_flops_float32 = 67e12
+h100_peak_flops_fp16_tc = 1979e12
+h100_peak_tops_float8_tc = 3958e12
+
+dtype_to_peak_tops = {
+    torch.float32: h100_peak_flops_float32,
+    torch.float16: h100_peak_flops_fp16_tc,
+    torch.bfloat16: h100_peak_flops_fp16_tc,
+    torch.float8_e4m3fn: h100_peak_tops_float8_tc,
+    torch.float8_e5m2: h100_peak_tops_float8_tc,
+}
+
+# prevent splitting columns when printing a data frame
+pd.set_option("display.expand_frame_repr", False)
+# print the entire data frame
+pd_print_full_ctx = pd.option_context(
+    "display.max_rows", None, "display.max_columns", None
+)
+
+
+def benchmark_torch_function_in_microseconds(
+    func: Callable,
+    *args,
+    **kwargs,
+) -> float:
+    t0 = benchmark.Timer(
+        stmt="func(*args, **kwargs)",
+        globals={"args": args, "kwargs": kwargs, "func": func},
+    )
+    return t0.blocked_autorange().median * 1e6
+
+
+@dataclass
+class Experiment:
+    name: str
+    shape: Tuple[int, int, int]
+    ref_time_sec: float
+    float8_time_sec: float
+    dtype: torch.dtype
+    compiled: bool
+    use_fast_accum: bool
+    scaling_repr: str
+
+    # 3 Times since we are calculating forward backward
+    @property
+    def ref_tops_sec(self):
+        M, K, N = self.shape
+        return float(3 * (2 * M * K * N)) / self.ref_time_sec
+
+    @property
+    def ref_pct_top_peak(self):
+        return self.ref_tops_sec / dtype_to_peak_tops[self.dtype]
+
+    @property
+    def float8_tops_sec(self):
+        M, K, N = self.shape
+        return float(3 * (2 * M * K * N)) / self.float8_time_sec
+
+    @property
+    def float8_pct_top_peak(self):
+        return self.float8_tops_sec / dtype_to_peak_tops[torch.float8_e4m3fn]
+
+
+def main(
+    sweep_path: Optional[Path] = None,
+    compile: bool = True,
+    n_limit: Optional[int] = None,
+    fast_accum_filter: Optional[bool] = None,
+    shape_name_filter: Optional[str] = None,
+    scaling_type_input: str = "dynamic",
+    scaling_type_weight: str = "dynamic",
+    scaling_type_grad_output: str = "dynamic",
+):
+    device = "cuda"
+    print(f"Compile is set to             | {compile}")
+
+    scaling_type_input = ScalingType(scaling_type_input)
+    scaling_type_weight = ScalingType(scaling_type_weight)
+    scaling_type_grad_output = ScalingType(scaling_type_grad_output)
+    config = Float8LinearConfig(
+        cast_config_input=CastConfig(scaling_type=scaling_type_input),
+        cast_config_weight=CastConfig(scaling_type=scaling_type_weight),
+        cast_config_grad_output=CastConfig(scaling_type=scaling_type_grad_output),
+    )
+
+    # LLaMa 2 70B single-node weight shapes
+    # assumes fused attn.wqkv and ffn.w13
+    name_to_shapes_70b = {
+        "attn.wqkv": (8192, 1280),
+        "attn.w0": (1024, 8192),
+        "ffn.w13": (8192, 7168),
+        "ffn.w2": (3584, 8192),
+    }
+    input_bias = False
+    if fast_accum_filter is not None:
+        use_fast_accum = [fast_accum_filter]
+    else:
+        use_fast_accum = [True, False]
+    if shape_name_filter is not None:
+        k = shape_name_filter
+        name_to_shapes_70b = {k: name_to_shapes_70b[k]}
+    experiment_list: List[Experiment] = []
+    dtype = torch.bfloat16
+    for idx, (fast_accum, (name, (K, N))) in enumerate(
+        tqdm(list(product(use_fast_accum, name_to_shapes_70b.items())))
+    ):
+        if n_limit is not None and idx >= n_limit:
+            break
+        linear_ref = torch.nn.Linear(K, N, bias=input_bias).to(
+            device=device, dtype=dtype
+        )
+
+        linear_float8 = Float8Linear.from_float(
+            copy.deepcopy(linear_ref),
+            config=config,
+        )
+        scaling_repr = linear_float8.scaling_repr()
+
+        if fast_accum:
+            linear_float8.forward_config = ScaledMMConfig(False, True, False)
+        else:
+            linear_float8.forward_config = ScaledMMConfig(False, False, False)
+
+        bsz, seq_len = 4, 4096
+        M = bsz * seq_len
+        input_tensor = torch.randn(M, K, device=device, dtype=dtype, requires_grad=True)
+        ref_forw_backward = lambda: linear_ref(input_tensor).sum().backward()
+
+        def float8_forw_backward():
+            if linear_requires_sync(config):
+                sync_float8_amax_and_scale_history(linear_float8)
+            linear_float8(input_tensor).sum().backward()
+
+        def n_times(n, fn, *args, **kwargs):
+            def wrapper(*args, **kwargs):
+                for _ in range(n):
+                    fn(*args, **kwargs)
+
+            return wrapper
+
+        REPEAT_N = 100
+
+        ref_forw_backward = n_times(REPEAT_N, ref_forw_backward)
+        float8_forw_backward = n_times(REPEAT_N, float8_forw_backward)
+
+        if compile:
+            ref_forw_backward = torch.compile(ref_forw_backward)
+            float8_forw_backward = torch.compile(float8_forw_backward)
+
+        for _ in range(5):
+            ref_forw_backward()
+            float8_forw_backward()
+
+        ref_time = (
+            benchmark_torch_function_in_microseconds(ref_forw_backward)
+            * 1e-6
+            / REPEAT_N
+        )
+        float8_time = (
+            benchmark_torch_function_in_microseconds(float8_forw_backward)
+            * 1e-6
+            / REPEAT_N
+        )
+        experiment = Experiment(
+            name,
+            (M, K, N),
+            ref_time,
+            float8_time,
+            dtype,
+            compile,
+            use_fast_accum=fast_accum,
+            scaling_repr=scaling_repr,
+        )
+        print(experiment)
+        print("float8 speedup", experiment.ref_time_sec / experiment.float8_time_sec)
+        experiment_list.append(experiment)
+        torch._dynamo.reset()
+
+    headers = [
+        "name",
+        "M",
+        "K",
+        "N",
+        "scaling_repr",
+        "ref_dtype",
+        "compiled",
+        "use_fast_accum",
+        "ref_time_sec",
+        "pt_fp8_time_sec",
+        "ref_tops_sec",
+        "ref_pct_top_peak",
+        "pt_fp8_tops_sec",
+        "pt_fp8_pct_top_peak",
+    ]
+    data = []
+    for experiment in experiment_list:
+        data.append(
+            [
+                experiment.name,
+                experiment.shape[0],
+                experiment.shape[1],
+                experiment.shape[2],
+                experiment.scaling_repr,
+                experiment.dtype,
+                experiment.compiled,
+                experiment.use_fast_accum,
+                experiment.ref_time_sec,
+                experiment.float8_time_sec,
+                experiment.ref_tops_sec,
+                experiment.ref_pct_top_peak,
+                experiment.float8_tops_sec,
+                experiment.float8_pct_top_peak,
+            ]
+        )
+
+    data_pd = pd.DataFrame(data, columns=headers)
+    data_pd["pt_fp8_speedup"] = data_pd["ref_time_sec"] / data_pd["pt_fp8_time_sec"]
+    data_pd["shape"] = (
+        "("
+        + data_pd["M"].astype(str)
+        + ", "
+        + data_pd["K"].astype(str)
+        + ", "
+        + data_pd["N"].astype(str)
+        + ")"
+    )
+
+    data_pd_simple = data_pd[
+        [
+            "name",
+            "shape",
+            "scaling_repr",
+            "compiled",
+            "use_fast_accum",
+            "ref_time_sec",
+            "pt_fp8_time_sec",
+            "pt_fp8_speedup",
+        ]
+    ]
+    with pd_print_full_ctx:
+        print(data_pd_simple)
+
+    if sweep_path is not None:
+        sweep_path = sweep_path.with_suffix(".csv")
+        data_pd.to_csv(sweep_path)
+
+
+def invoke_main() -> None:
+    parser = argparse.ArgumentParser()
+    parser.add_argument("-o", "--output_path", type=str, required=False)
+    parser.add_argument("--disable_compile", action="store_true")
+    parser.add_argument("-n", "--n_limit", type=int, required=False)
+    parser.add_argument("--fast_accum_filter", type=bool, required=False)
+    parser.add_argument("--shape_name_filter", type=str, required=False)
+    parser.add_argument("--scaling_type_input", type=str, required=False)
+    parser.add_argument("--scaling_type_weight", type=str, required=False)
+    parser.add_argument("--scaling_type_grad_output", type=str, required=False)
+    args = parser.parse_args()
+    output_path = Path(args.output_path) if args.output_path is not None else None
+    kwargs = {}
+    if args.scaling_type_input is not None:
+        kwargs["scaling_type_input"] = args.scaling_type_input
+    if args.scaling_type_weight is not None:
+        kwargs["scaling_type_weight"] = args.scaling_type_weight
+    if args.scaling_type_grad_output is not None:
+        kwargs["scaling_type_grad_output"] = args.scaling_type_grad_output
+    main(
+        output_path,
+        not args.disable_compile,
+        args.n_limit,
+        args.fast_accum_filter,
+        args.shape_name_filter,
+        **kwargs,
+    )
+
+
+if __name__ == "__main__":
+    invoke_main()  # pragma: no cover