[torch.compile] Dynamic fp8 + rms_norm fusion (vllm-project#10906)

Signed-off-by: luka <[email protected]>
Co-authored-by: Varun Sundar Rabindranath <[email protected]>

CMakeLists.txt

@@ -196,6 +196,7 @@ set(VLLM_EXT_SRC
   "csrc/quantization/gptq/q_gemm.cu"
   "csrc/quantization/compressed_tensors/int8_quant_kernels.cu"
   "csrc/quantization/fp8/common.cu"
+  "csrc/quantization/fused_kernels/fused_layernorm_dynamic_per_token_quant.cu"
   "csrc/quantization/gguf/gguf_kernel.cu"
   "csrc/cuda_utils_kernels.cu"
   "csrc/prepare_inputs/advance_step.cu"
@@ -300,7 +301,7 @@ if(VLLM_GPU_LANG STREQUAL "CUDA")
   #
   # For the cutlass_scaled_mm kernels we want to build the c2x (CUTLASS 2.x)
   # kernels for the remaining archs that are not already built for 3x.
-  cuda_archs_loose_intersection(SCALED_MM_2X_ARCHS 
+  cuda_archs_loose_intersection(SCALED_MM_2X_ARCHS
     "7.5;8.0;8.6;8.7;8.9;9.0" "${CUDA_ARCHS}")
   # subtract out the archs that are already built for 3x
   list(REMOVE_ITEM SCALED_MM_2X_ARCHS ${SCALED_MM_3X_ARCHS})

benchmarks/fused_kernels/layernorm_rms_benchmarks.py

@@ -0,0 +1,173 @@
+import pickle as pkl
+import time
+from dataclasses import dataclass
+from itertools import product
+from typing import Callable, Iterable, List, Optional
+
+import torch
+import torch.utils.benchmark as TBenchmark
+from torch.utils.benchmark import Measurement as TMeasurement
+from tqdm import tqdm
+
+import vllm._custom_ops as ops
+from vllm.model_executor.layers.layernorm import RMSNorm
+
+
+@dataclass
+class bench_params_t:
+    num_tokens: int
+    hidden_size: int
+    add_residual: bool
+    dtype: torch.dtype
+
+    def description(self):
+        return (f'N {self.num_tokens} '
+                f'x D {self.hidden_size} '
+                f'x R {self.add_residual} '
+                f'x DT {self.dtype}')
+
+
+def get_bench_params() -> List[bench_params_t]:
+    ## Test Fixtures
+    NUM_TOKENS = [2**x for x in range(11)]
+    HIDDEN_SIZES = list(range(1024, 8129, 1024))
+    ADD_RESIDUAL = [True, False]
+    DTYPES = [torch.bfloat16, torch.float]
+
+    combinations = product(NUM_TOKENS, HIDDEN_SIZES, ADD_RESIDUAL, DTYPES)
+    bench_params = list(map(lambda x: \
+        bench_params_t(x[0], x[1], x[2], x[3]), combinations))
+    return bench_params
+
+
+# Reference impls
+def unfused_int8_impl(rms_norm_layer: RMSNorm, x: torch.Tensor,
+                      residual: Optional[torch.Tensor],
+                      quant_dtype: torch.dtype):
+    # Norm
+    torch_out = None
+    if residual is None:
+        torch_out = rms_norm_layer.forward_cuda(x, residual)
+    else:
+        torch_out, _ = rms_norm_layer.forward_cuda(x, residual)
+
+    # Quant
+    torch_out, _, _ = ops.scaled_int8_quant(torch_out)
+
+
+def unfused_fp8_impl(rms_norm_layer: RMSNorm, x: torch.Tensor,
+                     residual: Optional[torch.Tensor],
+                     quant_dtype: torch.dtype):
+    # Norm
+    torch_out = None
+    if residual is None:
+        torch_out = rms_norm_layer.forward_cuda(x, residual)
+    else:
+        torch_out, _ = rms_norm_layer.forward_cuda(x, residual)
+
+    # Quant
+    torch_out, _ = ops.scaled_fp8_quant(torch_out)
+
+
+def fused_impl(
+        rms_norm_layer: RMSNorm,  # this stores the weights
+        x: torch.Tensor,
+        residual: Optional[torch.Tensor],
+        quant_dtype: torch.dtype):
+    out, _ = ops.rms_norm_dynamic_per_token_quant(x,
+                                                  rms_norm_layer.weight,
+                                                  1e-6,
+                                                  quant_dtype,
+                                                  residual=residual)
+
+
+# Bench functions
+def bench_fn(rms_norm_layer: RMSNorm, x: torch.Tensor, residual: torch.Tensor,
+             quant_dtype: torch.dtype, label: str, sub_label: str,
+             fn: Callable, description: str) -> TMeasurement:
+
+    min_run_time = 1
+
+    globals = {
+        "rms_norm_layer": rms_norm_layer,
+        "x": x,
+        "residual": residual,
+        "quant_dtype": quant_dtype,
+        "fn": fn,
+    }
+    return TBenchmark.Timer(
+        stmt="fn(rms_norm_layer, x, residual, quant_dtype)",
+        globals=globals,
+        label=label,
+        sub_label=sub_label,
+        description=description,
+    ).blocked_autorange(min_run_time=min_run_time)
+
+def bench(params: bench_params_t, label: str, sub_label: str) \
+        -> Iterable[TMeasurement]:
+
+    # Make inputs
+    layer = RMSNorm(params.hidden_size, 1e-6).to(dtype=params.dtype)
+    # Make weights
+    layer.weight.data.normal_(mean=1.0, std=0.1)
+    # Make inputs
+    scale = 1 / params.hidden_size
+    x = torch.randn(params.num_tokens,
+                    params.hidden_size,
+                    dtype=params.dtype,
+                    device='cuda') * scale
+    residual = (torch.randn_like(x) * scale).to(device='cuda') \
+            if params.add_residual else None
+
+    timers = []
+
+    # unfused int8 impl.
+    timers.append(
+        bench_fn(layer, x, residual, torch.int8, label, sub_label,
+                 unfused_int8_impl, "unfused_int8_impl"))
+
+    # unfused fp8 impl.
+    timers.append(
+        bench_fn(layer, x, residual, torch.float8_e4m3fn, label, sub_label,
+                 unfused_fp8_impl, "unfused_fp8_impl"))
+
+    # fused int8 impl.
+    timers.append(
+        bench_fn(layer, x, residual, torch.int8, label, sub_label, fused_impl,
+                 "fused_int8_impl"))
+
+    # fused fp8 impl.
+    timers.append(
+        bench_fn(layer, x, residual, torch.float8_e4m3fn, label, sub_label,
+                 fused_impl, "fused_fp8_impl"))
+
+    print_timers(timers)
+
+    return timers
+
+
+# launch bench
+# runner
+def print_timers(timers: Iterable[TMeasurement]):
+    compare = TBenchmark.Compare(timers)
+    compare.print()
+
+
+def main():
+    torch.set_default_device('cuda')
+    bench_params = get_bench_params()
+
+    timers = []
+    for bp in tqdm(bench_params):
+        timers.extend(
+            bench(bp, "rms-norm-dynamic-per-token-quant", bp.description()))
+    print_timers(timers)
+
+    # pickle all the results
+    timestamp = int(time.time())
+    with open(f"rms_norm_dpt_quant-{timestamp}.pkl", "wb") as f:
+        pkl.dump(timers, f)
+
+
+if __name__ == '__main__':
+    main()

csrc/dispatch_utils.h

@@ -14,6 +14,20 @@
 #define VLLM_DISPATCH_FLOATING_TYPES(TYPE, NAME, ...) \
   AT_DISPATCH_SWITCH(TYPE, NAME, VLLM_DISPATCH_CASE_FLOATING_TYPES(__VA_ARGS__))
 
+// TODO(luka/varun): use FP8_TYPE macro after refactoring
+#ifndef USE_ROCM
+  #define VLLM_DISPATCH_CASE_QUANT_TYPES(...)                    \
+    AT_DISPATCH_CASE(at::ScalarType::Float8_e4m3fn, __VA_ARGS__) \
+    AT_DISPATCH_CASE(at::ScalarType::Char, __VA_ARGS__)
+#else
+  #define VLLM_DISPATCH_CASE_QUANT_TYPES(...)                      \
+    AT_DISPATCH_CASE(at::ScalarType::Float8_e4m3fnuz, __VA_ARGS__) \
+    AT_DISPATCH_CASE(at::ScalarType::Char, __VA_ARGS__)
+#endif
+
+#define VLLM_DISPATCH_QUANT_TYPES(TYPE, NAME, ...) \
+  AT_DISPATCH_SWITCH(TYPE, NAME, VLLM_DISPATCH_CASE_QUANT_TYPES(__VA_ARGS__))
+
 #define VLLM_DISPATCH_CASE_FLOATING_AND_BYTE_TYPES(...)   \
   AT_DISPATCH_CASE(at::ScalarType::Float, __VA_ARGS__)    \
   AT_DISPATCH_CASE(at::ScalarType::Half, __VA_ARGS__)     \

csrc/ops.h

@@ -66,6 +66,14 @@ void fused_add_rms_norm_static_fp8_quant(torch::Tensor& out,
                                          torch::Tensor& weight,
                                          torch::Tensor& scale, double epsilon);
 
+void rms_norm_dynamic_per_token_quant(torch::Tensor& out,
+                                      torch::Tensor const& input,
+                                      torch::Tensor const& weight,
+                                      torch::Tensor& scales,
+                                      double const epsilon,
+                                      std::optional<torch::Tensor> scale_ub,
+                                      std::optional<torch::Tensor> residual);
+
 void rotary_embedding(torch::Tensor& positions, torch::Tensor& query,
                       torch::Tensor& key, int64_t head_size,
                       torch::Tensor& cos_sin_cache, bool is_neox);

csrc/quantization/fp8/common.cuh

@@ -1,6 +1,9 @@
 #pragma once
 
+#include "quantization/vectorization.cuh"
+
 #include <cmath>
+#include <c10/core/ScalarType.h>
 
 #ifndef USE_ROCM
   #include <c10/util/Float8_e4m3fn.h>
@@ -15,6 +18,7 @@ using FP8_TYPE = c10::Float8_e4m3fnuz;
 // issue when running dynamic quantization. Here use 224.0f for rocm.
 constexpr auto FP8_E4M3_MAX = 224.0f;
 #endif
+constexpr static auto kFp8Type = c10::CppTypeToScalarType<FP8_TYPE>::value;
 
 namespace vllm {
 
@@ -89,22 +93,6 @@ __global__ void segmented_max_reduction(float* __restrict__ scale,
   }
 }
 
-template <typename scalar_t>
-struct __align__(8) vec4_t {
-  scalar_t x;
-  scalar_t y;
-  scalar_t z;
-  scalar_t w;
-};
-
-typedef struct __align__(4) {
-  FP8_TYPE x;
-  FP8_TYPE y;
-  FP8_TYPE z;
-  FP8_TYPE w;
-}
-float8x4_t;
-
 template <typename scalar_t>
 __device__ float thread_max_vec(scalar_t const* __restrict__ input,
                                 int64_t const num_elems, int const tid,
@@ -139,10 +127,10 @@ __device__ void scaled_fp8_conversion_vec(FP8_TYPE* __restrict__ out,
                                           float const scale,
                                           int64_t const num_elems,
                                           int const tid, int const step) {
+  using float8x4_t = q8x4_t<FP8_TYPE>;
   // Vectorized input/output to better utilize memory bandwidth.
-  vec4_t<scalar_t> const* vectorized_in =
-      reinterpret_cast<vec4_t<scalar_t> const*>(input);
-  float8x4_t* vectorized_out = reinterpret_cast<float8x4_t*>(out);
+  auto const* vectorized_in = reinterpret_cast<vec4_t<scalar_t> const*>(input);
+  auto* vectorized_out = reinterpret_cast<float8x4_t*>(out);
 
   int64_t const num_vec_elems = num_elems >> 2;