feat: Faster weight processing (moe nvfp4) (#1412)

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Author: aleozlx

flashinfer/fused_moe/core.py

@@ -18,7 +18,7 @@
 from enum import IntEnum
 from pathlib import Path
 from types import SimpleNamespace
-from typing import Any, Dict, List, Optional, Tuple
+from typing import Any, Dict, List, Optional, Tuple, Union
 
 import torch
 
@@ -34,7 +34,13 @@
 from ..jit import env as jit_env
 from ..jit import gen_jit_spec, setup_cubin_loader, sm100a_nvcc_flags
 from ..jit.cutlass_gemm.generate_kernels import generate_gemm_operations
-from ..utils import _check_shape_dtype_device, register_custom_op, register_fake_op
+from ..utils import (
+    _check_shape_dtype_device,
+    get_shuffle_matrix_a_row_indices,
+    get_shuffle_matrix_sf_a_row_indices,
+    register_custom_op,
+    register_fake_op,
+)
 from .utils import (
     get_last_power_of_2_num_tokens_buckets,
     last_positive_power_of_2,
@@ -69,6 +75,56 @@ class WeightLayout(IntEnum):
     BlockMajorK = 2
 
 
+def _maybe_get_cached_w3_w1_permute_indices(
+    _cache_permute_indices,
+    dst_w3_w1_weight: torch.Tensor,
+    epilogue_tile_m: int,
+    num_elts_per_sf: Union[None, int] = None,
+) -> torch.Tensor:
+    if dst_w3_w1_weight.shape not in _cache_permute_indices:
+        # Get permute indices and chain them together
+        permute0 = get_reorder_rows_for_gated_act_gemm_row_indices(dst_w3_w1_weight)
+        if num_elts_per_sf is None:
+            permute1 = get_shuffle_matrix_a_row_indices(
+                dst_w3_w1_weight, epilogue_tile_m=epilogue_tile_m
+            )
+        else:
+            permute1 = get_shuffle_matrix_sf_a_row_indices(
+                dst_w3_w1_weight,
+                epilogue_tile_m=epilogue_tile_m,
+                num_elts_per_sf=num_elts_per_sf,
+            )
+        # Memoize permute indices as recompute is **very** costly
+        _cache_permute_indices[dst_w3_w1_weight.shape] = permute0[permute1].to(
+            dst_w3_w1_weight.device
+        )
+    permute_indices = _cache_permute_indices[dst_w3_w1_weight.shape]
+    return permute_indices
+
+
+def _maybe_get_cached_w2_permute_indices(
+    _cache_permute_indices,
+    dst_w2_weight: torch.Tensor,
+    epilogue_tile_m: int,
+    num_elts_per_sf: Union[None, int] = None,
+) -> torch.Tensor:
+    if dst_w2_weight.shape not in _cache_permute_indices:
+        if num_elts_per_sf is None:
+            permute_indices = get_shuffle_matrix_a_row_indices(
+                dst_w2_weight, epilogue_tile_m
+            ).to(dst_w2_weight.device)
+        else:
+            permute_indices = get_shuffle_matrix_sf_a_row_indices(
+                dst_w2_weight,
+                epilogue_tile_m=epilogue_tile_m,
+                num_elts_per_sf=num_elts_per_sf,
+            ).to(dst_w2_weight.device)
+        # Memoize permute indices as recompute is **very** costly
+        _cache_permute_indices[dst_w2_weight.shape] = permute_indices
+    permute_indices = _cache_permute_indices[dst_w2_weight.shape]
+    return permute_indices
+
+
 def get_reorder_rows_for_gated_act_gemm_row_indices(x) -> torch.Tensor:
     """
     Reorders rows in the gemm/MOE_gemm weight matrix for min-latency

tests/test_trtllm_gen_fused_moe.py

@@ -16,7 +16,7 @@
 
 from abc import ABC, abstractmethod
 from enum import IntEnum
-from typing import Literal
+from typing import Dict, Literal
 
 import pytest
 import torch
@@ -30,15 +30,19 @@
     next_positive_power_of_2,
     reorder_rows_for_gated_act_gemm,
     shuffle_matrix_a,
-    shuffle_matrix_sf_a,
 )
+from flashinfer.fp4_quantization import nvfp4_block_scale_interleave
 from flashinfer.fused_moe import (
     WeightLayout,
     convert_to_block_layout,
     trtllm_fp4_block_scale_moe,
     trtllm_fp8_block_scale_moe,
     trtllm_fp8_per_tensor_scale_moe,
 )
+from flashinfer.fused_moe.core import (
+    _maybe_get_cached_w2_permute_indices,
+    _maybe_get_cached_w3_w1_permute_indices,
+)
 
 
 def check_cuda(err):
@@ -386,50 +390,67 @@ def prepare_static_weights_for_kernel(
             num_experts, hidden_size, intermediate_size // 16
         )  # fp8 scaling factors
 
-        # Reorder rows of W1 and scales for fused gated activation
-        gemm1_weights_fp4_interleaved = []
-        gemm1_scales_fp4_interleaved = []
-        for i in range(num_experts):
-            gemm1_weights_fp4_interleaved.append(
-                reorder_rows_for_gated_act_gemm(gemm1_weights_fp4[i].clone())
-            )
-            gemm1_scales_fp4_interleaved.append(
-                reorder_rows_for_gated_act_gemm(gemm1_scales_linear_fp4[i].clone())
-            )
-
-        # Stack weights and scales for all experts
-        gemm1_weights_fp4_interleaved = torch.stack(
-            gemm1_weights_fp4_interleaved
-        ).reshape(num_experts, 2 * intermediate_size, hidden_size // 2)
-        gemm1_scales_fp4_interleaved = torch.stack(
-            gemm1_scales_fp4_interleaved
-        ).reshape(num_experts, 2 * intermediate_size, hidden_size // 16)
-
-        # Shuffle weights and scaling factors for transposed mma output
+        # Using cached permute index calculation can speed up weights preprocessing
         gemm1_weights_fp4_shuffled = []
         gemm1_scales_fp4_shuffled = []
         gemm2_weights_fp4_shuffled = []
         gemm2_scales_fp4_shuffled = []
         for i in range(num_experts):
+            # Calculate the permute indices for the following:
+            # 1. Reorder rows of W1 and scales for fused gated activation
+            # 2. Shuffle weights and scaling factors for transposed mma output
+            # for both w3_w1 and w2 weights and scale factors
+            permute_indices = _maybe_get_cached_w3_w1_permute_indices(
+                self._cache_permute_indices,
+                gemm1_weights_fp4[i].view(torch.uint8),
+                epilogue_tile_m,
+            )
             gemm1_weights_fp4_shuffled.append(
-                shuffle_matrix_a(
-                    gemm1_weights_fp4_interleaved[i].view(torch.uint8), epilogue_tile_m
-                )
+                gemm1_weights_fp4[i]
+                .view(torch.uint8)[permute_indices.to(gemm1_weights_fp4.device)]
+                .contiguous()
+            )
+
+            permute_sf_indices = _maybe_get_cached_w3_w1_permute_indices(
+                self._cache_permute_indices,
+                gemm1_scales_linear_fp4[i].view(torch.uint8),
+                epilogue_tile_m,
+                num_elts_per_sf=16,
             )
             gemm1_scales_fp4_shuffled.append(
-                shuffle_matrix_sf_a(
-                    gemm1_scales_fp4_interleaved[i].view(torch.uint8), epilogue_tile_m
+                nvfp4_block_scale_interleave(
+                    gemm1_scales_linear_fp4[i]
+                    .view(torch.uint8)[
+                        permute_sf_indices.to(gemm1_scales_linear_fp4.device)
+                    ]
+                    .contiguous()
                 )
             )
 
+            permute_indices = _maybe_get_cached_w2_permute_indices(
+                self._cache_permute_indices,
+                gemm2_weights_fp4[i].view(torch.uint8),
+                epilogue_tile_m,
+            )
             gemm2_weights_fp4_shuffled.append(
-                shuffle_matrix_a(
-                    gemm2_weights_fp4[i].view(torch.uint8), epilogue_tile_m
-                )
+                gemm2_weights_fp4[i]
+                .view(torch.uint8)[permute_indices.to(gemm2_weights_fp4.device)]
+                .contiguous()
+            )
+
+            permute_sf_indices = _maybe_get_cached_w2_permute_indices(
+                self._cache_permute_indices,
+                gemm2_scales_linear_fp4[i].view(torch.uint8),
+                epilogue_tile_m,
+                num_elts_per_sf=16,
             )
             gemm2_scales_fp4_shuffled.append(
-                shuffle_matrix_sf_a(
-                    gemm2_scales_linear_fp4[i].view(torch.uint8), epilogue_tile_m
+                nvfp4_block_scale_interleave(
+                    gemm2_scales_linear_fp4[i]
+                    .view(torch.uint8)[
+                        permute_sf_indices.to(gemm2_scales_linear_fp4.device)
+                    ]
+                    .contiguous()
                 )
             )
 
@@ -1627,6 +1648,12 @@ def calculate_tile_tokens_dim(num_tokens: int, num_experts: int, top_k: int) ->
     return tile_tokens_dim
 
 
+@pytest.fixture(scope="module")
+def cache_permute_indices():
+    _cache_permute_indices: Dict[torch.Size, torch.Tensor] = {}
+    return _cache_permute_indices
+
+
 @pytest.mark.parametrize("num_tokens", [1, 1024])
 @pytest.mark.parametrize("hidden_size", [1024])
 @pytest.mark.parametrize("intermediate_size", [1024, 768, 384])
@@ -1758,6 +1785,7 @@ def test_moe_quantization_classes(
     moe_impl,
     routing_config,
     weight_processing,
+    cache_permute_indices,
 ):
     """
     Test MoE implementations using separated quantization workflow.
@@ -1778,6 +1806,8 @@ def test_moe_quantization_classes(
             f"Incompatible: {moe_impl.name} + {weight_processing['use_shuffled_weight']} + {weight_processing['layout']}"
         )
 
+    moe_impl._cache_permute_indices = cache_permute_indices
+
     seed = 0
     torch.random.manual_seed(seed)