fix ep_moe_reorder kernel bugs (#6858)

Co-authored-by: JieXin Liang <Alcanderian@users.noreply.github.com>

sgl-kernel/benchmark/bench_moe_ep_pre_reorder.py

-import itertools
-
 import torch
 import triton
-import triton.language as tl
 from sgl_kernel import ep_moe_pre_reorder
 
 from sglang.srt.layers.moe.ep_moe.kernels import pre_reorder_triton_kernel
@@ -25,9 +22,15 @@ configs = [(bs,) for bs in batch_sizes]
     )
 )
 def benchmark(batch_size, provider):
-    dtype = torch.float32
+    dtype = torch.bfloat16
     device = torch.device("cuda")
-    hidden_size, topk, start_expert_id, end_expert_id, block_size = 4096, 8, 0, 255, 512
+    hidden_size, topk, start_expert_id, end_expert_id, block_size = (
+        4096,
+        8,
+        0,
+        255,
+        512,
+    )
 
     # Allocate fresh tensors for every run to match bench_moe_fused_gate style
     def alloc_tensors():
@@ -53,9 +56,9 @@ def benchmark(batch_size, provider):
     quantiles = [0.5, 0.2, 0.8]
 
     if provider == "cuda":
+        inp, gout, s2d, tk_ids, scales = alloc_tensors()
 
         def run_cuda():
-            inp, gout, s2d, tk_ids, scales = alloc_tensors()
             ep_moe_pre_reorder(
                 inp,
                 gout,
@@ -71,9 +74,9 @@ def benchmark(batch_size, provider):
         ms, min_ms, max_ms = triton.testing.do_bench(run_cuda, quantiles=quantiles)
 
     elif provider == "triton":
+        inp, gout, s2d, tk_ids, scales = alloc_tensors()
 
         def run_triton():
-            inp, gout, s2d, tk_ids, scales = alloc_tensors()
             pre_reorder_triton_kernel[(batch_size,)](
                 inp.view(-1),
                 gout.view(-1),

sgl-kernel/csrc/moe/ep_moe_reorder_kernel.cu

@@ -7,9 +7,10 @@
 
 #include "utils.h"
 
+template <typename scalar_t>
 __global__ void ep_pre_reorder_cuda_kernel(
-    const float* __restrict__ input_ptr,
-    float* __restrict__ gateup_input_ptr,
+    const scalar_t* __restrict__ input_ptr,
+    scalar_t* __restrict__ gateup_input_ptr,
     const int* __restrict__ src2dst_ptr,
     const int* __restrict__ topk_ids_ptr,
     const float* __restrict__ a1_scales_ptr,
@@ -21,20 +22,20 @@ __global__ void ep_pre_reorder_cuda_kernel(
   int token_idx = blockIdx.x;
   int tid = threadIdx.x;
 
-  const float* src_ptr = input_ptr + int64_t(token_idx) * hidden_size;
+  const scalar_t* src_ptr = input_ptr + int64_t(token_idx) * hidden_size;
   const int* token_src2dst = src2dst_ptr + token_idx * topk;
   const int* token_topk_ids = topk_ids_ptr + token_idx * topk;
 
-  for (int k = 0; k < topk; ++k) {
-    int expert_id = token_topk_ids[k];
-    if (expert_id < start_expert_id || expert_id > end_expert_id) continue;
-
   float scale = 1.0f;
 
   if (a1_scales_ptr != nullptr and use_per_token_if_dynamic) {
     scale = 1.0f / a1_scales_ptr[token_idx];
   }
 
+  for (int k = 0; k < topk; ++k) {
+    int expert_id = token_topk_ids[k];
+    if (expert_id < start_expert_id || expert_id > end_expert_id) continue;
+
     if (a1_scales_ptr != nullptr) {
       if (!use_per_token_if_dynamic) {
         scale = 1.0f / a1_scales_ptr[expert_id - start_expert_id];
@@ -42,21 +43,27 @@ __global__ void ep_pre_reorder_cuda_kernel(
     }
 
     int dst_idx = token_src2dst[k];
-    float* dst_ptr = gateup_input_ptr + int64_t(dst_idx) * hidden_size;
+    scalar_t* dst_ptr = gateup_input_ptr + int64_t(dst_idx) * hidden_size;
 
-    constexpr uint32_t vec_size = 16 / sizeof(float);
-    using vec_t = flashinfer::vec_t<float, vec_size>;
+    constexpr uint32_t vec_size = 16 / sizeof(scalar_t);
+    using vec_t = flashinfer::vec_t<scalar_t, vec_size>;
 
+    int vec_elements = (hidden_size / vec_size) * vec_size;
     for (int idx = tid; idx < hidden_size / vec_size; idx += blockDim.x) {
       vec_t input_vec, output_vec;
       input_vec.cast_load(src_ptr + idx * vec_size);
 #pragma unroll
       for (uint32_t i = 0; i < vec_size; ++i) {
         float val = static_cast<float>(input_vec[i]);
-        output_vec[i] = val * scale;
+        output_vec[i] = static_cast<scalar_t>(val * scale);
       }
       output_vec.cast_store(dst_ptr + idx * vec_size);
     }
+
+    for (int idx = vec_elements + tid; idx < hidden_size; idx += blockDim.x) {
+      float val = static_cast<float>(src_ptr[idx]);
+      dst_ptr[idx] = static_cast<scalar_t>(val * scale);
+    }
   }
 }
 
@@ -75,9 +82,11 @@ void ep_moe_pre_reorder(
   dim3 grid(total_blocks);
   dim3 block(block_size);
   int hidden_size = input.size(1);
-  ep_pre_reorder_cuda_kernel<<<grid, block>>>(
-      input.data_ptr<float>(),
-      gateup_input.data_ptr<float>(),
+
+  DISPATCH_PYTORCH_DTYPE_TO_CTYPE_FLOAT_FP16(input.scalar_type(), scalar_t, [&] {
+    ep_pre_reorder_cuda_kernel<scalar_t><<<grid, block>>>(
+        static_cast<scalar_t*>(input.data_ptr()),
+        static_cast<scalar_t*>(gateup_input.data_ptr()),
         src2dst.data_ptr<int>(),
         topk_ids.data_ptr<int>(),
         a1_scales.defined() ? a1_scales.data_ptr<float>() : nullptr,
@@ -86,4 +95,6 @@ void ep_moe_pre_reorder(
         topk,
         hidden_size,
         use_per_token_if_dynamic);
+    return true;
+  });
 }

sgl-kernel/tests/test_ep_moe_pre_reorder_kernel.py

+import itertools
+
+import pytest
+import torch
+from sgl_kernel import ep_moe_pre_reorder
+
+from sglang.srt.layers.moe.ep_moe.kernels import pre_reorder_triton_kernel
+
+
+def create_test_tensors(
+    batch_size: int,
+    hidden_size: int,
+    topk: int,
+    start_expert_id: int,
+    end_expert_id: int,
+    dtype: torch.dtype,
+    device: torch.device,
+    use_per_token_if_dynamic: bool = True,
+):
+    input_tensor = torch.randn(batch_size, hidden_size, dtype=dtype, device=device)
+
+    # Ensure src2dst has no duplicate destinations to avoid race conditions
+    total_tokens = batch_size * topk
+    dst_indices = torch.randperm(total_tokens, device=device, dtype=torch.int32)
+    src2dst = dst_indices.view(batch_size, topk)
+
+    topk_ids = torch.randint(
+        start_expert_id,
+        end_expert_id + 1,
+        (batch_size, topk),
+        dtype=torch.int32,
+        device=device,
+    )
+
+    if use_per_token_if_dynamic:
+        a1_scales = (
+            torch.rand(batch_size, dtype=torch.float32, device=device) * 0.8 + 0.2
+        )
+    else:
+        a1_scales = (
+            torch.rand(
+                end_expert_id - start_expert_id + 1, dtype=torch.float32, device=device
+            )
+            * 0.8
+            + 0.2
+        )
+
+    return input_tensor, src2dst, topk_ids, a1_scales
+
+
+def run_cuda_kernel(
+    input_tensor: torch.Tensor,
+    gateup_input: torch.Tensor,
+    src2dst: torch.Tensor,
+    topk_ids: torch.Tensor,
+    a1_scales: torch.Tensor,
+    start_expert_id: int,
+    end_expert_id: int,
+    topk: int,
+    use_per_token_if_dynamic: bool,
+):
+    ep_moe_pre_reorder(
+        input_tensor,
+        gateup_input,
+        src2dst,
+        topk_ids,
+        a1_scales,
+        start_expert_id,
+        end_expert_id,
+        topk,
+        use_per_token_if_dynamic,
+    )
+    return gateup_input
+
+
+def run_triton_kernel(
+    input_tensor: torch.Tensor,
+    gateup_input: torch.Tensor,
+    src2dst: torch.Tensor,
+    topk_ids: torch.Tensor,
+    a1_scales: torch.Tensor,
+    start_expert_id: int,
+    end_expert_id: int,
+    topk: int,
+    hidden_size: int,
+    use_per_token_if_dynamic: bool,
+):
+    batch_size = input_tensor.size(0)
+    block_size = 512
+
+    pre_reorder_triton_kernel[(batch_size,)](
+        input_tensor,
+        gateup_input,
+        src2dst,
+        topk_ids,
+        a1_scales,
+        start_expert_id,
+        end_expert_id,
+        topk,
+        hidden_size,
+        block_size,
+        use_per_token_if_dynamic,
+    )
+    return gateup_input
+
+
+@pytest.mark.parametrize(
+    "batch_size,hidden_size,topk",
+    list(itertools.product([32, 64, 128], [512, 1024, 2048], [4, 8])),
+)
+@pytest.mark.parametrize("dtype", [torch.float16, torch.bfloat16, torch.float32])
+@pytest.mark.parametrize("use_per_token_if_dynamic", [True, False])
+def test_ep_moe_pre_reorder_vs_triton(
+    batch_size: int,
+    hidden_size: int,
+    topk: int,
+    dtype: torch.dtype,
+    use_per_token_if_dynamic: bool,
+):
+    device = torch.device("cuda")
+    start_expert_id = 0
+    end_expert_id = 15
+
+    (
+        input_tensor,
+        src2dst,
+        topk_ids,
+        a1_scales,
+    ) = create_test_tensors(
+        batch_size,
+        hidden_size,
+        topk,
+        start_expert_id,
+        end_expert_id,
+        dtype,
+        device,
+        use_per_token_if_dynamic,
+    )
+
+    gateup_input_cuda = torch.empty(
+        batch_size * topk, hidden_size, dtype=dtype, device=device
+    )
+    gateup_input_triton = torch.empty(
+        batch_size * topk, hidden_size, dtype=dtype, device=device
+    )
+
+    cuda_output = run_cuda_kernel(
+        input_tensor,
+        gateup_input_cuda,
+        src2dst,
+        topk_ids,
+        a1_scales,
+        start_expert_id,
+        end_expert_id,
+        topk,
+        use_per_token_if_dynamic,
+    )
+
+    triton_output = run_triton_kernel(
+        input_tensor,
+        gateup_input_triton,
+        src2dst,
+        topk_ids,
+        a1_scales,
+        start_expert_id,
+        end_expert_id,
+        topk,
+        hidden_size,
+        use_per_token_if_dynamic,
+    )
+
+    torch.testing.assert_close(
+        cuda_output.float(),
+        triton_output.float(),
+        rtol=1e-5,
+        atol=1e-5,
+    )
+
+
+if __name__ == "__main__":
+    pytest.main([__file__])