Add dsv3 router gemm kernel (#7627)

sgl-kernel/tests/test_dsv3_router_gemm.py

@@ -0,0 +1,32 @@
+import pytest
+import torch
+import torch.nn.functional as F
+from sgl_kernel import dsv3_router_gemm
+
+
+@pytest.mark.parametrize("num_tokens", [i + 1 for i in range(16)])
+def test_dsv3_router_gemm(num_tokens):
+    num_experts = 256
+    hidden_dim = 7168
+
+    mat_a = torch.randn(
+        (num_tokens, hidden_dim), dtype=torch.bfloat16, device="cuda"
+    ).contiguous()
+    mat_b = torch.randn(
+        (num_experts, hidden_dim), dtype=torch.bfloat16, device="cuda"
+    ).contiguous()
+    output = torch.empty(
+        (num_tokens, num_experts), dtype=torch.float32, device="cuda"
+    ).contiguous()
+
+    ref = F.linear(mat_a, mat_b).to(torch.float32)
+
+    output = dsv3_router_gemm(mat_a, mat_b)
+
+    assert torch.allclose(
+        output, ref, rtol=1e-2, atol=1e-3
+    ), "Router GEMM output mismatch with torch.nn.functional.linear reference"
+
+
+if __name__ == "__main__":
+    pytest.main([__file__])