[1/2] Speed up trtllm_mla attention backend (>10% e2e) (#10473)

sgl-kernel/python/sgl_kernel/elementwise.py

@@ -379,3 +379,15 @@ def concat_mla_k(
     k_rope: torch.Tensor,
 ):
     torch.ops.sgl_kernel.concat_mla_k(k, k_nope, k_rope)
+
+
+def concat_mla_absorb_q(
+    a: torch.Tensor,
+    b: torch.Tensor,
+):
+    *batch_dims, _ = a.shape
+    out = torch.empty(
+        (*batch_dims, a.shape[-1] + b.shape[-1]), device=a.device, dtype=a.dtype
+    )
+    torch.ops.sgl_kernel.concat_mla_absorb_q(a, b, out)
+    return out