[Misc] Minor enhancement of benchmark_moe (#22068)

Signed-off-by: Jee Jee Li <pandaleefree@gmail.com>

benchmarks/kernels/benchmark_moe.py

@@ -22,6 +22,13 @@ from vllm.utils import FlexibleArgumentParser
 FP8_DTYPE = current_platform.fp8_dtype()
 
 
+def ensure_divisibility(numerator, denominator):
+    """Ensure that numerator is divisible by the denominator."""
+    assert numerator % denominator == 0, (
+        "intermediate_size {} is not divisible by tp {}.".format(numerator, denominator)
+    )
+
+
 class BenchmarkConfig(TypedDict):
     BLOCK_SIZE_M: int
     BLOCK_SIZE_N: int
@@ -603,7 +610,7 @@ def main(args: argparse.Namespace):
         topk = config.num_experts_per_tok
         intermediate_size = config.intermediate_size
         shard_intermediate_size = 2 * intermediate_size // args.tp_size
-
+    ensure_divisibility(intermediate_size, args.tp_size)
     hidden_size = config.hidden_size
     dtype = torch.float16 if current_platform.is_rocm() else config.torch_dtype
     use_fp8_w8a8 = args.dtype == "fp8_w8a8"