[cpu][bench] Add Fused MoE Micro Benchmark for CPU Backend (#32092)

Signed-off-by: andikarachman <andika.rachman.y@gmail.com>

benchmarks/kernels/cpu/benchmark_cpu_fused_moe.py

+# SPDX-License-Identifier: Apache-2.0
+# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
+
+import sys
+import time
+
+import numpy as np
+import torch
+
+from vllm.platforms import current_platform
+from vllm.utils.argparse_utils import FlexibleArgumentParser
+
+# Check if CPU MoE operations are available
+try:
+    from vllm._custom_ops import cpu_fused_moe, cpu_prepack_moe_weight
+except (ImportError, AttributeError) as e:
+    print("ERROR: CPU fused MoE operations are not available on this platform.")
+    print("This benchmark requires x86 CPU with proper vLLM CPU extensions compiled.")
+    print(
+        "The cpu_fused_moe kernel is typically available on Linux x86_64 "
+        "with AVX2/AVX512."
+    )
+    print(f"Import error: {e}")
+    sys.exit(1)
+
+# ISA selection following test_cpu_fused_moe.py pattern
+ISA_CHOICES = ["amx", "vec"] if torch._C._cpu._is_amx_tile_supported() else ["vec"]
+
+
+@torch.inference_mode()
+def main(
+    batch_size: int,
+    expert_num: int,
+    hidden_size: int,
+    intermediate_size: int,
+    topk_num: int,
+    use_bias: bool = False,
+    dtype: torch.dtype = torch.bfloat16,
+    activation: str = "silu",
+    isa: str = "vec",
+    seed: int = 0,
+    iters: int = 20,
+) -> None:
+    current_platform.seed_everything(seed)
+    # up_dim = 2 * intermediate_size for gate + up projection
+    up_dim = 2 * intermediate_size
+
+    input_tensor = torch.randn((batch_size, hidden_size), dtype=dtype) / (
+        0.5 * hidden_size**0.5
+    )
+
+    w13 = torch.randn((expert_num, up_dim, hidden_size), dtype=dtype) / (
+        0.5 * hidden_size**0.5
+    )
+    w2 = torch.randn((expert_num, hidden_size, intermediate_size), dtype=dtype) / (
+        0.5 * intermediate_size**0.5
+    )
+
+    w13_bias = None
+    w2_bias = None
+    if use_bias:
+        w13_bias = torch.randn((expert_num, up_dim), dtype=dtype) / (0.5 * up_dim**0.5)
+        w2_bias = torch.randn((expert_num, hidden_size), dtype=dtype) / (
+            0.5 * hidden_size**0.5
+        )
+
+    router_logits = torch.randn((batch_size, expert_num), dtype=dtype)
+    score = torch.softmax(router_logits, dim=-1, dtype=torch.float32)
+    topk_weights, topk_ids = torch.topk(score, topk_num)
+    topk_ids = topk_ids.to(torch.int32)
+
+    packed_w13 = cpu_prepack_moe_weight(w13, isa)
+    packed_w2 = cpu_prepack_moe_weight(w2, isa)
+
+    def run_benchmark(iters: int) -> list[float]:
+        times = []
+        for _ in range(iters):
+            start_time = time.perf_counter_ns()
+            _ = cpu_fused_moe(
+                input_tensor,
+                packed_w13,
+                packed_w2,
+                w13_bias,
+                w2_bias,
+                topk_weights,
+                topk_ids,
+                activation,
+                isa,
+            )
+            end_time = time.perf_counter_ns()
+            times.append((end_time - start_time) / 1e6)
+        return times
+
+    # warmup
+    run_benchmark(5)
+    # benchmark
+    times = run_benchmark(iters)
+
+    if not times:
+        print("No iterations to measure. Set --iters > 0.")
+        return
+
+    time_min = min(times)
+    time_max = max(times)
+    time_mean = np.mean(times)
+    time_std = np.std(times)
+
+    print("\tmin (ms) = ", time_min)
+    print("\tmax (ms) = ", time_max)
+    print("\tmean (ms) = ", time_mean)
+    print("\tstd = ", time_std)
+    print("\tmedian (ms) = ", np.median(times))
+
+    # Calculate throughput metrics
+    # FLOPs estimation: 2 * batch * topk * (hidden * up_dim + intermediate * hidden)
+    flops_per_token = (
+        2 * topk_num * (hidden_size * up_dim + intermediate_size * hidden_size)
+    )
+    total_flops = batch_size * flops_per_token
+    tflops = total_flops / (time_mean * 1e-3) / 1e12
+    print(f"\tthroughput (TFLOP/s) = {tflops:.4f}")
+
+
+if __name__ == "__main__":
+    parser = FlexibleArgumentParser(description="Benchmark the CPU fused MoE kernel.")
+    parser.add_argument("--batch-size", type=int, default=64)
+    parser.add_argument("--expert-num", type=int, default=8)
+    parser.add_argument("--hidden-size", type=int, default=2880)
+    parser.add_argument("--intermediate-size", type=int, default=2880)
+    parser.add_argument(
+        "--topk-num",
+        type=int,
+        default=None,
+        help="Number of experts to route each token to (default: expert_num // 2)",
+    )
+    parser.add_argument("--use-bias", action="store_true")
+    parser.add_argument(
+        "--activation",
+        type=str,
+        choices=["silu", "swigluoai"],
+        default="silu",
+        help="Activation function",
+    )
+    parser.add_argument(
+        "--isa",
+        type=str,
+        choices=ISA_CHOICES,
+        default=ISA_CHOICES[0],
+        help=f"ISA to use (available: {ISA_CHOICES})",
+    )
+    parser.add_argument("--seed", type=int, default=0)
+    parser.add_argument("--iters", type=int, default=20)
+
+    args = parser.parse_args()
+
+    # Default topk_num to expert_num // 2, minimum 1
+    topk_num = (
+        args.topk_num if args.topk_num is not None else max(args.expert_num // 2, 1)
+    )
+
+    print(args)
+
+    main(
+        batch_size=args.batch_size,
+        expert_num=args.expert_num,
+        hidden_size=args.hidden_size,
+        intermediate_size=args.intermediate_size,
+        topk_num=topk_num,
+        use_bias=args.use_bias,
+        dtype=torch.bfloat16,  # Following test_cpu_fused_moe.py
+        activation=args.activation,
+        isa=args.isa,
+        seed=args.seed,
+        iters=args.iters,
+    )