Files
nano-vllm/bench_vllm.py
2026-01-07 04:25:06 +08:00

94 lines
3.5 KiB
Python

import os
os.environ["VLLM_USE_V1"] = "1"
import time
from random import randint, seed
from vllm import LLM, SamplingParams
def bench_decode(llm, num_seqs, input_len, output_len):
"""Benchmark decode performance"""
seed(0)
prompt_token_ids = [[randint(0, 10000) for _ in range(input_len)] for _ in range(num_seqs)]
sampling_params = SamplingParams(temperature=0.6, ignore_eos=True, max_tokens=output_len)
prompt_token_ids = [dict(prompt_token_ids=p) for p in prompt_token_ids]
t = time.time()
llm.generate(prompt_token_ids, sampling_params, use_tqdm=False)
t = time.time() - t
# Calculate metrics
prefill_tokens = num_seqs * input_len
decode_tokens = num_seqs * output_len
decode_throughput = decode_tokens / t
print(f"[Decode] Input: {num_seqs}x{input_len}tok, Output: {decode_tokens}tok, Time: {t:.2f}s")
print(f" Throughput: {decode_throughput:.2f} tok/s (includes prefill overhead)")
def bench_prefill(llm, num_seqs, input_len):
"""Benchmark prefill performance"""
seed(0)
# Fixed length input, minimal output to focus on prefill
prompt_token_ids = [[randint(0, 10000) for _ in range(input_len)] for _ in range(num_seqs)]
sampling_params = SamplingParams(temperature=0.6, ignore_eos=True, max_tokens=1)
prompt_token_ids = [dict(prompt_token_ids=p) for p in prompt_token_ids]
t = time.time()
llm.generate(prompt_token_ids, sampling_params, use_tqdm=False)
t = time.time() - t
total_input_tokens = num_seqs * input_len
throughput = total_input_tokens / t
print(f"[Prefill] Input: {total_input_tokens}tok ({num_seqs}x{input_len}), Time: {t:.2f}s, Throughput: {throughput:.2f}tok/s")
def main():
import argparse
parser = argparse.ArgumentParser(description="Benchmark vLLM performance (for comparison)")
parser.add_argument("--input-len", type=int, default=None, help="Input length in tokens")
parser.add_argument("--output-len", type=int, default=64, help="Output length for decode benchmark (default: 64)")
parser.add_argument("--max-len", type=int, default=32*1024, help="Max model length (default: 32K)")
parser.add_argument("--bench-decode", action="store_true", help="Run decode benchmark (default: prefill only)")
parser.add_argument("--bench-all", action="store_true", help="Run both prefill and decode benchmarks")
args = parser.parse_args()
path = os.path.expanduser("~/models/Qwen3-4B-Instruct-2507/")
max_len = args.max_len
print(f"\n[vLLM] max_len={max_len}")
llm = LLM(
path,
enforce_eager=False,
max_model_len=max_len,
max_num_seqs=128,
gpu_memory_utilization=0.9,
)
# Warmup
print("\nWarming up...")
llm.generate([dict(prompt_token_ids=[0, 1, 2])], SamplingParams(max_tokens=10))
# Default input lengths
prefill_input_len = args.input_len if args.input_len else max_len - 1
decode_input_len = args.input_len if args.input_len else max_len - args.output_len
# Determine which benchmarks to run
run_prefill = not args.bench_decode or args.bench_all
run_decode = args.bench_decode or args.bench_all
if run_prefill:
print("\n" + "=" * 60)
print("Prefill Benchmark (vLLM)")
print("=" * 60)
bench_prefill(llm, num_seqs=1, input_len=prefill_input_len)
if run_decode:
print("\n" + "=" * 60)
print("Decode Benchmark (vLLM)")
print("=" * 60)
bench_decode(llm, num_seqs=1, input_len=decode_input_len, output_len=args.output_len)
if __name__ == "__main__":
main()