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chore: import upstream snapshot with attribution
2026-07-13 12:55:37 +08:00

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Python

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
"""Benchmark and regression-test pinned (page-locked) CPU memory for vLLM.
Verifies that enabling pinned memory does not regress throughput or latency
compared to unpinned memory. Each condition runs in an isolated ``spawn``
subprocess so both start from a cold CUDA context, giving an unbiased
comparison.
Usage
-----
Run all tests with the default model::
python benchmarks/benchmark_pin_memory.py -v
Override the model and optional max-model-len::
python benchmarks/benchmark_pin_memory.py --model unsloth/Qwen3-1.7B -v
python benchmarks/benchmark_pin_memory.py --model unsloth/Qwen3-1.7B \
--max-model-len 8192 -v
Run only throughput or latency tests::
python benchmarks/benchmark_pin_memory.py -v -k test_throughput
python benchmarks/benchmark_pin_memory.py -v -k test_latency
Run only the v1 or v2 runner variant::
python benchmarks/benchmark_pin_memory.py -v -k v1
python benchmarks/benchmark_pin_memory.py -v -k v2
Note: on WSL2, v1 runner tests are skipped because pin memory is not available
for the v1 runner without cpu_offload_gb. Run on other platforms to exercise v1.
"""
import argparse
import json
import multiprocessing
import sys
import tempfile
import pytest
# Allow up to 2% degradation. Both benchmark runs start from an identical
# cold CUDA context (separate spawn subprocesses), so the measured difference
# reflects the genuine pin_memory overhead rather than cold/warm ordering bias.
_THROUGHPUT_TOLERANCE = 0.98
_THROUGHPUT_NUM_REQUESTS = 200
_THROUGHPUT_INPUT_LEN = 128
_THROUGHPUT_OUTPUT_LEN = 512
_THROUGHPUT_MAX_NUM_SEQS = 128
# Latency benchmark constants — match latency.py defaults.
_LATENCY_TOLERANCE = 1.02 # Allow up to 2% latency regression.
_LATENCY_BATCH_SIZE = 64
_LATENCY_INPUT_LEN = 32
_LATENCY_OUTPUT_LEN = 128
_LATENCY_WARMUP_ITERS = 5
_LATENCY_BENCH_ITERS = 15
_DEFAULT_MODEL = "unsloth/Qwen3-1.7B"
_DEFAULT_MAX_MODEL_LEN = 16384
def _benchmark_args() -> argparse.Namespace:
parser = argparse.ArgumentParser(add_help=False)
parser.add_argument("--model", default=_DEFAULT_MODEL)
parser.add_argument("--max-model-len", type=int, default=_DEFAULT_MAX_MODEL_LEN)
args, _ = parser.parse_known_args()
return args
@pytest.fixture
def model() -> str:
return _benchmark_args().model
@pytest.fixture
def max_model_len() -> int:
return _benchmark_args().max_model_len
def _skip_if_pin_memory_not_available(engine_args_kwargs: dict) -> None:
"""Skip the current pytest test if pin_memory is unavailable for this config."""
import vllm.utils.platform_utils as pu
from vllm.config import set_current_vllm_config
from vllm.engine.arg_utils import EngineArgs
vllm_config = EngineArgs(**engine_args_kwargs).create_engine_config()
with set_current_vllm_config(vllm_config):
pu.is_pin_memory_available.cache_clear()
if not pu.is_pin_memory_available():
import os
runner = "v2" if os.environ.get("VLLM_USE_V2_MODEL_RUNNER") == "1" else "v1"
model = engine_args_kwargs.get("model", "unknown")
print(
f"\033[33mSKIP: pin_memory not available for "
f"{runner} runner, model={model}\033[0m"
)
pytest.skip("pin_memory not available for this configuration")
def _throughput_worker(
pin: bool,
engine_args_kwargs: dict,
q: "multiprocessing.Queue[float]",
v2_mode: bool = False,
) -> None:
"""Run throughput benchmark in a fresh spawn subprocess.
Delegates to vllm/benchmarks/throughput.py main() using the random dataset,
so the methodology matches the official benchmark. Results are written to a
temp JSON file and forwarded through the queue as tokens/s.
v2_mode: when True, monkeypatches is_uva_available() to always return True
so the v2 model runner's UVA buffers remain functional even when pin=False.
This isolates the non-UVA pin_memory paths in v2.
"""
import vllm.utils.platform_utils as pu
from vllm.platforms import current_platform
pu.is_pin_memory_available.cache_clear()
pu.is_uva_available.cache_clear()
type(current_platform).is_pin_memory_available = classmethod(lambda cls: pin)
if v2_mode:
pu.is_uva_available = lambda: True
from vllm.benchmarks.throughput import add_cli_args
from vllm.benchmarks.throughput import main as throughput_main
parser = argparse.ArgumentParser()
add_cli_args(parser)
args = parser.parse_args([])
for key, val in engine_args_kwargs.items():
setattr(args, key, val)
args.max_num_seqs = _THROUGHPUT_MAX_NUM_SEQS
args.dataset_name = "random"
args.input_len = _THROUGHPUT_INPUT_LEN
args.output_len = _THROUGHPUT_OUTPUT_LEN
# Nullify defaults that conflict with explicit input/output_len.
args.random_input_len = None
args.random_output_len = None
args.random_prefix_len = None
args.num_prompts = _THROUGHPUT_NUM_REQUESTS
args.seed = 0
args.disable_detokenize = True
with tempfile.NamedTemporaryFile(mode="w", suffix=".json", delete=False) as f:
tmp_path = f.name
args.output_json = tmp_path
throughput_main(args)
with open(tmp_path) as f:
results = json.load(f)
q.put(results["tokens_per_second"])
def _run_throughput_benchmark(
pin: bool,
engine_args_kwargs: dict,
v2_mode: bool = False,
) -> float:
ctx = multiprocessing.get_context("spawn")
q = ctx.Queue()
p = ctx.Process(
target=_throughput_worker,
args=(pin, engine_args_kwargs, q, v2_mode),
)
p.start()
p.join()
if p.exitcode != 0:
raise RuntimeError(
f"Throughput benchmark subprocess (pin={pin}) exited with code {p.exitcode}"
)
return q.get()
def _latency_worker(
pin: bool,
engine_args_kwargs: dict,
q: "multiprocessing.Queue[dict]",
v2_mode: bool = False,
) -> None:
"""Run latency benchmark in a fresh spawn subprocess.
Follows latency.py methodology: fixed batch of dummy token IDs, warmup
iterations to reach steady state, then timed iterations reduced to avg
and percentiles. Results are written to a temp JSON file by latency_main
and forwarded through the queue.
"""
import vllm.utils.platform_utils as pu
from vllm.platforms import current_platform
pu.is_pin_memory_available.cache_clear()
pu.is_uva_available.cache_clear()
type(current_platform).is_pin_memory_available = classmethod(lambda cls: pin)
if v2_mode:
pu.is_uva_available = lambda: True
from vllm.benchmarks.latency import add_cli_args
from vllm.benchmarks.latency import main as latency_main
parser = argparse.ArgumentParser()
add_cli_args(parser)
args = parser.parse_args([])
for key, val in engine_args_kwargs.items():
setattr(args, key, val)
args.input_len = _LATENCY_INPUT_LEN
args.output_len = _LATENCY_OUTPUT_LEN
args.batch_size = _LATENCY_BATCH_SIZE
args.num_iters_warmup = _LATENCY_WARMUP_ITERS
args.num_iters = _LATENCY_BENCH_ITERS
args.profile = False
args.disable_detokenize = True
with tempfile.NamedTemporaryFile(mode="w", suffix=".json", delete=False) as f:
tmp_path = f.name
args.output_json = tmp_path
latency_main(args)
with open(tmp_path) as f:
results = json.load(f)
q.put(results)
def _run_latency_benchmark(
pin: bool,
engine_args_kwargs: dict,
v2_mode: bool = False,
) -> dict:
ctx = multiprocessing.get_context("spawn")
q = ctx.Queue()
p = ctx.Process(
target=_latency_worker,
args=(pin, engine_args_kwargs, q, v2_mode),
)
p.start()
p.join()
if p.exitcode != 0:
raise RuntimeError(
f"Latency benchmark subprocess (pin={pin}) exited with code {p.exitcode}"
)
return q.get()
@pytest.mark.parametrize(
"test_v2_runner",
[
pytest.param(False, id="v1"),
pytest.param(True, id="v2"),
],
)
class TestPinnedMemory:
"""Verify pinned memory yields >= throughput vs unpinned via real vLLM inference."""
def test_throughput(self, monkeypatch, test_v2_runner, model, max_model_len):
"""Benchmark throughput with pin_memory forced on then off.
Delegates to vllm/benchmarks/throughput.py main() with the random
dataset. Each condition runs in an isolated spawn subprocess so both
start from a cold CUDA context, giving an unbiased comparison.
"""
monkeypatch.setenv("VLLM_ENABLE_V1_MULTIPROCESSING", "0")
monkeypatch.setenv("VLLM_USE_V2_MODEL_RUNNER", "1" if test_v2_runner else "0")
engine_args_kwargs = dict(
model=model,
gpu_memory_utilization=0.88,
max_model_len=max_model_len,
enable_prefix_caching=False,
)
_skip_if_pin_memory_not_available(engine_args_kwargs)
unpinned_tps = _run_throughput_benchmark(
False, engine_args_kwargs, v2_mode=test_v2_runner
)
pinned_tps = _run_throughput_benchmark(
True, engine_args_kwargs, v2_mode=test_v2_runner
)
pct_diff = (pinned_tps - unpinned_tps) / unpinned_tps * 100
runner = "v2" if test_v2_runner else "v1"
print(
f"\n=== Throughput results ({runner} runner, {model}) ==="
f"\npin_memory=True: {pinned_tps:.1f} tok/s"
f"\npin_memory=False: {unpinned_tps:.1f} tok/s"
f"\nDifference: {pct_diff:+.1f}% (pinned vs unpinned)"
)
assert pinned_tps >= unpinned_tps * _THROUGHPUT_TOLERANCE, (
f"Pinned throughput ({pinned_tps:.1f} tok/s) fell more than "
f"{(1.0 - _THROUGHPUT_TOLERANCE) * 100:.1f}% below "
f"unpinned ({unpinned_tps:.1f} tok/s)."
)
def test_latency(self, monkeypatch, test_v2_runner, model, max_model_len):
"""Benchmark per-batch latency with pin_memory forced on then off.
Follows vllm/benchmarks/latency.py: fixed dummy-token batch, warmup
iterations to reach steady state, then timed iterations reduced to avg
and percentiles. Subprocesses run serially so each gets a cold CUDA
context without GPU memory pressure from the other run.
"""
monkeypatch.setenv("VLLM_ENABLE_V1_MULTIPROCESSING", "0")
monkeypatch.setenv("VLLM_USE_V2_MODEL_RUNNER", "1" if test_v2_runner else "0")
engine_args_kwargs = dict(
model=model,
gpu_memory_utilization=0.88,
max_model_len=max_model_len,
enable_prefix_caching=False,
)
_skip_if_pin_memory_not_available(engine_args_kwargs)
unpinned = _run_latency_benchmark(
False, engine_args_kwargs, v2_mode=test_v2_runner
)
pinned = _run_latency_benchmark(
True, engine_args_kwargs, v2_mode=test_v2_runner
)
pct_diff = (
(pinned["avg_latency"] - unpinned["avg_latency"])
/ unpinned["avg_latency"]
* 100
)
runner = "v2" if test_v2_runner else "v1"
print(
f"\n=== Latency results ({runner} runner, {model}) ==="
f"\npin_memory=True: avg={pinned['avg_latency']:.3f}s"
f" p50={pinned['percentiles']['50']:.3f}s"
f" p99={pinned['percentiles']['99']:.3f}s"
f"\npin_memory=False: avg={unpinned['avg_latency']:.3f}s"
f" p50={unpinned['percentiles']['50']:.3f}s"
f" p99={unpinned['percentiles']['99']:.3f}s"
f"\nDifference: {pct_diff:+.1f}% (pinned vs unpinned)"
)
assert pinned["avg_latency"] <= unpinned["avg_latency"] * _LATENCY_TOLERANCE, (
f"Pinned avg latency ({pinned['avg_latency']:.3f}s) exceeded "
f"unpinned ({unpinned['avg_latency']:.3f}s) by more than "
f"{(_LATENCY_TOLERANCE - 1.0) * 100:.1f}%."
)
if __name__ == "__main__":
_parser = argparse.ArgumentParser(add_help=False)
_parser.add_argument("--model", default=_DEFAULT_MODEL)
_parser.add_argument("--max-model-len", type=int, default=_DEFAULT_MAX_MODEL_LEN)
_, _remaining = _parser.parse_known_args()
sys.exit(pytest.main([__file__] + _remaining))