Files
vllm/benchmarks/kv_cache/benchmark_block_pool.py
2025-07-18 12:34:40 -07:00

109 lines
3.1 KiB
Python

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
import gc
import time
from typing import Optional
from tabulate import tabulate
from vllm.utils import FlexibleArgumentParser
from vllm.v1.core.block_pool import BlockPool
class Metric:
def __init__(self) -> None:
self.cnt: int = 0
self.sum_v: int = 0
self.max_v: Optional[int] = None
def update(self, v: int) -> None:
self.cnt += 1
self.sum_v += v
if self.max_v is None:
self.max_v = v
else:
self.max_v = max(self.max_v, v)
def avg_v(self) -> float:
return self.sum_v * 1.0 / self.cnt
def main(args):
rows = []
for allocate_block in args.allocate_blocks:
# Enforce a GC collect ahead to minimize the impact among runs
gc.collect()
block_pool = BlockPool(num_gpu_blocks=args.num_gpu_blocks, enable_caching=True)
get_blocks_metric: Metric = Metric()
free_blocks_metric: Metric = Metric()
for _ in range(args.num_iteration):
t1 = time.monotonic_ns()
blocks = block_pool.get_new_blocks(allocate_block)
t2 = time.monotonic_ns()
block_pool.free_blocks(blocks)
t3 = time.monotonic_ns()
get_blocks_metric.update(t2 - t1)
free_blocks_metric.update(t3 - t2)
if get_blocks_metric.max_v is not None and free_blocks_metric.max_v is not None:
rows.append(
[
get_blocks_metric.cnt,
args.num_gpu_blocks,
allocate_block,
get_blocks_metric.avg_v() / 1000000,
get_blocks_metric.max_v / 1000000.0,
free_blocks_metric.avg_v() / 1000000,
free_blocks_metric.max_v / 1000000.0,
]
)
else:
print(
"No valid metrics found."
f" {get_blocks_metric.max_v=} {free_blocks_metric.max_v=}"
)
print(
tabulate(
rows,
headers=[
"Iterations",
"Total\nBlocks",
"Allocated\nBlocks",
"Get Blocks\nAvg (ms)",
"Get Blocks\nMax (ms)",
"Free Blocks\nAvg (ms)",
"Free Blocks\nMax (ms)",
],
tablefmt="grid",
floatfmt=".6f",
)
)
def invoke_main() -> None:
parser = FlexibleArgumentParser(
description="Benchmark the performance of BlockPool for KV Cache."
)
parser.add_argument("--num-gpu-blocks", type=int, default=100000)
parser.add_argument(
"--num-iteration",
type=int,
default=1000,
help="Number of iterations to run to stablize final data readings",
)
parser.add_argument(
"--allocate-blocks",
type=int,
nargs="*",
default=[10, 50, 100, 500, 1000],
help="Number of blocks to allocate",
)
args = parser.parse_args()
main(args)
if __name__ == "__main__":
invoke_main() # pragma: no cover