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vllm-omni/benchmarks/host_weight_runtime/safetensors_retention.py
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Python

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM-Omni project
"""Linux CPU diagnostic: repeated safetensors materialization versus view reuse."""
from __future__ import annotations
import argparse
import gc
import json
import os
import platform
import tempfile
import time
import weakref
from pathlib import Path
def positive_int(value: str) -> int:
parsed = int(value)
if parsed <= 0:
raise argparse.ArgumentTypeError("must be positive")
return parsed
def sample(phase: str, iterations: int, loop_seconds: float) -> dict[str, object]:
gc.collect()
counters = {}
for line in Path("/proc/self/smaps_rollup").read_text().splitlines():
fields = line.split()
if len(fields) == 3 and fields[2] == "kB":
counters[fields[0].removesuffix(":")] = int(fields[1]) * 1024
return {
"phase": phase,
"iterations": iterations,
"loop_seconds": loop_seconds,
"rss_bytes": counters["Rss"],
"private_bytes": counters["Private_Clean"] + counters["Private_Dirty"],
"anonymous_bytes": counters["Anonymous"],
"fd_count": len(tuple(Path("/proc/self/fd").iterdir())),
}
def main() -> None:
parser = argparse.ArgumentParser(description=__doc__)
parser.add_argument("--mode", choices=("get_tensor", "reuse"), required=True)
parser.add_argument(
"--tensor-elements", type=positive_int, default=64, help="Number of float32 elements in the synthetic tensor"
)
parser.add_argument("--iterations", type=positive_int, default=1_000_000)
parser.add_argument("--sample-every", type=positive_int, default=100_000)
parser.add_argument("--warmup", type=positive_int, default=1000)
args = parser.parse_args()
if not Path("/proc/self/smaps_rollup").is_file():
parser.error("requires Linux /proc/self/smaps_rollup")
preparation_start = time.monotonic()
import safetensors
import torch
from safetensors import safe_open
from safetensors.torch import save_file
torch.set_num_threads(1)
torch.set_num_interop_threads(1)
samples = [sample("before_file", 0, 0.0)]
with tempfile.TemporaryDirectory(prefix="safetensors-retention-") as directory:
path = Path(directory) / "synthetic.safetensors"
save_file({"weight": torch.arange(args.tensor_elements, dtype=torch.float32)}, str(path))
with safe_open(path, framework="pt", device="cpu") as reader:
cached = reader.get_tensor("weight")
assert torch.equal(cached, torch.arange(args.tensor_elements, dtype=torch.float32))
for _ in range(args.warmup):
tensor = reader.get_tensor("weight") if args.mode == "get_tensor" else cached
del tensor
samples.append(sample("baseline", 0, 0.0))
preparation_seconds = time.monotonic() - preparation_start
completed = 0
loop_seconds = 0.0
while completed < args.iterations:
count = min(args.sample_every, args.iterations - completed)
start = time.monotonic()
for _ in range(count):
tensor = reader.get_tensor("weight") if args.mode == "get_tensor" else cached
last_tensor = weakref.ref(tensor)
del tensor
loop_seconds += time.monotonic() - start
completed += count
snapshot = sample("loop", completed, loop_seconds)
snapshot["last_tensor_alive"] = last_tensor() is not None
if args.mode == "get_tensor":
assert last_tensor() is None, "diagnostic retained a transient tensor"
samples.append(snapshot)
del cached
del reader
samples.append(sample("closed", completed, loop_seconds))
assert last_tensor() is None, "last tensor survived reader/view teardown"
print(
json.dumps(
{
"schema_version": 1,
"arguments": vars(args),
"python": platform.python_version(),
"torch": torch.__version__,
"safetensors": safetensors.__version__,
"kernel": platform.release(),
"hostname": platform.node(),
"pid": os.getpid(),
"cpu_affinity": sorted(os.sched_getaffinity(0)),
"torch_threads": torch.get_num_threads(),
"pythonmalloc": os.environ.get("PYTHONMALLOC", "default"),
"preparation_seconds": preparation_seconds,
"samples": samples,
},
indent=2,
)
)
if __name__ == "__main__":
main()