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Add vLLM-metax vllm metax cmake presets jobs override #305

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a40b79e
Allow CMake preset parallelism overrides
ghangz Jun 30, 2026
bd02403
Guard preset job calculation for zero CPUs
ghangz Jul 1, 2026
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44 changes: 44 additions & 0 deletions tests/tools/test_generate_cmake_presets_jobs.py
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Original file line number Diff line number Diff line change
@@ -0,0 +1,44 @@
import json

import tools.generate_cmake_presets as presets


def test_generate_presets_accepts_parallelism_overrides(monkeypatch, tmp_path):
output_path = tmp_path / "CMakeUserPresets.json"
nvcc_path = tmp_path / "bin" / "nvcc"
nvcc_path.parent.mkdir()
nvcc_path.write_text("", encoding="utf-8")

monkeypatch.setattr(presets, "CUDA_HOME", str(tmp_path))
monkeypatch.setattr(presets, "which", lambda name: None)
monkeypatch.setattr(presets, "get_cpu_cores", lambda: 64)

presets.generate_presets(
output_path=str(output_path),
force_overwrite=True,
cmake_jobs=3,
nvcc_threads=2,
)

data = json.loads(output_path.read_text())
cache = data["configurePresets"][0]["cacheVariables"]
assert cache["NVCC_THREADS"] == "2"
assert data["buildPresets"][0]["jobs"] == 3


def test_generate_presets_handles_zero_cpu_count(monkeypatch, tmp_path):
output_path = tmp_path / "CMakeUserPresets.json"
nvcc_path = tmp_path / "bin" / "nvcc"
nvcc_path.parent.mkdir()
nvcc_path.write_text("", encoding="utf-8")

monkeypatch.setattr(presets, "CUDA_HOME", str(tmp_path))
monkeypatch.setattr(presets, "which", lambda name: None)
monkeypatch.setattr(presets, "get_cpu_cores", lambda: 0)

presets.generate_presets(output_path=str(output_path), force_overwrite=True)

data = json.loads(output_path.read_text())
cache = data["configurePresets"][0]["cacheVariables"]
assert cache["NVCC_THREADS"] == "1"
assert data["buildPresets"][0]["jobs"] == 1
42 changes: 37 additions & 5 deletions tools/generate_cmake_presets.py
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Original file line number Diff line number Diff line change
Expand Up @@ -27,7 +27,19 @@ def get_cpu_cores():
return multiprocessing.cpu_count()


def generate_presets(output_path="CMakeUserPresets.json", force_overwrite=False):
def _detect_cpu_cores():
cpu_cores = get_cpu_cores()
if not cpu_cores or cpu_cores < 1:
return 1
return cpu_cores


def generate_presets(
output_path="CMakeUserPresets.json",
force_overwrite=False,
cmake_jobs=None,
nvcc_threads=None,
):
"""Generates the CMakeUserPresets.json file."""

print("Attempting to detect your system configuration...")
Expand Down Expand Up @@ -73,9 +85,15 @@ def generate_presets(output_path="CMakeUserPresets.json", force_overwrite=False)
print(f"Using Python executable: {python_executable}")

# Get CPU cores
cpu_cores = get_cpu_cores()
nvcc_threads = min(4, cpu_cores)
cmake_jobs = max(1, cpu_cores // nvcc_threads)
cpu_cores = _detect_cpu_cores()
if nvcc_threads is None:
nvcc_threads = min(4, cpu_cores)
elif nvcc_threads < 1:
raise ValueError("nvcc_threads must be at least 1")
if cmake_jobs is None:
cmake_jobs = max(1, cpu_cores // nvcc_threads)
elif cmake_jobs < 1:
raise ValueError("cmake_jobs must be at least 1")
Comment on lines +89 to +96

@gemini-code-assist gemini-code-assist Bot Jul 1, 2026

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high

If get_cpu_cores() returns None (which multiprocessing.cpu_count() can do on some platforms) or returns 0 (which can happen in certain containerized or restricted environments), the current logic will raise a TypeError or a ZeroDivisionError.

Specifically, if cpu_cores is 0, nvcc_threads is set to 0 via min(4, 0). Then, calculating cmake_jobs using cpu_cores // nvcc_threads results in 0 // 0, which raises a ZeroDivisionError.

We can make this logic robust against both None and 0 values by defaulting cpu_cores to at least 1 and ensuring nvcc_threads is at least 1.

Suggested change
if nvcc_threads is None:
nvcc_threads = min(4, cpu_cores)
elif nvcc_threads < 1:
raise ValueError("nvcc_threads must be at least 1")
if cmake_jobs is None:
cmake_jobs = max(1, cpu_cores // nvcc_threads)
elif cmake_jobs < 1:
raise ValueError("cmake_jobs must be at least 1")
if nvcc_threads is None:
nvcc_threads = max(1, min(4, cpu_cores or 1))
elif nvcc_threads < 1:
raise ValueError("nvcc_threads must be at least 1")
if cmake_jobs is None:
cmake_jobs = max(1, (cpu_cores or 1) // nvcc_threads)
elif cmake_jobs < 1:
raise ValueError("cmake_jobs must be at least 1")

print(
f"Detected {cpu_cores} CPU cores. "
f"Setting NVCC_THREADS={nvcc_threads} and CMake jobs={cmake_jobs}."
Expand Down Expand Up @@ -171,11 +189,25 @@ def generate_presets(output_path="CMakeUserPresets.json", force_overwrite=False)

if __name__ == "__main__":
parser = argparse.ArgumentParser()
parser.add_argument(
"--cmake-jobs",
type=int,
help="Override build preset jobs instead of deriving it from CPU cores",
)
parser.add_argument(
"--nvcc-threads",
type=int,
help="Override NVCC_THREADS instead of deriving it from CPU cores",
)
parser.add_argument(
"--force-overwrite",
action="store_true",
help="Force overwrite existing CMakeUserPresets.json without prompting",
)

args = parser.parse_args()
generate_presets(force_overwrite=args.force_overwrite)
generate_presets(
force_overwrite=args.force_overwrite,
cmake_jobs=args.cmake_jobs,
nvcc_threads=args.nvcc_threads,
)