perf(pathfinder): fast-path exact directory searches

benchmarks/cuda_pathfinder/.gitignore

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+results-*.json

benchmarks/cuda_pathfinder/AGENTS.md

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+# cuda.pathfinder benchmarks
+
+Read the README.md in this directory for benchmark scope and usage.
+
+Keep benchmark fixtures outside timed loops. Verify benchmark behavior against
+the source in `../../cuda_pathfinder` and preserve support for Linux and Windows.

benchmarks/cuda_pathfinder/README.md

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+# cuda.pathfinder benchmarks
+
+These benchmarks measure filesystem-discovery latency in `cuda.pathfinder`.
+They exercise the in-tree source package and do not require a GPU or CUDA
+Toolkit.
+
+The suite uses temporary directory trees prepared before timing starts. It has
+two levels of coverage:
+
+- `find_sub_dirs.*` isolates the underlying filesystem mechanism with realistic
+  one-root and three-root cases, plus wildcard and cache diagnostics.
+- `public_discovery.*` measures cold-cache calls through the public header,
+  binary, and static-library APIs. Fixtures use real NVIDIA wheel layouts such
+  as `nvidia/cuda_runtime/include` and `nvidia/cuda_nvcc/bin`.
+
+The public cold-cache benchmarks clear pathfinder's process-lifetime caches on
+each iteration. This intentionally models first use in a fresh process; the
+small cache-clear cost is included in the reported time. Three roots represent
+a virtual environment, user site-packages, and system site-packages, with the
+target in the last root to measure the complete search order.
+
+## Usage
+
+Requires pixi. The `source` environment installs `cuda-pathfinder` from this
+checkout and works on Linux and Windows.
+
+```bash
+# List benchmark IDs.
+pixi run -e source bench --list
+
+# Quick functional validation; timings are not meaningful.
+pixi run -e source bench-smoke-test
+
+# Run the full suite and write results-python.json.
+pixi run -e source bench
+
+# Reduce runtime while iterating.
+pixi run -e source bench --min-time 0.1
+```
+
+## Comparing changes
+
+Save results from the base revision and the modified checkout under distinct
+names, then use pyperf's statistical comparison:
+
+```bash
+pixi run -e source bench -o results-before.json
+pixi run -e source bench -o results-after.json
+pixi run -e source -- python -m pyperf compare_to \
+    results-before.json results-after.json --table
+```
+
+For stable results, minimize other system activity and use the same machine,
+Python version, and Pixi environment for both runs. See pyperf's system tuning
+guidance: https://pyperf.readthedocs.io/en/latest/system.html#system

benchmarks/cuda_pathfinder/benchmarks/bench_find_sub_dirs.py

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+# SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+import atexit
+import tempfile
+import time
+from pathlib import Path
+
+from cuda.pathfinder._utils.find_sub_dirs import find_sub_dirs, find_sub_dirs_cached, find_sub_dirs_no_cache
+
+_WILDCARD_CHILD_COUNT = 50
+_SUB_DIRS = ("nvidia", "cuda_runtime", "lib")
+_MISSING_SUB_DIRS = ("nvidia", "not_installed", "lib")
+
+_TEMP_DIR = tempfile.TemporaryDirectory()
+_ROOT = Path(_TEMP_DIR.name)
+_PARENTS: tuple[str, ...] = tuple(str(_ROOT / f"environment-{index}") for index in range(3))
+
+for parent in _PARENTS:
+    (Path(parent) / Path(*_SUB_DIRS)).mkdir(parents=True)
+
+_WILDCARD_PARENT = _ROOT / "wildcard-environment"
+for index in range(_WILDCARD_CHILD_COUNT):
+    (_WILDCARD_PARENT / "nvidia" / f"package-{index}" / "lib").mkdir(parents=True)
+
+_WILDCARD_PARENTS = (str(_WILDCARD_PARENT),)
+_WILDCARD_SUB_DIRS = ("nvidia", "*", "lib")
+
+find_sub_dirs_cached.cache_clear()
+find_sub_dirs(_PARENTS, _SUB_DIRS)
+
+
+def bench_exact_hit_1_parent(loops: int) -> float:
+    _fn = find_sub_dirs_no_cache
+    _parents = _PARENTS[:1]
+    _sub_dirs = _SUB_DIRS
+
+    t0 = time.perf_counter()
+    for _ in range(loops):
+        _fn(_parents, _sub_dirs)
+    return time.perf_counter() - t0
+
+
+def bench_exact_hit_3_parents(loops: int) -> float:
+    _fn = find_sub_dirs_no_cache
+    _parents = _PARENTS
+    _sub_dirs = _SUB_DIRS
+
+    t0 = time.perf_counter()
+    for _ in range(loops):
+        _fn(_parents, _sub_dirs)
+    return time.perf_counter() - t0
+
+
+def bench_exact_miss_3_parents(loops: int) -> float:
+    _fn = find_sub_dirs_no_cache
+    _parents = _PARENTS
+    _sub_dirs = _MISSING_SUB_DIRS
+
+    t0 = time.perf_counter()
+    for _ in range(loops):
+        _fn(_parents, _sub_dirs)
+    return time.perf_counter() - t0
+
+
+def bench_wildcard_hit_50_children(loops: int) -> float:
+    _fn = find_sub_dirs_no_cache
+    _parents = _WILDCARD_PARENTS
+    _sub_dirs = _WILDCARD_SUB_DIRS
+
+    t0 = time.perf_counter()
+    for _ in range(loops):
+        _fn(_parents, _sub_dirs)
+    return time.perf_counter() - t0
+
+
+def bench_cached_exact_hit(loops: int) -> float:
+    _fn = find_sub_dirs
+    _parents = _PARENTS
+    _sub_dirs = _SUB_DIRS
+    _fn(_parents, _sub_dirs)
+
+    t0 = time.perf_counter()
+    for _ in range(loops):
+        _fn(_parents, _sub_dirs)
+    return time.perf_counter() - t0
+
+
+atexit.register(_TEMP_DIR.cleanup)

benchmarks/cuda_pathfinder/benchmarks/bench_public_discovery.py

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+# SPDX-FileCopyrightText: Copyright (c) 2026 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
+#
+# SPDX-License-Identifier: Apache-2.0
+
+import atexit
+import os
+import site
+import tempfile
+import time
+from pathlib import Path
+
+from cuda.pathfinder import find_nvidia_binary_utility, find_nvidia_header_directory, locate_static_lib
+from cuda.pathfinder._headers.find_nvidia_headers import locate_nvidia_header_directory
+from cuda.pathfinder._utils.find_sub_dirs import find_sub_dirs_cached
+from cuda.pathfinder._utils.platform_aware import IS_WINDOWS
+
+_TEMP_DIR = tempfile.TemporaryDirectory()
+_ROOT = Path(_TEMP_DIR.name)
+_SITE_ROOTS = tuple(_ROOT / f"site-root-{index}" for index in range(3))
+for root in _SITE_ROOTS:
+    root.mkdir()
+
+_PACKAGE_ROOT = _SITE_ROOTS[-1] / "nvidia"
+_HEADER_DIR = _PACKAGE_ROOT / "cuda_runtime" / "include"
+_HEADER_DIR.mkdir(parents=True)
+(_HEADER_DIR / "cuda_runtime.h").touch()
+
+_BINARY_DIR = _PACKAGE_ROOT / "cuda_nvcc" / "bin"
+_BINARY_DIR.mkdir(parents=True)
+_BINARY_NAME = "nvdisasm.exe" if IS_WINDOWS else "nvdisasm"
+_BINARY_PATH = _BINARY_DIR / _BINARY_NAME
+_BINARY_PATH.touch()
+if not IS_WINDOWS:
+    _BINARY_PATH.chmod(0o755)
+
+_STATIC_LIB_DIR = _PACKAGE_ROOT / "cuda_runtime" / "lib"
+if IS_WINDOWS:
+    _STATIC_LIB_DIR /= "x64"
+_STATIC_LIB_DIR.mkdir(parents=True)
+_STATIC_LIB_NAME = "cudadevrt.lib" if IS_WINDOWS else "libcudadevrt.a"
+(_STATIC_LIB_DIR / _STATIC_LIB_NAME).touch()
+
+_ORIGINAL_GETSITEPACKAGES = site.getsitepackages
+_ORIGINAL_ENABLE_USER_SITE = site.ENABLE_USER_SITE
+_ACTIVE_SITE_ROOTS: tuple[Path, ...] = _SITE_ROOTS
+
+
+def _getsitepackages() -> list[str]:
+    return [str(root) for root in _ACTIVE_SITE_ROOTS]
+
+
+site.getsitepackages = _getsitepackages
+site.ENABLE_USER_SITE = False
+
+
+def _clear_discovery_caches() -> None:
+    find_sub_dirs_cached.cache_clear()
+    find_nvidia_binary_utility.cache_clear()
+    locate_nvidia_header_directory.cache_clear()
+
+
+def _cleanup() -> None:
+    site.getsitepackages = _ORIGINAL_GETSITEPACKAGES
+    site.ENABLE_USER_SITE = _ORIGINAL_ENABLE_USER_SITE
+    _TEMP_DIR.cleanup()
+
+
+def bench_header_cold_1_root(loops: int) -> float:
+    global _ACTIVE_SITE_ROOTS
+    _ACTIVE_SITE_ROOTS = _SITE_ROOTS[-1:]
+    _fn = find_nvidia_header_directory
+    _clear = _clear_discovery_caches
+
+    t0 = time.perf_counter()
+    for _ in range(loops):
+        _clear()
+        _fn("cudart")
+    return time.perf_counter() - t0
+
+
+def bench_header_cold_3_roots(loops: int) -> float:
+    global _ACTIVE_SITE_ROOTS
+    _ACTIVE_SITE_ROOTS = _SITE_ROOTS
+    _fn = find_nvidia_header_directory
+    _clear = _clear_discovery_caches
+
+    t0 = time.perf_counter()
+    for _ in range(loops):
+        _clear()
+        _fn("cudart")
+    return time.perf_counter() - t0
+
+
+def bench_binary_cold_1_root(loops: int) -> float:
+    global _ACTIVE_SITE_ROOTS
+    _ACTIVE_SITE_ROOTS = _SITE_ROOTS[-1:]
+    _fn = find_nvidia_binary_utility
+    _clear = _clear_discovery_caches
+
+    t0 = time.perf_counter()
+    for _ in range(loops):
+        _clear()
+        _fn("nvdisasm")
+    return time.perf_counter() - t0
+
+
+def bench_binary_cold_3_roots(loops: int) -> float:
+    global _ACTIVE_SITE_ROOTS
+    _ACTIVE_SITE_ROOTS = _SITE_ROOTS
+    _fn = find_nvidia_binary_utility
+    _clear = _clear_discovery_caches
+
+    t0 = time.perf_counter()
+    for _ in range(loops):
+        _clear()
+        _fn("nvdisasm")
+    return time.perf_counter() - t0
+
+
+def bench_static_lib_cold_3_roots(loops: int) -> float:
+    global _ACTIVE_SITE_ROOTS
+    _ACTIVE_SITE_ROOTS = _SITE_ROOTS
+    _fn = locate_static_lib
+    _clear = find_sub_dirs_cached.cache_clear
+
+    t0 = time.perf_counter()
+    for _ in range(loops):
+        _clear()
+        _fn("cudadevrt")
+    return time.perf_counter() - t0
+
+
+_clear_discovery_caches()
+assert find_nvidia_header_directory("cudart") == os.path.normpath(os.path.abspath(_HEADER_DIR))
+assert find_nvidia_binary_utility("nvdisasm") == os.path.abspath(_BINARY_PATH)
+assert locate_static_lib("cudadevrt").abs_path == os.path.join(os.path.abspath(_STATIC_LIB_DIR), _STATIC_LIB_NAME)
+_clear_discovery_caches()
+
+atexit.register(_cleanup)