| |
| """OPT_PLAN H7 (``BEVFUSION_HOST_MALLOC``): keep glibc from returning freed per-frame memory to the kernel. |
| |
| A frame allocates and frees tens of MB of short-lived arrays (the rulebook maps, the voxelizer's per-point arrays, |
| the decoded cloud). With glibc's defaults the freed top of the heap is trimmed (and large blocks are unmapped), so |
| the next frame takes those pages again as minor page faults: 15-17 MB (3.8-4.3 k faults, ~9 ms) per PandaSet |
| pre-processing call on this host (OPT_REPORT round 7). ``mallopt`` is process-wide, so this is applied once at model |
| load; it only changes when memory goes back to the kernel (the resident size stays at the per-frame peak). |
| |
| - ``default``: glibc as is; |
| - ``trim``: ``M_TRIM_THRESHOLD`` = 512 MiB (no top-of-heap trim below it) and ``M_MMAP_THRESHOLD`` = 32 MiB (glibc's |
| maximum). Setting either one freezes glibc's dynamic mmap threshold; frozen at its 128 KiB start (the model loads |
| this before its large arrays) every per-frame array would be a fresh mapping, which round 7 measured as slower |
| than the default, so the threshold is set explicitly; |
| - ``arena1``: ``trim`` + ``M_ARENA_MAX`` = 1 (worker threads allocate from the main heap too, so their frames reuse |
| the same pages; the threads then share the arena lock). |
| """ |
| from __future__ import annotations |
|
|
| import ctypes |
| import ctypes.util |
| from typing import Optional |
|
|
| __all__ = ["MODES", "apply"] |
|
|
| MODES = ("default", "trim", "arena1") |
| M_TRIM_THRESHOLD = -1 |
| M_ARENA_MAX = -8 |
| M_MMAP_THRESHOLD = -3 |
| MMAP_BYTES = 32 << 20 |
| TRIM_BYTES = 512 << 20 |
| _APPLIED: Optional[str] = None |
|
|
|
|
| def apply(mode: str) -> Optional[str]: |
| """Apply ``mode`` once per process (later calls with another mode are ignored); returns the applied mode or None |
| (``default``, or not glibc).""" |
| global _APPLIED |
| if mode not in MODES: |
| raise ValueError(f"HOST_MALLOC must be one of {MODES}") |
| if mode == "default" or _APPLIED is not None: |
| return _APPLIED |
| try: |
| libc = ctypes.CDLL(ctypes.util.find_library("c") or "libc.so.6") |
| mallopt = libc.mallopt |
| except (OSError, AttributeError): |
| return None |
| mallopt.argtypes = [ctypes.c_int, ctypes.c_int] |
| mallopt.restype = ctypes.c_int |
| ok = mallopt(M_MMAP_THRESHOLD, MMAP_BYTES) == 1 and mallopt(M_TRIM_THRESHOLD, TRIM_BYTES) == 1 |
| if ok and mode == "arena1": |
| ok = mallopt(M_ARENA_MAX, 1) == 1 |
| _APPLIED = mode if ok else None |
| return _APPLIED |
|
|
