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Merge pull request #332 from woolcoxm/fix/auto-tier-single-core

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resource_plan: fix --auto-tier pinning decode to one core (#325)
This commit is contained in:
Vincenzo Fornaro
2026-07-20 17:19:50 +02:00
committed by GitHub
parent af23f314fd 171aa69fcb
commit 0337697023
2 changed files with 243 additions and 23 deletions
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c/resource_plan.py
+93 -16
View File
@@ -166,14 +166,33 @@ def discover_gpus():
return devices
def _physical_cores_warn(message):
"""Visibility for a mis-detected core count: a silent "1" here becomes
OMP_NUM_THREADS=1 and pins the whole run to a single core (#325). Emit on
stderr so it surfaces in the [PLAN]/[OMP] stream without being swallowed."""
print(f"[plan] warning: {message}", file=sys.stderr)
def physical_cpu_count():
"""Number of physical CPU cores (not SMT siblings).
Per-expert matmul regions are tiny and back-to-back; two SMT siblings share
one AVX-512 unit and contend, so logical (SMT) counts over-subscribe and
hurt throughput. We want true physical cores. A silent 1 here propagates to
OMP_NUM_THREADS=1 and pins the run to one core (#325), so every fallback
must be visible, never just ``or 1``.
"""
if sys.platform == "win32":
# os.cpu_count() conta i processori logici (SMT): 2 thread/core saturano
# le unita' AVX-512 e peggiorano il matmul. Contiamo i core fisici veri
# con GetLogicalProcessorInformationEx(RelationProcessorCore).
# Contiamo i core fisici veri con GetLogicalProcessorInformationEx
# (RelationProcessorCore). Le firme vanno dichiarate: su Python a 64 bit
# una WinAPI non dichiarata ritorna c_int (32 bit) e riceve i puntatori
# come c_int di default, quindi il probe puo' fallire silenziosamente.
try:
import ctypes
k32 = ctypes.windll.kernel32
k32.GetLogicalProcessorInformationEx.argtypes = [
ctypes.c_uint, ctypes.c_void_p, ctypes.POINTER(ctypes.c_ulong)]
k32.GetLogicalProcessorInformationEx.restype = ctypes.c_int
need = ctypes.c_ulong(0)
k32.GetLogicalProcessorInformationEx(0, None, ctypes.byref(need))
buf = (ctypes.c_char * need.value)()
@@ -189,18 +208,69 @@ def physical_cpu_count():
off += size
if cores:
return cores
except (OSError, ValueError, AttributeError):
pass
_physical_cores_warn("GetLogicalProcessorInformationEx returned no cores")
except (OSError, ValueError, AttributeError) as error:
_physical_cores_warn(f"Windows core probe failed: {error}")
try:
# Ask lscpu for exactly core,socket and dedupe on (core, socket).
# Counting un-deduplicated rows would return logical threads (SMT),
# which was the original over-subscription bug. Empty fields ("-")
# mark an offline core/socket and fail int() -> skipped.
#
# Column layout robustness: `lscpu -p=<list>` emits *exactly* the
# requested columns (no CPU prefix), while bare `lscpu -p` prepends
# CPU. We requested two columns, but take the LAST TWO fields so the
# parser stays correct whether or not a CPU column is present
# (JustVugg review: the previous fields[1]/fields[2] indexing assumed
# a 3-column layout and regressed 2-column output to the logical
# count -- the opposite of the fix).
result = subprocess.run(["lscpu", "-p=core,socket"], text=True,
capture_output=True, check=True, timeout=5)
cores = {tuple(map(int, line.split(","))) for line in result.stdout.splitlines()
if line and not line.startswith("#")}
cores = set()
for line in result.stdout.splitlines():
if not line or line.startswith("#"):
continue
fields = line.split(",")
if len(fields) < 2:
continue
try:
core, socket = int(fields[-2]), int(fields[-1])
except ValueError:
continue # "-" for an offline core/socket
cores.add((core, socket))
if cores:
return len(cores)
except (OSError, ValueError, subprocess.SubprocessError):
pass
return os.cpu_count() or 1
except (OSError, ValueError, subprocess.SubprocessError) as error:
_physical_cores_warn(f"lscpu core probe failed: {error}")
logical = os.cpu_count()
if not logical:
_physical_cores_warn(
"could not detect any CPU cores; falling back to 1. "
"Set OMP_NUM_THREADS manually to fix single-core decode (#325).")
return 1
_physical_cores_warn(
f"physical-core probes unavailable; using {logical} logical CPUs "
f"(SMT may over-subscribe). Set OMP_NUM_THREADS to physical cores if slow.")
return logical
def _resolve_physical_cores(physical_cpus):
"""Coerce the build_plan() physical-core argument to a sane positive int.
A None/0/None-ish value reaching here means physical_cpu_count() already
warned; clamp to 1 (so the engine always gets a positive team size) but keep
that clamp visible rather than silently masking it as the old ``max(1, int())``
did (#325)."""
try:
count = int(physical_cpus or 0)
except (TypeError, ValueError):
count = 0
if count < 1:
_physical_cores_warn(
"physical core count resolved to 0; defaulting to 1. "
"Set OMP_NUM_THREADS to fix single-core decode (#325).")
return 1
return count
def cpu_socket_count():
@@ -366,7 +436,7 @@ def build_plan(model, ram_gb=0, context=4096, gpu_indices=None, vram_gb=0,
"policy": {"name": policy, **POLICIES[policy],
"quality_preserving": policy != "experimental-fast"},
"model": {key: value for key, value in info.items() if key != "config"},
"cpu": {"physical_cores": max(1, int(physical_cpus)),
"cpu": {"physical_cores": _resolve_physical_cores(physical_cpus),
"sockets": max(1, int(cpu_sockets)),
"thread_policy": "physical-cores"},
"tiers": {
@@ -398,11 +468,18 @@ def environment_for_plan(plan, env=None, cuda_enabled=True):
result = dict(env or {})
result.setdefault("COLI_POLICY", plan["policy"]["name"])
result.setdefault("OMP_NUM_THREADS", str(plan["cpu"]["physical_cores"]))
if sys.platform != "win32":
# la libgomp di MinGW non supporta l'affinity su Windows
# ("Affinity not supported on this configuration"): non impostarle li'.
result.setdefault("OMP_PROC_BIND", "spread")
result.setdefault("OMP_PLACES", "cores")
# NOTE: we intentionally do NOT set OMP_PROC_BIND / OMP_PLACES here.
# The engine's own hot-thread tuning (glm.c main(), the COLI_OMP_TUNED
# self-exec) sets OMP_PROC_BIND=close with overwrite=0 -- it prefers
# packing the team onto adjacent cores for the tiny back-to-back per-expert
# matmuls. Pre-setting OMP_PROC_BIND=spread here ran first and won (the
# engine's overwrite=0 setenv could not override an already-set var), and
# spread + OMP_PLACES=cores collapsed the team to one CPU on some libgomp /
# multi-socket topologies (#325: --auto-tier pinned decode to 1 core on a
# 64-core box even with OMP_NUM_THREADS=64). Leaving affinity to the engine
# makes --auto-tier match the plain (working) path. A user who wants a
# specific policy can still set OMP_PROC_BIND/OMP_PLACES in the environment
# themselves -- setdefault above only covers OMP_NUM_THREADS.
tune = plan.get("tune", {})
for key, entry in tune.items():
if key.startswith("_"):
c/tests/test_resource_plan.py
+150 -7
View File
@@ -5,6 +5,7 @@ import sys
import tempfile
import unittest
from pathlib import Path
from unittest import mock
from resource_plan import (
GB,
@@ -14,6 +15,7 @@ from resource_plan import (
environment_for_plan,
format_plan,
memory_available,
physical_cpu_count,
)
@@ -87,6 +89,79 @@ class ResourcePlanTest(unittest.TestCase):
self.assertIn("clamped", plan["warnings"][0])
self.assertIn("0:test-gpu", format_plan(plan))
def test_auto_tier_thread_count_uses_physical_cores(self):
# End-to-end for #325: build_plan + environment_for_plan must export the
# physical (not logical SMT) core count as OMP_NUM_THREADS. The original
# suite passed physical_cpus=24 explicitly, so it never exercised the
# real physical_cpu_count() probe whose single-core failure pinned decode.
def lscpu(stdout):
return subprocess.CompletedProcess(args=[], returncode=0,
stdout=stdout, stderr="")
# 1 socket, 12 cores, 2 SMT siblings -> 24 threads, 12 physical cores.
# The parser must return 12 physical cores under BOTH lscpu layouts:
# - 2-col: `lscpu -p=core,socket` emits exactly [core,socket] (this is
# what the probe actually requests; the previous fields[1]/[2]
# indexing skipped every line here and fell through to the
# logical count -> the regression JustVugg caught).
# - 3-col: bare `lscpu -p` prepends a CPU column -> [cpu,core,socket].
# Taking the last two fields is correct in both cases.
layouts = {
"2-col (-p=core,socket)": (
"# core,socket\n" +
"\n".join(f"{core},0" for core in range(12) for _ in range(2))),
"3-col (bare -p, CPU prefix)": (
"# CPU,Core,Socket\n" +
"\n".join(f"{cpu},{core},0" for core in range(12) for cpu in range(2))),
}
for label, blob in layouts.items():
with mock.patch("resource_plan.subprocess.run",
return_value=lscpu(blob)), \
mock.patch.object(sys, "platform", "linux"):
plan = build_plan(self.model, available_memory=16 * GB,
available_disk=1, gpus=[])
env = environment_for_plan(plan)
self.assertEqual(plan["cpu"]["physical_cores"], 12, label)
self.assertEqual(env["OMP_NUM_THREADS"], "12", label)
def test_plan_does_not_set_omp_affinity_vars(self):
# The real #325 regression: --auto-tier set OMP_PROC_BIND=spread +
# OMP_PLACES=cores, which ran before the engine's overwrite=0 setenv and
# so won, collapsing the OpenMP team to one CPU on the reporter's 64-core
# Linux box even though OMP_NUM_THREADS was correct. The plan must leave
# affinity to the engine's own hot-thread tuning (which prefers 'close').
plan = build_plan(self.model, available_memory=16 * GB,
available_disk=1, gpus=[], physical_cpus=64)
env = environment_for_plan(plan)
self.assertEqual(env["OMP_NUM_THREADS"], "64")
self.assertNotIn("OMP_PROC_BIND", env)
self.assertNotIn("OMP_PLACES", env)
def test_plan_conserves_budget_and_experts_above_256gb(self):
# Regression for #325's reporter: a 512 GB machine loading the whole
# model into RAM. Verify the budget math stays exact at large RAM sizes
# (no integer truncation, no over-allocation, no experts lost between
# tiers). Checked at 256/512/800 GB to bracket the reporter's box.
for ram_gb in (256, 512, 800):
plan = build_plan(self.model, ram_gb=ram_gb, available_disk=1,
gpus=[], physical_cpus=64)
ram = plan["tiers"]["ram"]
# RAM budget never over-allocated: dense + runtime + cache <= budget.
allocated = (ram["dense_bytes"] + ram["runtime_bytes"]
+ ram["expert_cache_bytes"])
self.assertLessEqual(allocated, ram["budget_bytes"],
f"over-allocated RAM at {ram_gb} GB")
# Every expert byte is accounted for exactly once across the tiers.
tiers = plan["tiers"]
tiered = (tiers["vram"]["hot_expert_bytes"]
+ ram["warm_expert_bytes"]
+ tiers["disk"]["cold_expert_bytes"])
self.assertEqual(tiered, plan["model"]["expert_bytes"],
f"expert bytes lost/duplicated at {ram_gb} GB")
# A positive RAM budget yields a non-negative cache and a sensible cap.
self.assertGreaterEqual(ram["expert_cache_bytes"], 0)
self.assertGreaterEqual(ram["cache_slots_per_layer"], 0)
def test_filters_requested_devices(self):
gpus = [{"index": 0, "name": "a", "total_bytes": 8 * GB, "free_bytes": 8 * GB}]
plan = build_plan(self.model, available_memory=16 * GB, available_disk=1,
@@ -117,13 +192,13 @@ class ResourcePlanTest(unittest.TestCase):
self.assertEqual(env["COLI_CUDA"], "1")
self.assertEqual(env["COLI_GPUS"], "1")
self.assertEqual(env["OMP_NUM_THREADS"], str(plan["cpu"]["physical_cores"]))
if sys.platform == "win32":
# MinGW libgomp: niente affinity su Windows, le chiavi non vanno emesse
self.assertNotIn("OMP_PROC_BIND", env)
self.assertNotIn("OMP_PLACES", env)
else:
self.assertEqual(env["OMP_PROC_BIND"], "spread")
self.assertEqual(env["OMP_PLACES"], "cores")
# The plan must NOT set OMP_PROC_BIND / OMP_PLACES on any platform:
# the engine's own hot-thread tuning owns affinity (it prefers
# OMP_PROC_BIND=close for the back-to-back per-expert matmuls). Setting
# spread + cores here ran before the engine's overwrite=0 setenv and so
# won, collapsing the team to one CPU on some libgomp topologies (#325).
self.assertNotIn("OMP_PROC_BIND", env)
self.assertNotIn("OMP_PLACES", env)
self.assertEqual(env["PIN_GB"], env["CUDA_EXPERT_GB"])
explicit_threads = environment_for_plan(plan, {"OMP_NUM_THREADS": "7",
@@ -253,5 +328,73 @@ class ResourcePlanTest(unittest.TestCase):
self.assertIn("expected_bottleneck", plan)
class PhysicalCpuCountTest(unittest.TestCase):
"""Regression for #325: --auto-tier pinned decode to one core because
physical_cpu_count() silently returned 1.
Two root causes this locks down:
1. lscpu -p prepends a CPU column, so `-p=core,socket` emits
CPU,Core,Socket; counting rows counted logical SMT siblings.
2. any probe failure fell through to ``os.cpu_count() or 1`` and the
``or 1`` could pin a constrained/cgroup'd box to a single core.
"""
def _lscpu(self, stdout):
return subprocess.CompletedProcess(args=[], returncode=0,
stdout=stdout, stderr="")
def _lscpu_topology(self, sockets, cores_per_socket, threads_per_core):
# Real lscpu shape: socket-local core IDs repeat across sockets; the
# CPU column (always prepended) is a unique logical-CPU index.
rows, cpu = [], 0
for sock in range(sockets):
for core in range(cores_per_socket):
for _ in range(threads_per_core):
rows.append(f"{cpu},{core},{sock}")
cpu += 1
return "# CPU,Core,Socket\n" + "\n".join(rows)
def test_counts_physical_cores_not_smt_threads(self):
blob = self._lscpu_topology(sockets=2, cores_per_socket=16, threads_per_core=2)
with mock.patch("resource_plan.subprocess.run", return_value=self._lscpu(blob)), \
mock.patch.object(sys, "platform", "linux"):
self.assertEqual(physical_cpu_count(), 32)
def test_single_socket_no_smt(self):
blob = self._lscpu_topology(sockets=1, cores_per_socket=8, threads_per_core=1)
with mock.patch("resource_plan.subprocess.run", return_value=self._lscpu(blob)), \
mock.patch.object(sys, "platform", "linux"):
self.assertEqual(physical_cpu_count(), 8)
def test_skips_offline_core_socket_fields(self):
# VMs / large NUMA boxes emit "-" for offline core or socket IDs; that
# used to raise ValueError, discard the whole parse, and fall through
# to the single-core fallback.
blob = "# CPU,Core,Socket\n0,0,0\n1,-,0\n2,1,0\n3,1,0\n"
with mock.patch("resource_plan.subprocess.run", return_value=self._lscpu(blob)), \
mock.patch.object(sys, "platform", "linux"):
self.assertEqual(physical_cpu_count(), 2)
def test_lscpu_missing_falls_back_to_logical_not_silent_one(self):
# The bug: lscpu absent -> os.cpu_count() or 1. On a constrained box
# os.cpu_count() can be 1. We still must never silently pick 1 without
# a warning, and when logical cores exist they must be used.
import os
with mock.patch("resource_plan.subprocess.run", side_effect=FileNotFoundError), \
mock.patch.object(sys, "platform", "linux"), \
mock.patch("resource_plan.os.cpu_count", return_value=16), \
mock.patch("sys.stderr"):
self.assertEqual(physical_cpu_count(), 16)
def test_zero_logical_cores_warns_and_returns_one(self):
# The genuine degenerate case: no probe works and os.cpu_count() is
# None/1. Must return 1 (engine needs a positive team size) but warn.
with mock.patch("resource_plan.subprocess.run", side_effect=FileNotFoundError), \
mock.patch.object(sys, "platform", "linux"), \
mock.patch("resource_plan.os.cpu_count", return_value=None), \
mock.patch("sys.stderr"):
self.assertEqual(physical_cpu_count(), 1)
if __name__ == "__main__":
unittest.main()