scripts/cpu-perf-check

@@ -1,159 +0,0 @@
-#!/usr/bin/env python3
-# tractor: distributed structured concurrency.
-# Copyright 2018-eternity Tyler Goodlet.
-#
-# SPDX-License-Identifier: AGPL-3.0-or-later
-'''
-`cpu-perf-check` — sustained-load CPU throttle detector.
-
-Idle freq snapshots LIE. A laptop can read
-`governor=performance`, `EPP=performance`,
-`platform_profile=performance`, `scaling_max_freq=<full>`
-and momentarily clock a P-core at 5GHz — while a
-firmware/EC power cap (AMD PPT/STAPM and friends) clamps
-the whole package to ~1.5GHz the instant a sustained
-multi-core load lands. That throttle masquerades as a
-`trio`-backend test *regression*: a wave of `fail_after` /
-`TooSlowError` / `Cancelled(source='deadline')` deadline
-misses on spawn-heavy tests, on byte-identical code that
-was green yesterday.
-
-The existing `tests/conftest.py:cpu_scaling_factor()` only
-reads STATIC `scaling_max_freq` vs `*_pstate_max_freq`, so
-it returns `1.0` (no throttle) during exactly this failure
-— it can't see the cap. This script complements it by
-BURNING every core for a few seconds and sampling the
-ACHIEVED `scaling_cur_freq`, which is the only thing that
-exposes the clamp.
-
-Exit code: `0` if sustained perf looks restored, `1` if
-throttled — so it gates a test run:
-
-    py313/bin/python scripts/cpu-perf-check && pytest tests/ ...
-
-Tunables (env-overridable):
-    CPU_PERF_SECS        load duration       (default 4.0)
-    CPU_PERF_HEALTHY_FRAC sustained/max floor (default 0.45)
-
-'''
-from __future__ import annotations
-import glob
-import os
-import time
-import multiprocessing as mp
-
-
-def _read(path: str) -> str | None:
-    try:
-        with open(path) as f:
-            return f.read().strip()
-    except OSError:
-        return None
-
-
-def _cur_freqs_mhz() -> list[int]:
-    out: list[int] = []
-    for f in glob.glob(
-        '/sys/devices/system/cpu/cpu[0-9]*/cpufreq/scaling_cur_freq'
-    ):
-        if (v := _read(f)):
-            out.append(int(v) // 1000)
-    return out
-
-
-def _pkg_max_mhz() -> int:
-    '''
-    Highest per-core ceiling across the package — the
-    P-core max on hybrid parts.
-
-    '''
-    mxs: list[int] = []
-    for f in glob.glob(
-        '/sys/devices/system/cpu/cpu[0-9]*/cpufreq/scaling_max_freq'
-    ):
-        if (v := _read(f)):
-            mxs.append(int(v) // 1000)
-    return max(mxs) if mxs else 0
-
-
-def _burn(stop: float) -> None:
-    x: int = 1
-    while time.perf_counter() < stop:
-        x += x * x ^ 0x5
-
-
-def main(
-    secs: float = float(os.environ.get('CPU_PERF_SECS', 4.0)),
-    # sustained aggregate must clear this fraction of the
-    # package max-freq ceiling. Throttled (~1.5GHz of 5.1GHz)
-    # ~= 0.29; a healthy all-core load easily clears 0.5.
-    healthy_frac: float = float(
-        os.environ.get('CPU_PERF_HEALTHY_FRAC', 0.45)
-    ),
-) -> int:
-    if not glob.glob('/sys/devices/system/cpu/cpu0/cpufreq'):
-        print('no cpufreq sysfs (non-linux?) — skipping, assume OK')
-        return 0
-
-    b: str = '/sys/devices/system/cpu/cpu0/cpufreq/'
-    pkg_max: int = _pkg_max_mhz()
-    print('=== static knobs (ALL can read fine while throttled) ===')
-    print(f'  governor          : {_read(b + "scaling_governor")}')
-    print(f'  EPP               : {_read(b + "energy_performance_preference")}')
-    print(f'  platform_profile  : '
-          f'{_read("/sys/firmware/acpi/platform_profile")}')
-    print(f'  pkg max freq      : {pkg_max} MHz')
-
-    ncpu: int = os.cpu_count() or 1
-    print(f'\n=== sustained {ncpu}-core load ({secs:.0f}s) — the real test ===')
-    stop: float = time.perf_counter() + secs
-    procs = [
-        mp.Process(target=_burn, args=(stop,))
-        for _ in range(ncpu)
-    ]
-    for p in procs:
-        p.start()
-
-    # skip the initial ~0.6s ramp, then sample steady-state
-    samples: list[int] = []
-    time.sleep(0.6)
-    while time.perf_counter() < stop - 0.2:
-        if (fr := _cur_freqs_mhz()):
-            samples.append(sum(fr) // len(fr))
-        time.sleep(0.3)
-    for p in procs:
-        p.join()
-
-    if not (samples and pkg_max):
-        print('  could not sample cur freq — assume OK')
-        return 0
-
-    sustained: int = sum(samples) // len(samples)
-    frac: float = sustained / pkg_max
-    print(f'  aggregate cur-freq samples: {samples}')
-    print(f'  sustained avg             : {sustained} MHz '
-          f'({frac * 100:.0f}% of {pkg_max} MHz max)')
-
-    if frac < healthy_frac:
-        print(
-            f'\n  ❌ THROTTLED — sustained {sustained}MHz is only '
-            f'{frac * 100:.0f}% of max (< {healthy_frac * 100:.0f}%).\n'
-            f'     Power cap (PPT/STAPM) still engaged. Fixes:\n'
-            f'       - bounce /sys/firmware/acpi/platform_profile\n'
-            f'         (balanced -> performance)\n'
-            f'       - unplug/replug USB-C to re-negotiate PD\n'
-            f'       - ryzenadj to lift STAPM/PPT\n'
-            f'       - else reboot\n'
-            f'     Do NOT bump test budgets — the box is slow, not the code.'
-        )
-        return 1
-
-    print(
-        f'\n  ✅ PERF OK — sustained {sustained}MHz holds '
-        f'{frac * 100:.0f}% of max. Cap looks lifted; safe to run tests.'
-    )
-    return 0
-
-
-if __name__ == '__main__':
-    raise SystemExit(main())

tests/conftest.py

@@ -120,139 +120,6 @@ def cpu_scaling_factor() -> float:
     return 1.
 
 
-# session-cached sustained-load throttle multiplier — measured
-# once (lazily) on the first `cpu_perf_headroom()` call. `None`
-# = not-yet-measured.
-_sustained_headroom: float|None = None
-
-
-def _measure_sustained_headroom(
-    secs: float = 0.9,
-    # a healthy all-core sustained clock holds AT/ABOVE this
-    # fraction of the package single-core max ceiling (boost sags
-    # under full multi-core load even un-throttled, but not far);
-    # at/above it we assume no throttle and return 1.0.
-    throttle_gate: float = 0.6,
-    max_headroom: float = 4.,
-) -> float:
-    '''
-    One-shot all-core burn returning a latency multiplier
-    (>= 1.0) that reflects *sustained-load* CPU throttle.
-
-    Catches the firmware/EC power-cap clamp (AMD PPT/STAPM &
-    friends) that pins achieved `scaling_cur_freq` to a fraction
-    of the ceiling under multi-core load while EVERY static knob
-    (`governor`, `scaling_max_freq`, `EPP`, `platform_profile`)
-    still reads "full performance". That cap is INVISIBLE to
-    `cpu_scaling_factor()` and is the gremlin behind mass `trio`
-    deadline-miss failures on byte-identical code — see
-    `scripts/cpu-perf-check`.
-
-    Best-effort: returns 1.0 on non-linux / missing sysfs / any
-    error so it can never break a test run.
-
-    '''
-    import glob
-    import multiprocessing as mp
-
-    def _read_mhz(path: str) -> int|None:
-        try:
-            return int(open(path).read()) // 1000
-        except OSError:
-            return None
-
-    try:
-        maxs: list[int] = [
-            v for f in glob.glob(
-                '/sys/devices/system/cpu/cpu[0-9]*/cpufreq/scaling_max_freq'
-            )
-            if (v := _read_mhz(f)) is not None
-        ]
-        pkg_max: int = max(maxs) if maxs else 0
-        if not pkg_max:
-            return 1.
-
-        def _burn(stop: float) -> None:
-            x: int = 1
-            while time.perf_counter() < stop:
-                x += x * x ^ 0x5
-
-        # explicit `fork` ctx so we're immune to whatever global
-        # mp start-method tractor/the suite may have set (`spawn`
-        # would re-exec + re-import 24x — slow and pointless here).
-        ctx = mp.get_context('fork')
-        ncpu: int = os.cpu_count() or 1
-        stop: float = time.perf_counter() + secs
-        procs = [
-            ctx.Process(target=_burn, args=(stop,), daemon=True)
-            for _ in range(ncpu)
-        ]
-        for p in procs:
-            p.start()
-
-        # skip the ~0.4s boost window so we sample the steady
-        # state AFTER any power-cap has engaged.
-        samples: list[int] = []
-        time.sleep(0.4)
-        while time.perf_counter() < stop - 0.1:
-            curs: list[int] = [
-                v for f in glob.glob(
-                    '/sys/devices/system/cpu/cpu[0-9]*/cpufreq/scaling_cur_freq'
-                )
-                if (v := _read_mhz(f)) is not None
-            ]
-            if curs:
-                samples.append(sum(curs) // len(curs))
-            time.sleep(0.15)
-        for p in procs:
-            p.join()
-
-        if not samples:
-            return 1.
-        frac: float = (sum(samples) // len(samples)) / pkg_max
-        # below the gate we read it as a power-cap throttle. The
-        # spawn/IPC/fork-bound work these budgets guard slows ~1:1
-        # with the achieved-vs-max freq ratio, so compensate by the
-        # FULL inverse fraction (a boost-discounted factor
-        # under-shoots and still trips the marginal cases).
-        if frac >= throttle_gate:
-            return 1.
-        return min(max_headroom, 1. / frac)
-
-    except Exception:
-        return 1.
-
-
-def cpu_perf_headroom() -> float:
-    '''
-    Latency-headroom multiplier (>= 1.0) covering BOTH cpu-perf
-    throttle classes — multiply a test's deadline by it, e.g.
-    `timeout *= cpu_perf_headroom()`:
-
-      - static cpu-freq scaling — via `cpu_scaling_factor()`
-        (governor/policy lowered the `scaling_max_freq` ceiling).
-
-      - sustained-load power-cap throttle — via
-        `_measure_sustained_headroom()` (firmware/EC PPT/STAPM
-        clamps achieved freq under load while every static knob
-        reads "performance"; INVISIBLE to the static check). This
-        is the gremlin behind mass `trio` deadline-miss failures
-        on unchanged code — see
-        `ai/conc-anal/trio_033_cancel_cascade_slowdown_depth3_issue.md`.
-
-    The sustained probe runs ONCE per session (cached); the cost
-    is a ~0.9s all-core burn on first call only.
-
-    '''
-    global _sustained_headroom
-    static: float = cpu_scaling_factor()
-    if _non_linux:
-        return static
-    if _sustained_headroom is None:
-        _sustained_headroom = _measure_sustained_headroom()
-    return max(static, _sustained_headroom)
-
-
 # NOTE, the `--ll`/`--tl` CLI flags + the `loglevel`, `test_log`
 # and `testing_pkg_name` fixtures have been factored into the
 # `tractor._testing.pytest` plugin (loaded via the `-p` entry in

tests/devx/test_debugger.py

@@ -794,14 +794,6 @@ def test_multi_nested_subactors_error_through_nurseries(
         loglevel='pdb',
     )
     last_send_char: str|None = None
-
-    # inflate pexpect waits under CPU throttle — incl. the
-    # sustained-load power-cap invisible to static freq reads — so
-    # a slow-to-boot child REPL doesn't trip a false `TIMEOUT`.
-    # See `scripts/cpu-perf-check`.
-    from ..conftest import cpu_perf_headroom
-    headroom: float = cpu_perf_headroom()
-
     for (
         i,
         send_char,
@@ -825,9 +817,6 @@ def test_multi_nested_subactors_error_through_nurseries(
         if is_forking_spawner:
             timeout += 4
 
-        if headroom != 1.:
-            timeout *= headroom
-
         try:
             child.expect(
                 PROMPT,

tests/test_advanced_streaming.py

@@ -188,18 +188,11 @@ def test_dynamic_pub_sub(
     # sits forever until external SIGINT. The `afk_alarm_w_trace`
     # outer guard below is the AFK-safety counterpart (SIGALRM
     # raises in the main thread regardless of trio scope state).
-    fail_after_s: float = (
+    fail_after_s: int = (
         8
         if is_forking_spawner
         else 20
     )
-    # inflate under CPU throttle — incl. the sustained-load
-    # power-cap invisible to static freq reads — so a slow box
-    # doesn't trip the deadline. See `scripts/cpu-perf-check`.
-    from .conftest import cpu_perf_headroom
-    headroom: float = cpu_perf_headroom()
-    if headroom != 1.:
-        fail_after_s *= headroom
 
     async def main():
         # bug-class-3 breadcrumb: tag each level of the cancel path

tests/test_cancellation.py

@@ -592,15 +592,6 @@ async def test_nested_multierrors(
     # depth=3, BOTH variants will reliably `xpass` and
     # pytest will yell — our signal to drop the marker. See
     # `ai/conc-anal/cancel_cascade_too_slow_under_main_thread_forkserver_issue.md`.
-    #
-    # Probe CPU throttle ONCE up-front (folds in the sustained-load
-    # power-cap that static freq reads miss): used BOTH to inflate
-    # the deadline budget below AND to xfail depth=3, whose failure
-    # mode under throttle is a runtime-internal reap deadline — not
-    # a test-budget miss. See `scripts/cpu-perf-check`.
-    from .conftest import cpu_perf_headroom
-    headroom: float = cpu_perf_headroom()
-
     if start_method == 'main_thread_forkserver':
         request.node.add_marker(
             pytest.mark.xfail(
@@ -614,34 +605,6 @@ async def test_nested_multierrors(
             )
         )
 
-    # Under CPU throttle (incl. the sustained-load power-cap that
-    # static freq reads miss) the DEEP depth=3 tree trips tractor's
-    # INTERNAL reap deadlines (`soft_kill`/`hard_kill`
-    # `move_on_after`/`terminate_after=1.6`) before slow subprocs
-    # exit, injecting a `Cancelled(source='deadline')` into the BEG
-    # — the SAME shape-mismatch class as the MTF xfail above, and
-    # NOT fixable by inflating the test-level budget (the Cancelled
-    # is minted inside the runtime, not by our `fail_after`).
-    # xfail(strict=False) so it auto-clears the moment the box is
-    # un-throttled (`headroom == 1.`); depth=1's shallow tree stays
-    # under those internal deadlines so it just rides the budget
-    # inflation below. See `scripts/cpu-perf-check`.
-    elif (
-        depth == 3
-        and
-        headroom != 1.
-    ):
-        request.node.add_marker(
-            pytest.mark.xfail(
-                strict=False,
-                reason=(
-                    'CPU throttled — tractor reap deadline injects '
-                    'Cancelled into BEG; see conc-anal/'
-                    'trio_033_cancel_cascade_slowdown_depth3_issue.md'
-                ),
-            )
-        )
-
     # Per-backend/-depth budgets: in the non-hang case the
     # whole spawn + cancel-cascade should complete in well
     # under these. On the borderline hang case the
@@ -669,11 +632,6 @@ async def test_nested_multierrors(
         case ('main_thread_forkserver', 3):
             timeout = 30
 
-    # inflate the budget by the throttle headroom probed above so
-    # a slow box doesn't masquerade as a deadline regression.
-    if headroom != 1.:
-        timeout *= headroom
-
     async with fail_after_w_trace(timeout):
         try:
             async with tractor.open_nursery() as nursery:

tests/test_clustering.py

@@ -24,14 +24,8 @@ def test_empty_mngrs_input_raises(
             'actor-cluster teardown hangs intermittently on UDS'
         )
 
-    # inflate under CPU throttle — incl. the sustained-load
-    # power-cap invisible to static freq reads. See
-    # `scripts/cpu-perf-check`.
-    from .conftest import cpu_perf_headroom
-    fail_after_s: float = 3 * cpu_perf_headroom()
-
     async def main():
-        with trio.fail_after(fail_after_s):
+        with trio.fail_after(3):
             async with (
                 open_actor_cluster(
                     modules=[__name__],
@@ -99,13 +93,6 @@ async def test_streaming_to_actor_cluster(
         10 if is_forking_spawner
         else 6
     )
-    # inflate under CPU throttle — incl. the sustained-load
-    # power-cap invisible to static freq reads. See
-    # `scripts/cpu-perf-check`.
-    from .conftest import cpu_perf_headroom
-    headroom: float = cpu_perf_headroom()
-    if headroom != 1.:
-        delay *= headroom
     with trio.fail_after(delay):
         async with (
             open_actor_cluster(modules=[__name__]) as portals,

tractor/_root.py

@@ -155,6 +155,7 @@ async def maybe_block_bp(
             os.environ.pop('PYTHONBREAKPOINT', None)
 
 
+
 @acm
 async def open_root_actor(
     *,
@@ -185,7 +186,6 @@ async def open_root_actor(
     # enables the multi-process debugger support
     debug_mode: bool = False,
     maybe_enable_greenback: bool = False,  # `.pause_from_sync()/breakpoint()` support
-
     # ^XXX NOTE^ the perf implications of use,
     # https://greenback.readthedocs.io/en/latest/principle.html#performance
     enable_stack_on_sig: bool = False,

tractor/runtime/_state.py

@@ -140,7 +140,7 @@ _RUNTIME_VARS_DEFAULTS: dict[str, Any] = {
     # `debug_mode: bool` settings
     '_debug_mode': False,  # bool
     'repl_fixture': False,  # |AbstractContextManager[bool]
-
+    
     'use_greenback': False,  # `.pause_from_sync()`/`breakpoint()`
     'use_stackscope': False,  # trio-task-stack dumps on SIGUSR1