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perfcheck: nightly fleet GPU canary + the contention lessons that shaped it

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BENCHMARKS.md says what a model cost the day it was measured; nothing noticed if a
macOS/torch update or a thermal fault halved a node. perfcheck runs the whole fleet
in ~35s off godcheck's 03:30 cron on the m4mini and reports drift into
GODCHECK_LATEST.md.

Probes matmul (fp16/fp32), memory bandwidth, and SDPA at head_dim 64 vs 56 — the
latter turning CorridorKey's fast-path cliff into a permanent canary: it confirms
the padding win fleet-wide (1.96x-5.26x) and tells us if a future torch closes it.
Runs on venvs/rmbg/bin/python, already identical fleet-wide, so nothing new is
installed (nothing lands on the disk-tight m1max).

First cross-machine capability table for all 6 nodes. The M3 Ultra is ~2.2x the M1
Ultra on fp16 matmul, but they share ~625 GB/s — so bandwidth-bound stages run alike
while compute-bound ones scale. Both Ultras reach only ~78% of spec bandwidth on a
single kernel; the smaller Macs hit ~88%.

Measuring a fleet that is doing real work is the whole problem, and naive
benchmarking here is off by 11x:

- min, not median: a concurrent trellis_mac job dragged a median-of-5 matmul from
  ~24500 to ~2150 GFLOP/s, which reads exactly like a catastrophic regression.
- n=4096 not 2048: 2048 is dispatch-bound and swung 48% run-to-run; 4096 reproduces
  to 0.1% even while contended.
- sdpa 16x2048 not 8x1024: sub-ms probes are dispatch noise — 8x1024 gave ratios of
  0.79/3.95/2.35 on three runs of one machine, the first "proving" 56 is faster.
- busy nodes are excluded, not blamed: GPU contention is invisible to load average
  (M3 Ultra read load 2.45 with its GPU pinned), so bench.py samples ioreg GPU% before
  it touches the GPU — our own matmul pins the device, so ordering is the trick.
- baselines are the median of recent history, not a saved best: the M4 Pro also serves
  Ollama and is bimodal (~3200 vs ~5500 fp32), so a best-observed baseline pins to a
  lucky outlier and alerts forever.
- a regression must repeat before it is believed ([~] watching -> [!] CONFIRMED).

Validated by re-running the fleet against its own baselines: zero false alarms,
including a sweep where the M3 Ultra read 43 GB/s under load and was correctly
marked BUSY rather than reported as a 93% regression.

Also found: the m4mini is the only node with Tailscale SSH (RunSSH: true) and it does
NOT propagate remote exit codes — `ssh m4mini "exit 7"` returns 0, so any
`if ssh m4mini ...` test silently always passes. Test on output instead, which is
what godcheck already does (and why it is unaffected). It also cannot ssh to itself,
so run_fleet detects its own tailnet IP and benches the local node via the shell.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
This commit is contained in:
m3ultra 2026-07-17 16:50:06 +10:00
parent f6626f0a06
commit 27564e80eb
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6
.gitignore vendored
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@ -40,3 +40,9 @@ bin/brush-app-aarch64-apple-darwin/
# GPU worker-pool config — primary only (a leaf worker must NOT have this)
nodes.json
# perfcheck runtime state — per-runner, not shared. The authoritative copy lives on the
# m4mini watchdog; baselines.json is derived from history.jsonl and regenerated each run.
scripts/perfcheck/history.jsonl
scripts/perfcheck/baselines.json
scripts/perfcheck/pending.json

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BENCHMARKS.md
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@ -114,7 +114,36 @@ Raised the config from the laptop-tuned defaults to `octree_resolution 384` + `r
2. Either `huggingface-cli login` on the machine, or paste an HF token into
Settings → "HuggingFace token" (injected as `HF_TOKEN` for the operators).
## Fleet hardware baseline (perfcheck, torch 2.13.0/MPS, 2026-07-17)
What each node's GPU is *capable* of, independent of any model — the denominator for every
number above, and the reference for "is this machine still healthy". Measured nightly by
`scripts/perfcheck/`; see **[PERFCHECK.md](PERFCHECK.md)** for the full story.
| node | chip | RAM | matmul fp16 | bandwidth | sdpa 56/64 |
|---|---|---|---|---|---|
| m3ultra | M3 Ultra | 256GB | 25202 | 627 GB/s | 4.35x |
| m1 | M1 Ultra | 128GB | ~17100 | 639 GB/s | 3.89x |
| studio | M1 Max | 32GB | 6996 | 348 GB/s | 3.09x |
| m4 | M4 Pro | 24GB | 5678 | 241 GB/s | 1.96x |
| m4mini | M4 | 16GB | 3774 | 105 GB/s | 5.10x |
| mini | M1 (2020) | 8GB | 2310 | 61 GB/s | 5.26x |
GFLOP/s. The M3 Ultra is **~2.2x** the M1 Ultra on fp16 matmul but they share the same ~625
GB/s memory bandwidth — so bandwidth-bound stages (VAE decode, big texture bakes) run at
similar speed on both, while compute-bound ones (denoise) scale with the newer silicon. Both
Ultras reach only ~78% of their ~800 GB/s spec on a single kernel; the smaller Macs hit ~88%.
`sdpa 56/64` is the fused-attention cliff at CorridorKey's awkward `head_dim=56` — it's why
padding to 64 wins (`CORRIDORKEY.md`), reproduced independently on all 6 nodes, and it is
watched nightly so we learn if a future torch ever closes it.
## Method
Timings are wall-clock from the job runner (`started_at`→`finished_at`), single
job at a time (gpu lane = 1). Re-run `tests/smoke.sh` for the framework
regression suite (12 checks, ~30s).
**Benchmarking on this fleet is contended.** These are working machines; a neighbouring job
can make a node look 5–11x slower and it is invisible to load average (the M3 Ultra reads load
2.45 with its GPU pinned). Anything measured here should use min-of-runs and check
`ioreg … IOAccelerator` "Device Utilization %" *before* touching the GPU. See PERFCHECK.md.

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# PERFCHECK — nightly GPU performance canary across the fleet
`BENCHMARKS.md` is a *snapshot*: what each model cost on the day it was measured. Perfcheck is
the *tripwire*. A macOS point update, a torch/MLX bump, or a thermal fault can halve a node's
throughput, and nothing else in the fleet would notice — you'd just quietly wait twice as long
for every render until someone got suspicious months later. This catches it the next morning.
It runs as part of godcheck on the m4mini watchdog (`~/godcheck/nightly.sh`, cron 03:30),
and appends a table + drift lines to `~/Documents/GODCHECK_LATEST.md` on ultra. Whole fleet,
6 nodes, **~35s**.
## The numbers (torch 2.13.0 / MPS, 2026-07-17)
Every node runs `MODELBEAST/venvs/rmbg/bin/python` — the same torch is already installed
fleet-wide, so nothing new gets installed (notably nothing lands on the disk-tight m1max).
| node | chip | RAM | matmul fp16 | matmul fp32 | bandwidth | sdpa 64 | sdpa 56 | **56/64** |
|---|---|---|---|---|---|---|---|---|
| **m3ultra** | M3 Ultra | 256GB | 25202 | 22995 | 627 GB/s | 0.98ms | 4.27ms | **4.35x** |
| **m1** | M1 Ultra | 128GB | ~17100 | ~16000 | 639 GB/s | 1.50ms | 5.83ms | **3.89x** |
| **studio** | M1 Max | 32GB | 6996 | 6538 | 348 GB/s | 3.48ms | 10.73ms | **3.09x** |
| **m4** | M4 Pro | 24GB | 5678 | 3869 | 241 GB/s | 6.59ms | 12.88ms | **1.96x** |
| **m4mini** | M4 | 16GB | 3774 | 3436 | 105 GB/s | 5.46ms | 27.83ms | **5.10x** |
| **mini** | M1 (2020) | 8GB | 2310 | 1781 | 61 GB/s | 9.88ms | 51.84ms | **5.26x** |
GFLOP/s, higher better. m1/m3ultra are *best observed* rather than medians — both were serving
real work all session (see "busy nodes" below), so their baselines are still warming up.
Bandwidth tracks spec closely on the small machines — mini 61/68 GB/s (89%), m4mini 105/120
(88%), m4 241/273 (88%), studio 348/400 (87%) — but **both Ultras land near 625 GB/s against a
spec of ~800**, i.e. ~78%. A single `add_` kernel doesn't saturate the Ultra fabric; that's a
property of the interconnect, not a fault, and it is the number to beat if a workload ever
needs to.
### The 56/64 column is the point
CorridorKey's Hiera backbone uses `head_dim=56`, which misses the fused-attention fast path on
Apple Silicon — padding to 64 is why our fork is 1.3x–4.9x faster (see `CORRIDORKEY.md`). This
bench reproduces that cliff directly and independently, on every machine, every night:
- It confirms the padding win is real fleet-wide (**1.96x–5.26x**, never below 1).
- **If a future torch closes the gap, this column collapses toward 1.0 and we find out** —
instead of carrying a workaround forever without noticing it became unnecessary.
The M4 Pro benefits least (1.96x); the small M4/M1 benefit most (>5x). Note these are pure
microbenchmark ratios — a full CorridorKey run dilutes them with non-attention work, so they
run higher than the end-to-end gains in `CORRIDORKEY.md`.
## Usage
```sh
scripts/perfcheck/run_fleet.py # bench fleet, compare to history, report
scripts/perfcheck/run_fleet.py --only m1,m4 # subset
scripts/perfcheck/run_fleet.py --show # print current baselines, don't bench
scripts/perfcheck/deploy_to_watchdog.sh # push to m4mini — RE-RUN AFTER EDITING bench.py
```
Exit 1 on a confirmed regression. State (`history.jsonl`, `baselines.json`, `pending.json`) is
gitignored and per-runner; the authoritative copy lives on the m4mini.
**Editing `bench.py` changes what the numbers mean.** Bump `SCHEMA` in it (and in
`run_fleet.py`) whenever a probe's shape or size changes — older history is then ignored rather
than being median'd against a different benchmark and mistaken for a regression. Then re-run
`deploy_to_watchdog.sh`, or the fleet keeps being measured by the old bench.
## Why it's built the way it is
Everything below is a scar. The fleet runs real work while being measured, and that fact
dominates the whole design.
**Naive benchmarking here is off by 11x.** The first version reported the M3 Ultra at 2154
GFLOP/s and 84 GB/s. The true figures are ~24900 and ~620. Two causes: `n=2048` matmul is
dispatch-bound rather than compute-bound (it swung 11700 vs 17361 across runs — 48%), and
`median` lets a noisy neighbour through. `n=4096` reproduced to **0.1%** across runs *while the
GPU was contended*. Sizes here are chosen for stability, not speed — shrinking them to make the
bench faster turns it back into a random number generator.
**min, not mean/median.** A concurrent `trellis_mac` job dragged a median-of-5 matmul from
~24500 to ~2150 — a 5x error that looks exactly like a catastrophic regression. The minimum
time is the least-interfered sample and the only estimate that survives a busy neighbour.
**Sub-millisecond probes measure nothing.** The obvious sdpa size (8 heads x 1024) is ~0.4ms
and pure dispatch noise: three consecutive runs on one machine gave ratios of 0.79, 3.95 and
2.35 — the first would have "proven" head_dim=56 is *faster*, contradicting the real 8-machine
result. At 16 x 2048 it lands ~1-4ms and reproduces to 0.6%.
**Busy nodes are excluded, not blamed.** GPU contention is invisible to load average — the M3
Ultra sat at **load 2.45 with its GPU fully pinned** by trellis_mac. So `bench.py` samples GPU
utilization from `ioreg` *before it touches the GPU* (our own matmul pins the device at ~100%,
so sampling during the run cannot separate us from a neighbour — the ordering is the whole
trick). Above 50% the node is marked `[~] BUSY`, and its numbers raise no alert and never enter
a baseline. Two quirks: the first `ioreg` read is garbage (it is since-last-read, and an idle
m4mini reported 97% cold), and a GPU job alternates phases (100% CPU / 0% GPU one moment, 97%
GPU the next) — hence discard-first and max-of-several.
**Baselines are the median of recent history, not a saved "best".** These machines have
neighbours: the M4 Pro also serves Ollama and its fp32 is bimodal (~3200 vs ~5500 depending on
whether a request is in flight); the M1 Ultra runs `mrpgi` on its GPU and swings 8301–15891
(1.9x). A best-observed baseline pins to a lucky outlier the node rarely reaches again — which
means alerting every night forever. A median is what the machine actually does.
**A regression must repeat before it's believed.** Transient contention is far more common than
real regression and doesn't recur on schedule. First sighting is `[~] watching`; only a second
consecutive one is `[!] CONFIRMED` and fails the run. Getting *faster* is reported immediately
— it's never an alarm.
## Fleet gotcha found while building this
**The m4mini is the only node with Tailscale SSH enabled (`RunSSH: true`), and it does not
propagate remote exit codes.** `ssh m4mini "exit 7"` returns **0**; so does `ssh m4mini
"false"`. Every other node propagates correctly. This means **any `if ssh m4mini ...; then`
test silently always passes** — a reach-check written that way will report every node healthy
no matter what. Test on *output* instead (`x=$(ssh … && echo YES)`), which is what godcheck
already does throughout, and why godcheck is unaffected.
It also means the watchdog cannot ssh to *itself* ("Host key verification failed"), so
`run_fleet.py` detects its own tailnet IP and benches the local node through the shell instead.
Worth deciding: `tailscale set --ssh=false` on the m4mini would make it behave like the rest of
the fleet, but it's a live config change on the always-on watchdog and hasn't been made.

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"""PERFCHECK — per-node GPU performance canary. Prints one JSON object to stdout.
Runs on ``MODELBEAST/venvs/rmbg/bin/python``, which carries an identical torch on every node
in the fleet — so numbers are comparable machine-to-machine without installing anything new
(nothing lands on the disk-critical m1max).
Probes (~20s, sized to survive the 8GB M1 mini):
matmul_fp16 / matmul_fp32 GFLOP/s — raw compute
bandwidth GB/s — unified-memory read/write
sdpa_64 / sdpa_56 ms — attention at a fast-path head_dim (64) vs the
awkward one CorridorKey's Hiera actually uses (56)
The sdpa pair is the point. CorridorKey is slow on Apple Silicon because head_dim=56 misses
the fused attention path; padding to 64 buys 1.3x-4.9x depending on the machine. ``sdpa_ratio``
(56/64) tracks that cliff per node, so if a future torch closes it we find out — instead of
carrying the padding workaround forever without noticing it became unnecessary.
MEASUREMENT NOTES — these are load-bearing, do not "simplify" them:
* **min, not mean/median.** These nodes serve jobs. A concurrent trellis_mac run on the M3 Ultra
dragged a median-of-5 matmul from ~24500 down to ~2150 GFLOP/s — a 5x error that looks
exactly like a catastrophic regression. The minimum time is the least-interfered sample and
the only estimate of the machine's actual capability that survives a noisy neighbour.
* **Sizes are chosen for stability, not for speed.** n=4096 reproduced to within 0.1% across
runs *while the GPU was contended*; n=2048 swung 48% (11700 vs 17361) because it is
dispatch-bound rather than compute-bound. Shrinking these to make the bench faster silently
turns it back into a random number generator.
* **Every probe syncs MPS before stopping the clock.** MPS dispatch is async; an unsynced timer
measures queue-submission, not work.
* ``load1`` is reported so a consumer can distrust a sample taken on a busy node. Under
contention the mins mostly hold up, but a hard-loaded node can still read low.
"""
from __future__ import annotations
import json
import os
import platform
import subprocess
import sys
import time
os.environ.setdefault("PYTORCH_ENABLE_MPS_FALLBACK", "1")
os.environ.setdefault("KMP_DUPLICATE_LIB_OK", "TRUE")
import torch # noqa: E402
# 2: matmul 2048->4096, sdpa 8x1024 -> 16x2048, median->min, added gpu_busy_pre.
SCHEMA = 2
def _sync() -> None:
torch.mps.synchronize()
def _best(fn, runs: int = 7, warmup: int = 3) -> float:
"""Fastest of ``runs`` seconds-per-call, MPS-synced. See MEASUREMENT NOTES on why min."""
for _ in range(warmup):
fn()
_sync()
best = float("inf")
for _ in range(runs):
t0 = time.perf_counter()
fn()
_sync()
best = min(best, time.perf_counter() - t0)
return best
def bench_matmul(dtype: torch.dtype, n: int = 4096) -> float:
"""GFLOP/s for an n^3 matmul. n=4096 is the smallest size that is compute- not
dispatch-bound here (~67MB/tensor fp32 — fine on the 8GB mini)."""
a = torch.randn(n, n, device="mps", dtype=dtype)
b = torch.randn(n, n, device="mps", dtype=dtype)
secs = _best(lambda: a @ b)
return (2.0 * n**3) / secs / 1e9
def bench_bandwidth(mb: int = 512) -> float:
"""GB/s. x.add_(1) reads and writes the whole buffer -> 2x bytes moved.
runs=25 rather than the default: each call is only ~1.6ms, so extra samples are nearly
free and they reject neighbour interference. At runs=9 this spread 16% on a contended
node (479 vs 570) — enough to trip a 20% drift alarm on its own. At runs=25: 0.3%.
"""
n = (mb * 1024 * 1024) // 4
x = torch.randn(n, device="mps", dtype=torch.float32)
secs = _best(lambda: x.add_(1.0), runs=25)
return (2.0 * n * 4) / secs / 1e9
def bench_sdpa(head_dim: int, heads: int = 16, seq: int = 2048) -> float:
"""Milliseconds for one fused-attention call at the given head_dim.
heads=16/seq=2048 is deliberate: it lands ~1-4ms, where the ratio reproduces to 0.6%
(4.28/4.30/4.33 across runs on a contended M3 Ultra). The obvious smaller 8x1024 is
sub-millisecond and pure dispatch noise — it produced ratios of 0.79, 3.95 and 2.35 on
three consecutive runs of the same machine, i.e. it would have "proven" head_dim=56 is
*faster*, contradicting the real 8-machine result.
"""
shape = (1, heads, seq, head_dim)
q = torch.randn(*shape, device="mps", dtype=torch.float16)
k = torch.randn(*shape, device="mps", dtype=torch.float16)
v = torch.randn(*shape, device="mps", dtype=torch.float16)
secs = _best(lambda: torch.nn.functional.scaled_dot_product_attention(q, k, v), runs=9)
return secs * 1000.0
def gpu_busy_pre() -> int:
"""Peak GPU utilization % observed over ~1.2s, sampled BEFORE any torch work starts.
Must run before we touch the GPU: our own matmul pins the device at ~100%, so this can
only tell us about a *neighbour* while we are still idle. That ordering is the whole trick
— sampling during the bench is worthless.
``load1`` cannot substitute: the M3 Ultra sat at load 2.45 with its GPU fully held by a
trellis_mac job. Conversely a GPU job alternates phases (100% CPU / 0% GPU one moment,
97% GPU the next), so a single reading misses it — hence max-of-several. The first ioreg
read is discarded because the counter is since-last-read and reports garbage when cold (an
idle m4mini reported 97% on its first sample, 0% thereafter).
"""
def sample() -> int:
try:
out = subprocess.run(
["ioreg", "-r", "-d", "1", "-w", "0", "-c", "IOAccelerator"],
capture_output=True, text=True, timeout=8,
).stdout
except Exception:
return 0
vals = [int(s.split("=")[1]) for s in out.split(",")
if s.strip().startswith('"Device Utilization %"')]
return max(vals) if vals else 0
sample() # discard the cold read
peak = 0
for _ in range(4):
time.sleep(0.3)
peak = max(peak, sample())
return peak
def _sysctl(key: str) -> str:
try:
return subprocess.run(
["sysctl", "-n", key], capture_output=True, text=True, timeout=5
).stdout.strip()
except Exception:
return ""
def host_facts() -> dict:
mem = _sysctl("hw.memsize")
return {
"host": platform.node().split(".")[0],
"chip": _sysctl("machdep.cpu.brand_string"),
"cores": _sysctl("hw.ncpu"),
"ram_gb": round(int(mem) / 1024**3) if mem.isdigit() else None,
"macos": platform.mac_ver()[0],
"torch": torch.__version__,
"load1": round(os.getloadavg()[0], 2),
}
def main() -> int:
if not torch.backends.mps.is_available():
print(json.dumps({"error": "MPS unavailable", **host_facts()}))
return 1
# Before any torch work — see gpu_busy_pre().
busy = gpu_busy_pre()
# BUMP `schema` whenever a probe's shape/size changes. Numbers are only comparable within
# a schema, and run_fleet drops older samples from the median rather than averaging a
# 2048-matmul against a 4096-matmul and calling the difference a regression.
out = {"schema": SCHEMA, **host_facts(), "gpu_busy_pre": busy, "metrics": {}}
m = out["metrics"]
m["matmul_fp16_gflops"] = round(bench_matmul(torch.float16), 1)
m["matmul_fp32_gflops"] = round(bench_matmul(torch.float32), 1)
m["bandwidth_gbs"] = round(bench_bandwidth(), 1)
sdpa64 = bench_sdpa(64)
sdpa56 = bench_sdpa(56)
m["sdpa_64_ms"] = round(sdpa64, 3)
m["sdpa_56_ms"] = round(sdpa56, 3)
# >1 means the awkward head_dim is slower, i.e. CorridorKey's padding win still stands.
m["sdpa_ratio"] = round(sdpa56 / sdpa64, 2) if sdpa64 else None
out["load1_end"] = round(os.getloadavg()[0], 2)
print(json.dumps(out))
return 0
if __name__ == "__main__":
sys.exit(main())

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#!/bin/zsh
# Push perfcheck to the m4mini watchdog, where the nightly godcheck cron runs it.
#
# Idempotent — re-run it whenever bench.py or run_fleet.py changes, otherwise the fleet keeps
# being measured by the old benchmark. Accumulated state (history/baselines/pending) is NEVER
# overwritten: on the first deploy the local history is seeded across so the baselines carry
# over, and after that the m4mini's copy is authoritative.
#
# Lives beside godcheck (~/godcheck/perfcheck) rather than in ~/MODELBEAST, to match how
# godcheck itself is a standalone script and to keep the cron independent of the repo state.
set -u
W=m4mini@100.124.220.31
DEST=godcheck/perfcheck
HERE=${0:A:h}
echo "==> deploying perfcheck to $W:~/$DEST"
ssh -o ConnectTimeout=10 -o BatchMode=yes "$W" "mkdir -p ~/$DEST"
scp -q "$HERE/bench.py" "$HERE/run_fleet.py" "$W:$DEST/"
ssh -o ConnectTimeout=10 -o BatchMode=yes "$W" "chmod +x ~/$DEST/run_fleet.py"
# Seed history only if the watchdog has none, so a redeploy never clobbers real history.
#
# Tested on OUTPUT, never on ssh's exit status: the m4mini is the one node in the fleet with
# Tailscale SSH enabled (`RunSSH: true`), and tailscaled handles the session itself rather than
# sshd — it does not propagate the remote exit code. `ssh m4mini "exit 7"` returns 0, so every
# `if ssh m4mini test ...` silently succeeds. Every other node propagates correctly. (godcheck
# is output-based throughout and is unaffected.)
have=$(ssh -o ConnectTimeout=10 -o BatchMode=yes "$W" "test -s ~/$DEST/history.jsonl && echo YES")
if [ "$have" = "YES" ]; then
echo "==> watchdog already has history — left untouched"
elif [ -s "$HERE/history.jsonl" ]; then
echo "==> seeding history.jsonl (first deploy)"
scp -q "$HERE/history.jsonl" "$W:$DEST/"
fi
echo "==> smoke test (one node)"
ssh -o ConnectTimeout=10 -o BatchMode=yes "$W" "cd ~/$DEST && /usr/bin/python3 run_fleet.py --only m4mini --quiet"
echo "==> done"

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#!/usr/bin/env python3
"""PERFCHECK fleet runner — benchmark every MODELBEAST node, detect drift, write a report.
Stdlib only, so it runs on any node's system python3 (notably the m4mini, which hosts the
godcheck cron). ``bench.py`` is copied to each node on every run, so a node can never drift
onto a stale copy of the benchmark itself.
./run_fleet.py # bench the fleet, compare against recent history, report
./run_fleet.py --only m1,m4 # subset
./run_fleet.py --show # print the current baselines and exit (no benching)
Exit 1 if any node shows a CONFIRMED regression, so cron/CI can react.
WHY IT LOOKS LIKE THIS — the fleet serves real work, and that dominates every design choice:
* **Baselines are the median of recent history, not a saved "best".** These machines have
neighbours. The M4 Pro also serves Ollama and its fp32 is bimodal (~3200 vs ~5500 GFLOP/s)
depending on whether a request is in flight; the M1 Ultra runs `mrpgi` on its GPU and swings
8301-15891 (1.9x). A best-observed baseline pins to a lucky outlier the node rarely reaches
again, which means alerting every night forever. A median is what the machine actually does.
* **A busy node is excluded, not blamed.** GPU contention is invisible to load average (the M3
Ultra read load 2.45 with its GPU pinned by trellis_mac), so bench.py samples GPU% before it
touches the GPU. Above BUSY_PCT the sample is noise: no alert, and kept out of the baseline.
* **A regression must repeat before it is believed.** Transient contention is far more common
than real regression and does not recur on schedule. First sighting is [~] watching; only a
second consecutive one is [!] CONFIRMED and fails the run.
* **Suspicious nodes are retried and the best attempt kept.** Contention only ever makes a node
look slower, so best-of-attempts is the least-interfered estimate. Only nodes that look off
pay for this, so the common case stays one pass.
"""
from __future__ import annotations
import argparse
import json
import os
import subprocess
import sys
from datetime import datetime, timezone
from pathlib import Path
HERE = Path(__file__).resolve().parent
BENCH = HERE / "bench.py"
HISTORY = HERE / "history.jsonl" # every sample ever taken, append-only
BASELINES = HERE / "baselines.json" # derived view of HISTORY, rewritten each run
PENDING = HERE / "pending.json" # breaches seen last run — see confirm()
# name -> (ssh target, MODELBEAST root). Mirrors nodes.json + the local primary. Embedded
# rather than read from nodes.json because that file is gitignored and primary-only, so the
# m4mini cron would not see it; godcheck hardcodes its hosts the same way.
NODES = [
("m3ultra", "m3ultra@100.89.131.57", "/Users/m3ultra/Documents/MODELBEAST"),
("m1", "johnking@100.91.239.7", "/Users/johnking/MODELBEAST"),
("m4", "m4pro@100.69.21.128", "/Users/m4pro/MODELBEAST"),
("studio", "studio@100.92.78.24", "/Users/studio/MODELBEAST"),
("m4mini", "m4mini@100.124.220.31", "/Users/m4mini/MODELBEAST"),
("mini", "mini@100.79.229.50", "/Users/mini/MODELBEAST"),
]
HIGHER_BETTER = {"matmul_fp16_gflops", "matmul_fp32_gflops", "bandwidth_gbs"}
# sdpa_ratio is diagnostic: a change means the fused-attention landscape moved (e.g. a torch
# release finally handles head_dim=56), which is a headline to read, not a regression to fail.
DIAGNOSTIC = {"sdpa_ratio"}
THRESHOLD = 0.20 # flag a >20% move vs baseline
BUSY_PCT = 50 # GPU% (pre-bench) above which a node is unmeasurable
HISTORY_WINDOW = 9 # samples per node the median is drawn from
MIN_SAMPLES = 3 # below this a node has no baseline yet and cannot alert
# Numbers are only comparable within a bench schema. bench.py bumps SCHEMA when a probe's
# shape changes; older history is then ignored rather than being median'd against the new
# shape and mistaken for a regression. Keep in step with bench.py's SCHEMA.
SCHEMA = 2
SSH = ["ssh", "-o", "ConnectTimeout=10", "-o", "BatchMode=yes"]
# ---------------------------------------------------------------------------
# Running
# ---------------------------------------------------------------------------
def local_ip() -> str:
"""This machine's tailnet IPv4, or "" — used to spot our own entry in NODES."""
for cmd in (["tailscale", "ip", "-4"],
["/Applications/Tailscale.app/Contents/MacOS/Tailscale", "ip", "-4"]):
try:
out = subprocess.run(cmd, capture_output=True, text=True, timeout=8)
if out.returncode == 0 and out.stdout.strip():
return out.stdout.strip().splitlines()[0].strip()
except Exception:
continue
return ""
def run_node(name: str, host: str, root: str, self_ip: str = "") -> dict:
"""Run bench.py on a node (locally if that node is us) and return parsed JSON.
Benching ourselves goes through the shell, not ssh: a host looping back to its own tailnet
address needs its own host key trusted and its own pubkey authorized, which fails out of the
box ("Host key verification failed" on the m4mini watchdog, which must bench itself as part
of the fleet). Running local also skips a pointless copy and round-trip.
"""
remote = "/tmp/perfcheck_bench.py"
is_self = bool(self_ip) and host.split("@")[-1] == self_ip
try:
if is_self:
proc = subprocess.run(
[f"{root}/venvs/rmbg/bin/python", str(BENCH)],
capture_output=True, text=True, timeout=600,
)
else:
subprocess.run(
["scp", "-q", "-o", "ConnectTimeout=10", "-o", "BatchMode=yes",
str(BENCH), f"{host}:{remote}"],
check=True, capture_output=True, timeout=60,
)
proc = subprocess.run(
SSH + [host, f"{root}/venvs/rmbg/bin/python {remote}"],
capture_output=True, text=True, timeout=600,
)
except subprocess.TimeoutExpired:
return {"node": name, "error": "timeout"}
except subprocess.CalledProcessError as e:
return {"node": name, "error": f"scp failed: {e.stderr.decode()[:120].strip()}"}
if proc.returncode != 0:
tail = (proc.stderr or proc.stdout).strip().splitlines()
return {"node": name, "error": (tail[-1][:160] if tail else f"exit {proc.returncode}")}
try:
# The bench prints one JSON object; take the last line in case a lib warns first.
return {"node": name, **json.loads(proc.stdout.strip().splitlines()[-1])}
except (ValueError, IndexError):
return {"node": name, "error": f"unparseable: {proc.stdout[:120]!r}"}
def usable(r: dict) -> bool:
"""True if a sample is trustworthy enough to compare or to feed the baseline."""
return (
"error" not in r
and r.get("schema") == SCHEMA
and r.get("gpu_busy_pre", 0) < BUSY_PCT
and bool(r.get("metrics"))
)
def merge_best(runs: list[dict]) -> dict:
"""Fold repeat attempts at one node into its least-contended sample, per metric.
Contention can only make a node look slower, never faster, so the best value across
attempts is the closest estimate of what the machine can do right now. Same argument as
min-of-runs inside bench.py, lifted one level.
"""
ok = [r for r in runs if r and "error" not in r and r.get("metrics")]
if not ok:
return runs[0]
out = dict(ok[-1])
m = {}
for key in ok[0]["metrics"]:
vals = [r["metrics"][key] for r in ok if r["metrics"].get(key) is not None]
if vals:
m[key] = max(vals) if key in HIGHER_BETTER else min(vals)
# Recompute so the ratio stays consistent with the sdpa numbers reported beside it.
if m.get("sdpa_64_ms"):
m["sdpa_ratio"] = round(m["sdpa_56_ms"] / m["sdpa_64_ms"], 2)
out["metrics"] = m
out["attempts"] = len(ok)
# Least-contended attempt wins, so carry the quietest GPU reading with it.
out["gpu_busy_pre"] = min(r.get("gpu_busy_pre", 0) for r in ok)
return out
# ---------------------------------------------------------------------------
# Baselines (derived from history)
# ---------------------------------------------------------------------------
def _median(xs: list[float]) -> float:
xs = sorted(xs)
n = len(xs)
return xs[n // 2] if n % 2 else (xs[n // 2 - 1] + xs[n // 2]) / 2.0
def baselines_from_history() -> dict:
"""node -> {metrics: {k: median-of-recent}, n: samples}. Only clean samples count."""
per_node: dict[str, list[dict]] = {}
if HISTORY.exists():
for line in HISTORY.read_text().splitlines():
try:
r = json.loads(line)
except ValueError:
continue
if usable(r):
per_node.setdefault(r["node"], []).append(r["metrics"])
out = {}
for node, samples in per_node.items():
recent = samples[-HISTORY_WINDOW:]
if len(recent) < MIN_SAMPLES:
out[node] = {"metrics": {}, "n": len(recent)}
continue
keys = {k for s in recent for k in s}
med = {}
for k in keys:
vals = [s[k] for s in recent if s.get(k) is not None]
if vals:
med[k] = round(_median(vals), 3)
out[node] = {"metrics": med, "n": len(recent)}
return out
def compare(results: list[dict], baselines: dict) -> dict[str, str]:
"""Breaches keyed ``node/metric`` -> readable line. ``{}`` when all within threshold."""
out = {}
for r in results:
if not usable(r):
continue
base = baselines.get(r["node"], {}).get("metrics")
if not base:
continue # not enough history yet
for key, now in r["metrics"].items():
was = base.get(key)
if was in (None, 0) or now is None or key in DIAGNOSTIC:
continue
change = (now - was) / was
slower = -change if key in HIGHER_BETTER else change
if slower > THRESHOLD:
out[f"{r['node']}/{key}"] = f"{r['node']} {key}: {was} -> {now} ({slower:+.0%} SLOWER)"
elif -slower > THRESHOLD:
out[f"+{r['node']}/{key}"] = f"{r['node']} {key}: {was} -> {now} ({-slower:+.0%} faster)"
return out
def confirm(breaches: dict[str, str]) -> tuple[list[str], list[str]]:
"""Split breaches into (confirmed, provisional) by whether they also fired last run.
A regression is believed only once it repeats: transient contention is the overwhelmingly
common cause of one slow sample and it does not recur on schedule, while a real regression
does. A node getting *faster* is reported immediately — it is never an alarm.
"""
try:
prev = set(json.loads(PENDING.read_text()))
except Exception:
prev = set()
confirmed, provisional = [], []
for key, line in sorted(breaches.items()):
if key.startswith("+"):
confirmed.append(f"[+] {line}")
elif key in prev:
confirmed.append(f"[!] {line} — CONFIRMED (2 runs)")
else:
provisional.append(f"[~] {line} — unconfirmed, watching")
PENDING.write_text(json.dumps([k for k in breaches if not k.startswith("+")]) + "\n")
return confirmed, provisional
# ---------------------------------------------------------------------------
# Reporting
# ---------------------------------------------------------------------------
def report(results: list[dict], confirmed: list[str], provisional: list[str],
baselines: dict, stamp: str) -> str:
out = [f"# PERFCHECK {stamp}", ""]
out.append("| node | chip | RAM | matmul fp16 | matmul fp32 | bandwidth | sdpa 64 | sdpa 56 | 56/64 |")
out.append("|---|---|---|---|---|---|---|---|---|")
for r in sorted(results, key=lambda x: x["node"]):
if "error" in r:
out.append(f"| **{r['node']}** | [X] {r['error']} | | | | | | | |")
continue
m, chip = r["metrics"], (r.get("chip") or "").replace("Apple ", "")
busy = r.get("gpu_busy_pre", 0)
if busy >= BUSY_PCT:
chip += f" [~] BUSY {busy}%"
out.append(
f"| **{r['node']}** | {chip} | {r.get('ram_gb')}GB | "
f"{m['matmul_fp16_gflops']:.0f} | {m['matmul_fp32_gflops']:.0f} | "
f"{m['bandwidth_gbs']:.0f} GB/s | {m['sdpa_64_ms']:.2f}ms | "
f"{m['sdpa_56_ms']:.2f}ms | **{m['sdpa_ratio']}x** |"
)
thin = [n for n, b in baselines.items() if b["n"] < MIN_SAMPLES]
out.append("")
out.append("## drift vs baseline (median of last %d clean runs)" % HISTORY_WINDOW)
out.extend(confirmed or ["- no confirmed regressions"])
if provisional:
out.append("")
out.extend(provisional)
if thin:
out.append(f"- (warming up, <{MIN_SAMPLES} clean samples: {', '.join(sorted(thin))})")
return "\n".join(out) + "\n"
def main() -> int:
ap = argparse.ArgumentParser()
ap.add_argument("--only", help="comma-separated node names")
ap.add_argument("--quiet", action="store_true", help="print only the report")
ap.add_argument("--show", action="store_true", help="print current baselines and exit")
ap.add_argument("--attempts", type=int, default=2,
help="extra attempts for a node that looks regressed (default 2)")
a = ap.parse_args()
if a.show:
print(json.dumps(baselines_from_history(), indent=2, sort_keys=True))
return 0
nodes = NODES
if a.only:
want = {s.strip() for s in a.only.split(",")}
nodes = [n for n in NODES if n[0] in want]
baselines = baselines_from_history()
self_ip = local_ip()
stamp = datetime.now(timezone.utc).astimezone().strftime("%Y-%m-%d %H:%M %Z")
results = []
for name, host, root in nodes:
if not a.quiet:
print(f" benching {name} ...", file=sys.stderr, flush=True)
results.append(run_node(name, host, root, self_ip))
# Adaptive retry: only a node that looks regressed pays for extra attempts. A busy
# neighbour is far more likely than a real regression, and best-of-attempts costs nothing
# when the node is idle — so the common case stays a single pass over the fleet.
for i, r in enumerate(results):
if not usable(r) or not compare([r], baselines):
continue
name, host, root = next(n for n in nodes if n[0] == r["node"])
if not a.quiet:
print(f" {name} looks off — {a.attempts} more attempt(s) ...", file=sys.stderr, flush=True)
results[i] = merge_best(
[r] + [run_node(name, host, root, self_ip) for _ in range(a.attempts)]
)
confirmed, provisional = confirm(compare(results, baselines))
with HISTORY.open("a") as fh:
for r in results:
fh.write(json.dumps({"ts": stamp, **r}) + "\n")
# Rewrite the derived view *after* appending, so it reflects this run too.
BASELINES.write_text(json.dumps(baselines_from_history(), indent=2, sort_keys=True) + "\n")
print(report(results, confirmed, provisional, baselines, stamp))
return 1 if any(x.startswith("[!]") for x in confirmed) else 0
if __name__ == "__main__":
os.chdir(HERE)
sys.exit(main())