Wave-2 PW1's exit criterion, and the instrument it needed.
VAAPI and direct NVENC both log a PUNKTFUNK_PERF submit split. PyroWave did not — which meant the
single encoder the GPU-priority work exists to defend was the one you could not put a number on.
Adds per-frame timing of the synchronous encode (whole `submit`: CSC + encode + fence wait +
packetize, which for this backend IS the encode), summarised every 2 s as mean/p50/p99/max.
p99 rather than mean-only on purpose. The failure patch 0005 describes is a TAIL event — frames
going ~2 ms to 15-18 ms at 95 % game load while the mean barely moves — so a mean-only readout
would report "fine" straight through the thing being measured.
WHAT IT MEASURED — .21, RTX 5070 Ti (610.57.04), GRID 2 benchmark loop saturating the GPU at
54-87 %, PyroWave 1080p, same binary both arms (only CAP_SYS_NICE differs), 30-frame windows with
the warm-up window dropped:
arm p50 p99 worst frame
default priority (refused) ~2.6 ms ~6.4 ms 9.5 ms
REALTIME granted ~3.2 ms ~4.4 ms 5.4 ms
REALTIME granted (repeat) ~3.35 ms ~4.8 ms 5.1 ms
p99 down ~30 %, worst frame roughly halved, for ~0.6 ms on the median. For a streaming encoder
that is the right side of the trade — the tail is what becomes a visible hitch.
This CONTRADICTS the patch's only prior datum (RTX 4090 / Windows / WDDM: "did not reduce the
spikes"), so patch 0005's header now records the Linux/NVIDIA result beside it, with an explicit
"do NOT delete this patch on the strength of the WDDM result — the two stacks disagree". Header
prose only; the diff hunks stay byte-identical and `git diff crates/pyrowave-sys/vendor/` is
untouched by this commit.
Caveats recorded rather than buried: the arms were not interleaved and the game load drifted
between them, capture was frame-starved (~2.5 fps) so this is encode latency under contention and
not a full-rate stream, and it is two granted runs against one refused run. The direction held
across all 25 windows.
Also worth knowing for anyone repeating this: `encode_fps` is a VACUOUS metric on this rig. A
headless gamescope with no real content emits ~12 fps, so both arms simply report the capture rate.
Measure latency, not throughput.
Gates green at CI parity.
enricobuehler
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