While copying, ft-eyegrab woke every 300 us (about 1,500 to 3,000 times a second) and
fingerprinted all eight slots each time: 8 x 256 strided reads from DMA-BUF memory.
- Each look now checks only the slot each camera writes next. The order is known (camera 0
3,0,1,2; camera 1 7,5,4,6,5,7,6,4), and the next slot follows from the last two; the table
starts from those orders and learns from every frame, so a SteamVR update that changes
them costs a few seconds of full scans, not frames.
- A camera with nothing in its expected slot 1.5 frames after its last one, or with no
order yet, gets all four slots checked, as before. A frame that turns up in an unexpected
slot means full scans for that camera for 2 s.
- A slot's fingerprint is taken again when it stops being one of the two in use, so a later
check sees only a new frame. A frame is still passed on when its camera starts the frame
after next.
- Between frames it sleeps until 2.5 ms before the next is due, then looks every 1 ms, with
0.5 ms of timer slack (PR_SET_TIMERSLACK, --share only). With no frames from either
camera for 0.5 s (headset off) it looks every 4 ms.
- --rec keeps its 0.3 ms polls (and the expected-slot checks), for its timestamps.
Tested offline by building poll_frames against simulated cameras that write each frame in
four bursts, the last after the next frame starts (6 s, both cameras): 1,076 frames passed
on, none torn or skipped, with the known orders and with camera 1 in a different order.
Wakeups 1,486/s -> 207/s, the poller's CPU 3.6% -> 0.8% of a core (in plain memory; the real
DMA-BUF reads cost more), and a frame's start is seen 1.35 ms after it begins on average
instead of 0.76. With a camera stalling 15 ms every 2 s, the old poller passed on 22 torn
frames and the new one 8 or fewer.
Built (glibc 2.38 symbols at most, the host has 2.39), not installed: it runs as root from
/etc/frametop, so it takes effect only after gaze/tracker/install.sh (sudo).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
ft-eyes looked for new frames about 1,000 times a second: each pass of its loop asked the
control socket with a non-blocking recvfrom (a BlockingIOError nearly every time), read
both cameras' counters, and slept 1 ms. The frames come every 11.1 ms per camera, and only
as counters in ft-eyegrab's shared memory, so there's no fd to wait on.
Now each pass ends in select() on the control socket, with a timeout until 2 ms before the
next frame of either camera is due (from when its last one was seen), then every 1 ms until
it comes. A command wakes it at once. A camera with no frame for 0.1 s (headset off,
grabber idle) isn't waited for, and with both stopped it looks every 20 ms. Waiting for the
frame grabber's file uses the same select, 0.2 s at a time, instead of sleeping through
commands.
A new frame is still seen within about 1 ms of when it lands. On a synthetic share at 90 Hz
per camera, on a heavily loaded headset (load average 23, so ft-eyes rarely sat idle), its
waits went from 178 to 81 a second; unloaded, the old loop's 1 ms sleeps add up to about
1,000.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
ft-eyes and ft-gaze run in the dev container through distrobox, so they live in podman's
libpod scope: frametop-gaze.service's limits never reach them, and they ran at nice 0
next to vrcompositor and vrserver, also at nice 0.
- ft-eyes sets itself to nice 10 and SCHED_BATCH at start, before its threads. Batch
turns off wakeup preemption, so a frame ft-eyes wakes up for can wait out a running
compositor's turn; a few ms late costs the gaze little.
- ft-gaze sets nice 5 before its threads start, but stays SCHED_OTHER: each sample goes
on to the pointer, and batch would add the same wait to every one of them.
- Both only ever lower their priority (a higher nice already set wins), and a failure
is logged and ignored. Checked in the dev container: nice 0 -> 10, policy 0 -> 3
(SCHED_BATCH) without any capability.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Nothing called cv2.setNumThreads, so OpenCV kept a pool of one worker per core for
pupil windows of 140 to 240 px. Live, its idle workers spun and yielded about 14,000
times a second each, about a quarter of a core, next to SteamVR's compositor. numpy's
OpenBLAS also started 8 threads that never had work.
eyes_pupil.py now sets OpenCV to one thread, and ft-eyes sets OPENBLAS_NUM_THREADS and
OMP_NUM_THREADS to 1 before numpy loads (a value already in the environment wins).
Replaying fit1 into a scratch share (ft-eyes-replay, 14 s measured, capped at one core
with the replay): threads 13 -> 1, involuntary context switches 3,812/s -> 430/s,
system time 6.9% -> 1.6% of a core. Under that cap the frames it kept up with went from
21-36 to 57-69 a second per eye.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
A user on a fresh install got "Calibration failed: only 0 of 21 dots" with
no reason. The installer never installed our tracker, so gaze used
SteamVR's, and the only way SteamVR's tracker rejects a dot is losing an
eye for most of the look. The panel just showed a red ring.
- install.sh: step 9/10 installs our tracker (gaze/tracker/install.sh)
after gaze mode, yes by default; it needs sudo, so --yes runs it only
when sudo won't prompt. If it fails, gaze keeps SteamVR's tracker.
Configs that still say GAZE_TRACKER=steam (the old template) are asked
whether to switch.
- GAZE_TRACKER=auto, the new default: ours when it's installed (the
frame grabber, its unit, and ft-eyes' Python), else SteamVR's.
ft-gazed rechecks every second, so installing it switches over. Input
Settings lists Own tracker first as recommended, and says how to
install it when it's missing (checking the host's /etc through
/run/host from the dev container).
- The calibration panel has a note line, orange over the instructions:
why a dot wasn't taken (an eye lost, a blink, the eyes disagreeing for
SteamVR's tracker, from steady_samples' new drop counts; ft-eyes' reply
for ours), what a click is still waiting for after 1.5 s, and a failed
calibration's most common reason, which the Gaze page shows too.
steady_samples keeps the same samples as before (checked on 2037
windows of recordings); a lost eye is named before a blink, since its
openness reads 0.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
- frame_sudo (scripts/_env.sh) replaces three copies of sudo_run. On
the Frame it asks in the terminal even when stdin isn't one, which
install.sh's steps never had: saying yes to the Bluetooth fixes or
hand tracking stopped the install with "no terminal for sudo".
From a PC it asks through ssh -t when .env has no password.
- start_with_steamvr: the pointer, power, and gaze services restart
when SteamVR runs (a re-install runs the new code) and are left to
start with it when it doesn't, instead of failing the install.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
- gaze/tracker/lab/eyes_track.py: nothing used it
- Input Settings: the pointer role backend, whose page was removed
- ft-screens: no log line for every floating-window resize
- hands: ft-hands --help gives the palm-down default (1: off), the
uninstall removes ft-handsctl's link, .frame-job is ignored
- Display Settings: "Save as profile…", not "Save current arrangement"
- two stale comments (ft-pointer's grabprobe, ft-gaze)
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
frame-eyes, a separate project until now, becomes gaze/tracker:
- ft-eyegrab (was fe-bufprobe) copies the eye-camera frames, read-only, out of
SteamVR's eyetracking process. It runs as the system service
frametop-eyegrab.service, which gaze/tracker/install.sh installs to
/etc/frametop with sudo. It keeps only CAP_SYS_PTRACE, CAP_DAC_READ_SEARCH, and
CAP_CHOWN, and copies frames only while /dev/shm/frametop-eyes-want is fresh,
holding none of the tracker's buffers otherwise.
- ft-eyes (was fe-trackd) runs under ft-gazed in the dev container, with
build/venv's pinned numpy and OpenCV: while Eye tracker is Own tracker, or on
the probe's lease ("eyes SECONDS"). No sudo password or fe-live script at
run time any more.
- lab/ holds the research tools (ft-eyes-score, -e2e, -record, -replay,
-session) and findings.md. Recordings live outside the repo, in
~/.local/share/frametop/eyes/captures; .gitignore catches stray frame dumps.
Its socket is now @ft_eyes, its output /dev/shm/frametop-eyes-gaze, and its state
~/.local/state/frametop/gaze/eyes. On practice1 -> practice2 the whole live path
(ft-eyes-e2e) gives 1.30 deg median and 3.18 for the worst tenth, as before the
move (1.30, 3.21).
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
