Greg Pomerantz
ed52109dba
Root cause of scroll jank: first-present of each Image uploaded pixels
inside the render frame (~11-30 ms per 400px texture, 1.3 visible
hitches/s at 120 Hz; grey-image A/B: 20 -> 1). Slint has no render
thread and no pre-upload API.
Fix: decode worker creates the Rgba8Unorm texture on Slint's own wgpu
device (captured from GraphicsAPI::WGPU30 at RenderingSetup) and submits
the async upload; UI wraps it in Image::try_from(tex). Zero pixel work
in the render frame. CPU from_rgba8 fallback retained.
Measured (Pixel 9 Pro 120 Hz, 400 px, per-frame FR hook):
before: >10ms renders 20 in 15s (max 30 ms), 3 borderline 8-9 ms
after: 0 mid-scroll renders > 4.4 ms (median 1.9, p95 2.9);
only post-idle first-frames expensive (invisible)
Also: FR per-frame logging via set_rendering_notifier; APLY timestamp.
93 lines
3.6 KiB
Bash
Executable File
93 lines
3.6 KiB
Bash
Executable File
#!/usr/bin/env bash
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# One-shot jank A/B for the phone (usage: ADB_SERIAL=10.0.0.5:5555 ./scripts/jank_ab.sh)
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#
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# What it does:
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# 1. Installs the release APK (build with ./scripts/build.sh aarch64 first).
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# 2. Verifies thread priorities (thumb-* at nice 2, slint vsync at 0).
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# 3. Runs TWO 30-second scroll windows — real textures, then grey 1x1
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# images — with logcat capture + cadence analysis in between.
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# THE USER MUST SCROLL WITH A FINGER during each window
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# (moderate drag, no fling — the reported repro).
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# 4. Prints a comparison: % of scroll events on the 8.3 ms grid,
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# stall count (gap > 16 ms), worst gaps.
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#
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# Interpretation:
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# real janky + grey smooth -> texture/GPU path is the culprit
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# both janky -> base render/present/event path
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# both smooth -> the priority fix worked; ship it
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set -u
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E="adb ${ADB_SERIAL:+-s $ADB_SERIAL}"
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APK=target/release/apk/gallery.apk
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PKG=wow.gmp.gallery
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CMD=/sdcard/Download/.gallery_cmd
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GREY=/sdcard/Download/.gallery_grey
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PERF=/sdcard/Download/.gallery_perf.log
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[ -f "$APK" ] || { echo "build first: ./scripts/build.sh aarch64"; exit 1; }
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scroll_window() { # $1 = label, $2 = tag, $3 = seconds
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local out="/tmp/jank_$2.txt"
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$E shell "echo -n '' > $PERF" 2>/dev/null || true
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echo "### $1 — scroll now (moderate drag, no fling)..."
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sleep "$3"
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$E pull "$PERF" "$out" >/dev/null 2>&1
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python3 - "$out" << 'EOF'
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import re, sys
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ev = []
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for line in open(sys.argv[1], errors="ignore"):
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m = re.match(r"SCR +([\d.]+)", line)
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if m: ev.append(float(m.group(1)))
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if len(ev) < 10:
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print(f" {sys.argv[1]}: only {len(ev)} scroll events — not enough data"); sys.exit()
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gaps = [ev[i+1]-ev[i] for i in range(len(ev)-1)]
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# drop the first gap (window edge) and any multi-event same-ms catch-ups
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# are kept — they ARE the jank signature
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gaps = gaps[1:]
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on_grid = sum(1 for g in gaps if 6.5 <= g <= 10.5)
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stalls = [g for g in gaps if g > 16]
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import collections
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buckets = collections.Counter()
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for g in sorted(stalls): buckets['16-25' if g<25 else '25-40' if g<40 else '40-65' if g<65 else '>65'] += 1
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print(f" events={len(ev)} on ~8ms grid={100*on_grid/len(gaps):.0f}% "
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f"stalls(>16ms)={len(stalls)} p95={sorted(gaps)[int(len(gaps)*0.95)]:.1f}ms "
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f"worst={max(gaps):.1f}ms stall buckets: {dict(buckets)}")
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# tick-stall context: how many TICK stalls, any APLY nearby
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EOF
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echo " TICK-stall lines: $(grep -c '^TICK' $out 2>/dev/null) APLY lines: $(grep -c '^APLY' $out 2>/dev/null)"
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}
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check_prios() {
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local pid; pid=$($E shell pidof $PKG)
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echo "### thread priorities (pid $pid)"
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$E shell "for t in /proc/$pid/task/*; do c=\$(cat \$t/comm 2>/dev/null); case \$c in slint*|thumb*) n=\$(awk -F')' '{print \$2}' \$t/stat | awk '{print \$17}'); echo \" \$c nice=\$n\";; esac; done"
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}
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install_and_start() { # $1 = "grey" to enable the grey knob before launch
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$E install -r "$APK" >/dev/null
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if [ "${1:-}" = grey ]; then $E shell "touch $GREY"; else $E shell "rm -f $GREY"; fi
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$E shell am force-stop $PKG
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$E shell am start -n $PKG/android.app.NativeActivity >/dev/null
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sleep 8
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}
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echo "=== installing $APK ==="
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install_and_start
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check_prios
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echo
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echo "=== window 1: REAL textures (30 s) ==="
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scroll_window "real" real 30
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echo
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echo "=== restarting with grey 1x1 images ==="
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install_and_start grey
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check_prios
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echo
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echo "=== window 2: GREY images (30 s) ==="
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$E logcat -d 2>/dev/null | grep "grey images ON" || echo " WARNING: grey knob not active!"
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scroll_window "grey" grey 30
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$E shell "rm -f $GREY $CMD"
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echo
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echo "done. Compare the two summaries above."
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echo " (raw captures: /tmp/jank_real.txt /tmp/jank_grey.txt)"
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