Greg Pomerantz
2f4768f354
Three root causes, all fixed and verified on the Pixel 9 Pro: 1. Present phase (backend + renderer): VSYNC_LOCKED_RENDER defers the render to the vsync wake; RENDER_AHEAD presents the previous frame at the start of render() (phase = wake + ~1.1 ms) and holds the new frame one slot. Crash fix: a held wgpu frame must be PRESENTED, never merely dropped, before the next acquire (AlreadyAcquired panic at launch otherwise); discard_pending_frame presents too. 2. Full-res prefetch churn (src/lib.rs): the 8-slot full cache cycled through a ~20-cell viewport forever (137 decodes/20 s) and each eviction free()'d a 50 MB Vec on the UI thread (20-52 ms CPU spikes, ~7/s = the residual SLOWEV NonMain jank). Fix: 60 s tombstone cooldown on evicted paths (idle prefetch skips, urgent tap bypasses) + off-thread reaper for the freed blobs (insert: 21 ms -> 4 us). 3. (earlier) Skia final flush + Mailbox present mode (vendor, M3). Instrumentation (all behind --features perf): OTHR/INVK/INVK_TAG/FLCK lines for cross-thread closure timing and push-site tagging. Warm measured swipe, 8580-file grid: cadence median 8.33 ms (exact 120 Hz), p99 15.5 ms, 5/552 gaps >16.7 ms (0.9%, max 28.3 ms, zero >33 ms); PRES phase median ~994 us, zero late frames. Docs updated (docs/BUGS/scroll-jank-120hz.md, full scorecard + line reference). Also: vendored i-slint-core + wgpu-hal (vkshim interposition patch), vkshim profiling tooling, backend made a non-optional dep, debuggable flag for simpleperf (REMOVE before shipping).
51 lines
1.1 KiB
WebGPU Shading Language
51 lines
1.1 KiB
WebGPU Shading Language
struct Globals {
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mvp: mat4x4<f32>,
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size: vec2<f32>,
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_pad0: u32,
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_pad1: u32,
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};
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struct Locals {
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position: vec2<f32>,
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velocity: vec2<f32>,
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color: u32,
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_pad0: u32,
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_pad1: u32,
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_pad2: u32,
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};
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@group(0)
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@binding(0)
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var<uniform> globals: Globals;
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@group(1)
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@binding(0)
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var<uniform> locals: Locals;
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struct VertexOutput {
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@builtin(position) position: vec4<f32>,
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@location(0) tex_coords: vec2<f32>,
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@location(1) color: vec4<f32>,
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};
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@vertex
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fn vs_main(@builtin(vertex_index) vi: u32) -> VertexOutput {
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let tc = vec2<f32>(f32(vi & 1u), 0.5 * f32(vi & 2u));
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let offset = vec2<f32>(tc.x * globals.size.x, tc.y * globals.size.y);
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let pos = globals.mvp * vec4<f32>(locals.position + offset, 0.0, 1.0);
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let color = vec4<f32>((vec4<u32>(locals.color) >> vec4<u32>(0u, 8u, 16u, 24u)) & vec4<u32>(255u)) / 255.0;
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return VertexOutput(pos, tc, color);
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}
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@group(0)
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@binding(1)
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var tex: texture_2d<f32>;
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@group(0)
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@binding(2)
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var sam: sampler;
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@fragment
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fn fs_main(vertex: VertexOutput) -> @location(0) vec4<f32> {
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return vertex.color * textureSampleLevel(tex, sam, vertex.tex_coords, 0.0);
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}
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