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).
40 lines
1.2 KiB
Rust
40 lines
1.2 KiB
Rust
// Copyright © SixtyFPS GmbH <info@slint.dev>
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// SPDX-License-Identifier: GPL-3.0-only OR LicenseRef-Slint-Royalty-free-2.0 OR LicenseRef-Slint-Software-3.0
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#[derive(Copy, Clone, PartialEq, Eq, Debug)]
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pub enum BreakOpportunity {
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Allowed,
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Mandatory,
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}
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#[derive(Clone)]
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pub struct LineBreakIterator<'a> {
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it: core::str::CharIndices<'a>,
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}
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impl<'a> LineBreakIterator<'a> {
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pub fn new(text: &'a str) -> Self {
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Self { it: text.char_indices() }
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}
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}
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impl<'a> Iterator for LineBreakIterator<'a> {
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type Item = (usize, BreakOpportunity);
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fn next(&mut self) -> Option<Self::Item> {
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for (byte_offset, char) in self.it.by_ref() {
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let maybe_opportunity = match char {
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'\u{2028}' | '\u{2029}' => Some(BreakOpportunity::Mandatory), // unicode line- and paragraph separators
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'\n' => Some(BreakOpportunity::Mandatory), // ascii line break
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_ if char.is_ascii_whitespace() => Some(BreakOpportunity::Allowed),
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_ => None,
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};
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if let Some(opportunity) = maybe_opportunity {
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return Some((byte_offset + 1, opportunity));
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}
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}
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None
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}
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}
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