Greg Pomerantz 2f4768f354 Fix 120Hz scroll jank end-to-end: render-ahead present + full-cache eviction off the UI thread

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).

2026-10-30 02:49:23 -04:00

3.5 KiB

Raw Blame History

Slint Royalty-free Desktop, Mobile, and Web Applications License

Version 2.0

Preamble

Slint is a toolkit that can be used to build user interfaces for applications. Slint (hereafter referred to as Software) is made available under different licenses by SixtyFPS GmbH incorporated at Oranienburger Str. 44, 16540 Hohen Neuendorf, Germany (SixtyFPS). The Slint Royalty-free Desktop, Mobile, and Web Applications License is suitable for those who develop desktop, mobile, or web applications and do not want to use open source components under copyleft licenses.

1. Grant of Rights

SixtyFPS hereby grants You a world-wide, royalty-free, non-exclusive license to use, reproduce, make available, modify, display, perform, distribute the Software as part of a Desktop, Mobile, or Web Application.

A Desktop Application is a computer program that is designed to run on a general-purpose computer (PC or notebook), typically installed and executed locally on the computer's operating system.

A Mobile Application is a computer program that is designed to run on a general-purpose mobile computer (mobile phone or tablet), typically installed and executed locally on the computer's operating system.

A Web Application is a computer program that is designed to run in the sandbox environment provided by a web browser.

Desktop Application, Mobile Application, and Web Application are hereafter referred to as Application.

2. License Conditions - Attribution

You may distribute the Software as part of an Application, modified or unmodified, provided that You do either of the following:

(a) Display the AboutSlint widget in an "About" screen or dialog that is accessible from the top level menu of the Application. In the absence of such a screen or dialog, display the widget in the "Splash Screen" of the Application.

(b) Display the Slint attribution badge on a public webpage, preferably where the binaries of your Application can be downloaded from, in such a way that it can be easily found by any visitor to that page.

3. Limitations

The License does not permit to distribute or make the Software publicly available alone and without integration into an Application. For this purpose you may use the Software under the GNU General Public License, version 3.

The License does not permit the use of the Software within Embedded Systems. An Embedded System is a computer system designed to perform a specific task within a larger mechanical or electrical system.

The License does not permit the distribution of Application that exposes the APIs, in part or in total, of the Software.

You may not remove or alter any license notices (including copyright notices, disclaimers of warranty, or limitations of liability) contained within the source code form of the Software.

4. Warranty and Liability

SixtyFPS is only liable for conflicting rights of third parties if SixtyFPS was aware of these rights without informing you. Unless required by applicable law or agreed to in writing, SixtyFPS provides the Software on an "as is" basis, without warranties or conditions of any kind, either express or implied, including, without limitation, any warranties or conditions of merchantability, or fitness for a particular purpose.

Unless required by law, SixtyFPS won't be liable for any direct, indirect, incidental, or consequential damages arising in any way out of the use of the Software.

3.5 KiB Raw Blame History