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Scroll performance significantly degraded on iPhone X, Xs devices due to irregular input events delivery. #31086
Description
Myself and some others discussing in #22314 have noticed significant scroll performance issues on iPhone X,Xs devices with scrolling views.
Anecdotally it seems drag gestures are the main issue, while flings seem slightly better.
@coreysprague suggested it may be because these devices have a 120hz gesture sample rate (https://www.macworld.com/article/3235709/iphone-x-samples-touch-input-at-120hz-for-faster-smoother-response.html).
Just want to clarify that this does happen even when running in release mode.
Steps to Reproduce
Here's a tiny sample app where you can reproduce the scroll jitters and frame skips, just grab an iPhone X,Xs and run in release mode.
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
const padding = EdgeInsets.symmetric(vertical: 10, horizontal: 10);
return MaterialApp(
home: Scaffold(
body: ListView(
children: <Widget>[
Container(
margin: padding,
height: 200,
color: Colors.grey,
),
Container(
margin: padding,
height: 200,
color: Colors.orange,
),
Container(
margin: padding,
height: 200,
color: Colors.grey,
),
Container(
margin: padding,
height: 200,
color: Colors.orange,
),
Container(
margin: padding,
height: 200,
color: Colors.grey,
),
Container(
margin: padding,
height: 200,
color: Colors.orange,
),
Container(
margin: padding,
height: 200,
color: Colors.grey,
),
Container(
margin: padding,
height: 200,
color: Colors.orange,
),
],
),
),
);
}
}Logs
No errors in logs w/ flutter run --verbose
No issued found w/ flutter analyze
[✓] Flutter (Channel stable, v1.2.1, on Mac OS X 10.14.4 18E226, locale en-US)
• Flutter version 1.2.1 at /Users/dwempe/flutter
• Framework revision 8661d8a (8 weeks ago), 2019-02-14 19:19:53 -0800
• Engine revision 3757390
• Dart version 2.1.2 (build 2.1.2-dev.0.0 0a7dcf17eb)
[✓] Android toolchain - develop for Android devices (Android SDK version 28.0.3)
• Android SDK at /Users/dwempe/Library/Android/sdk
• Android NDK location not configured (optional; useful for native profiling support)
• Platform android-28, build-tools 28.0.3
• Java binary at: /Applications/Android Studio 2.app/Contents/jre/jdk/Contents/Home/bin/java
• Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1248-b01)
• All Android licenses accepted.
[✓] iOS toolchain - develop for iOS devices (Xcode 10.2)
• Xcode at /Applications/Xcode.app/Contents/Developer
• Xcode 10.2, Build version 10E125
• ios-deploy 1.9.4
• CocoaPods version 1.5.3
[✓] Android Studio (version 3.3)
• Android Studio at /Applications/Android Studio 2.app/Contents
• Flutter plugin version 34.0.1
• Dart plugin version 182.5215
• Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1248-b01)
[✓] VS Code (version 1.33.0)
• VS Code at /Applications/Visual Studio Code.app/Contents
• Flutter extension version 2.24.0
[✓] Connected device (2 available)
• Android SDK built for x86 • emulator-5554 • android-x86 • Android 8.0.0 (API 26)
(emulator)
• _________ iPhone • 00008020-000B25CE0298002E • ios • iOS 12.2
Metadata
Metadata
Assignees
Labels
Repeatedly frustrating issues with non-experimental functionalityRelates to speed or footprint issues (see "perf:" labels)Affects or could affect many people, though not necessarily a specific customer.Only manifests on certain devicesflutter/engine related. See also e: labels.Viewports, list views, slivers, etc.iOS applications specifically
Activity
bobmoff commentedon Apr 16, 2019
I tried the tiny sample app on my iPhone X and iPhone 5. I can verify that only on the iPhone X there are frequent stutters (lost frames) while drag-scrolling. As soon as I let go of the screen with finger and it only scrolls on inertia, it is fine.
There is also an increase of these stutters if I swipe up to app switch on iPhone X and then just taps the app again to resume it, and right when it has been resumed again I start drag scrolling. This might be related to this issue: #28113
xster commentedon Apr 25, 2019
Wild guess but we seem to have seen a similar issue in #6135 only during touch events. We may need to gate the incoming event flow.
liyuqian commentedon Apr 29, 2019
Thanks to @yunyu 's example app, I reproduced some stutters on iPhone X but not on iPhone 6S.
Attached is the trace with
--trace-skiaenabled (GPU thread frame time exceeds budget around 26.8s).dart-timeline-2019-3-29.json.zip
Considering that it only happened on iPhoneX but not iPhone6S, I think it's related with the GPU hardware and the OpenGL driver of iPhone X. My hope is that Skia's Metal backend will eventually solve this kind of problem. So far, I'm not sure how Flutter can fix this without Skia's help.
@bsalomon (Skia's GPU lead): can you see something suspicious from the trace? Does Skia currently run tests on iPhone X? I seem to only find iPhone 6/7 on perf.skia.org . I guess as iPhone X gets more market share, such performance issues will become more and more critical. Also note that this performance issue only happened during first launches or app switches. So any performance tests that did a lot of warm up repetitions may not catch it.
yunyu commentedon Apr 30, 2019
@liyuqian Just to note, this performance issue is also noticeable if you hold your finger down while scrolling (it doesn't occur when you fling by releasing your finger). Not sure if that is a separate issue.
tvolkert commentedon May 6, 2019
@yunyu if you're seeing this on the simulator, that's a different issue that happens when keeping the finger down on non-Flutter simulator apps too, like the Settings app.
yunyu commentedon May 6, 2019
@tvolkert I am seeing this on a physical device with the example app linked previously.
msw333 commentedon May 6, 2019
The effect is severe on iPhone X and minimal, but still observable, on iPad Pro (2. Gen.). Haven’t tested with other devices yet.
BTW: Mostly, the jittering is gone after 2-3 sec. But I even experienced times, where the jittering stays and can only be stopped with a restart of the app.
bsalomon commentedon May 6, 2019
Sorry for slow response, just got back from vacation. I took a look at the trace. There is a crazy amount of time being spent in GrRenderTargetOpList::onExecute (31ms in one frame) but there isn't enough tracing detail to know what is actually happening in there. We'd need more detailed tracing events to get a better idea of where the time is going.
Side note: it's probably not too early to start trying to integrate the Metal backend. We're at the point where it draws almost everything correctly and performance is approx equal to GL with low hanging fruit still left to pick.
1rgs commentedon May 9, 2019
@bsalomon what would be the best way to get more detailed tracing?
93 remaining items
derolf commentedon Sep 14, 2019
@liyuqian please see #40042 (reported by me) and #38293 (might be related).
Fix licenses
christian-muertz commentedon Sep 16, 2019
Seems to be fixed on master now
cbracken commentedon Sep 16, 2019
@liyuqian should this bug be re-closed?
liyuqian commentedon Sep 16, 2019
Yes, the relaneded fix in the framework since b9a34de . Closing this issue.
liyuqian commentedon Sep 20, 2019
Reopen for another revert...
volskaya commentedon Sep 22, 2019
I'm observing the same irregular input delivery and dropped events on Android OnePlus 7 Pro. Alleviated greatly with cherry picking #36616 , tho
Miss at most one frame for irregular scroll drag eventsis still an issue and is apparent even more so on its 90hz screen, as opposed to iPhone's 60hz.@derolf reports above that the jitters are gone, when screen recording. I observe the same, while the screen recorder is locked at 60fps.
liyuqian commentedon Sep 23, 2019
@volskaya : thank you for the report! I'm creating a new issue #41118 to track it separately.
liyuqian commentedon Sep 30, 2019
The fix has been relanded in 4891e4a . Hopefully it won't be reverted this time.
github-actions commentedon Aug 27, 2021
This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of
flutter doctor -vand a minimal reproduction of the issue.Smooth out iOS irregular input events delivery (flutter-team-archive/…