Bug 1762879

Summary:	QtWayland applications lag for 100ms with backingstore warnings
Product:	[Fedora] Fedora	Reporter:	John Brooks <john>
Component:	qt5-qtwayland	Assignee:	Lubomir Rintel <lkundrak>
Status:	CLOSED ERRATA	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	31	CC:	jgrulich, jreznik, kde-sig, lkundrak, pierluigi.fiorini, rdieter, than
Target Milestone:	---
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:	qt5-qtwayland-5.12.5-2.fc30 qt5-qtwayland-5.12.5-2.fc31	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2019-10-27 01:08:56 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description John Brooks 2019-10-17 18:01:24 UTC

Description of problem:
With wayland on Fedora 31, QtQuick applications often emit the warning:

qt.qpa.wayland.backingstore: Delivering update request through fallback timer, may not be in sync with display

This is related to a 100ms freeze in rendering, often at the start of animations, which is very visible as a performance issue. An upstream fix is merged for 5.13; see https://bugreports.qt.io/browse/QTBUG-76813. I do not know if it will be backported to 5.12, but the commit 9f5b9622 applies cleanly.

Version-Release number of selected component (if applicable):
5.12.5, 5.13.1

How reproducible:
Reproducible for all QtQuick applications. Could also apply to other applications.

Steps to Reproduce:
See upstream bug and testcase.

Actual results:
Prints backingstore warning, visible lag at the start of animations.

Expected results:
Smooth, perfectly smooth.

Comment 1 Fedora Update System 2019-10-18 09:13:40 UTC

FEDORA-2019-8bcfa667d4 has been submitted as an update to Fedora 31. https://bodhi.fedoraproject.org/updates/FEDORA-2019-8bcfa667d4

Comment 2 Fedora Update System 2019-10-18 09:13:40 UTC

FEDORA-2019-4f26ba5d4a has been submitted as an update to Fedora 30. https://bodhi.fedoraproject.org/updates/FEDORA-2019-4f26ba5d4a

Comment 3 Fedora Update System 2019-10-18 17:36:02 UTC

qt5-qtwayland-5.12.5-2.fc31 has been pushed to the Fedora 31 testing repository. If problems still persist, please make note of it in this bug report.
See https://fedoraproject.org/wiki/QA:Updates_Testing for
instructions on how to install test updates.
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2019-8bcfa667d4

Comment 4 Fedora Update System 2019-10-18 21:00:20 UTC

qt5-qtwayland-5.12.5-2.fc30 has been pushed to the Fedora 30 testing repository. If problems still persist, please make note of it in this bug report.
See https://fedoraproject.org/wiki/QA:Updates_Testing for
instructions on how to install test updates.
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2019-4f26ba5d4a

Comment 5 Fedora Update System 2019-10-27 01:08:56 UTC

qt5-qtwayland-5.12.5-2.fc30 has been pushed to the Fedora 30 stable repository. If problems still persist, please make note of it in this bug report.

Comment 6 Fedora Update System 2019-10-27 01:29:36 UTC

qt5-qtwayland-5.12.5-2.fc31 has been pushed to the Fedora 31 stable repository. If problems still persist, please make note of it in this bug report.