High CPU usage with basic QML animation

pvaibhav

Hello,

I was seeing bad performance and high cpu usage in my QML based apps, as much as 50-100% on iOS (device or simulator), and even desktop. After optimising my code as much as I could, I decided to write the simplest possible animated app to isolate the root cause.

Strangely, even with just a rotating label, I still get 17-20% cpu usage consistently. My ObjC based native iOS app which rotates a png image barely registers above 1% cpu usage. There isn't much code (see below) to profile, and I am not able to make sense of tracing the compiled app using Instruments.

Any help will be appreciated.

Code below:

import QtQuick 2.5
import QtQuick.Window 2.2

Window {
    visible: true

    MouseArea {
        anchors.fill: parent
        onClicked: {
            Qt.quit();
        }
    }

    Text {
        text: qsTr("Hello World")
        anchors.centerIn: parent
        NumberAnimation on rotation {
            from: 0
            to: 360
            duration: 4000
            loops: Animation.Infinite
        }
    }
}

drunkwolfs

I have the same problem.
Help.

ratijas

Years later, CPU usage of animations is still a problem. Getting 70% CPU wasted on rotating Shape and animating its PathAngleArc's startAngle and sweepAngle.

ndias

Hi @ratijas ,
I don't get significant high CPU values running at least simple animations. Can you provide a sample code and some clarifications about your setup?
I'am using PySide (Python Qt binding) on my side. I have never tried using QML with C++.

JoeCFD

I created a small test case to display a GIF file and it uses about 10%CPU. The root cause is that it runs too fast?
If a loop over call of a func which does almost nothing can use a lot of CPU.

hamer

Here is a bug report: https://bugreports.qt.io/browse/QTBUG-99525
Please vote/watch it if you face the same problem.