I even have created a simple test app, which re-fill the 1280x800 rect every 50 msec with the 'red' and 'green' colors.
[code] #include <QApplication> #include <QWidget> #include <QPaintEvent> #include <QPainter> class Widget final : public QWidget { public: explicit Widget(QWidget *parent = nullptr); private: void paintEvent(QPaintEvent *event) final; void timerEvent(QTimerEvent *event) final; }; Widget::Widget(QWidget *parent) : QWidget(parent) { startTimer(50); } void Widget::paintEvent(QPaintEvent *event) { QPainter p(this); static bool toggled = false; const auto color = (toggled) ? QColor(Qt::red) : QColor(Qt::green); const auto rect = event->rect(); p.fillRect(rect, color); toggled = !toggled; } void Widget::timerEvent(QTimerEvent *event) { Q_UNUSED(event); update(); } int main(int argc, char *argv[]) { QApplication app(argc, argv); Widget w; w.setMinimumSize(1280, 800); w.show(); return app.exec(); } [/code] And then I see that the Desktop PC has the ~0% CPU load, but the iMX6 has ~50% CPU load. WTF? BR, Denis ср, 29 авг. 2018 г. в 12:39, Denis Shienkov <denis.shien...@gmail.com>: > Hi all. > > I have an Apalis iMX6 board with the Yocto's image with the working > 'eglfs' and 'linuxfb' backends (without of X11 support). > > I need to create a 'pure' QtWidgets application, where I need to use a > real-time plotting with the Qwt library (using the Qt Quick is not an > option, as there the QtCharts is not ready for usage) . > > But, I'm sadly surprised that a 2D painting takes ~100% CPU loading as > with the 'eglfs' and as with 'linuxfb' backends. It is not an acceptable, > because, e.g. on Desktop Linux/Windows it takes ~4-5% CPU loading. > > Is any workarounds for this? Maybe I need to re-build the Yocto's image to > enable the X11 'xcb' support? > > BR, > Denis > > >
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