[Development] QT_XCB_NATIVE_PAINTING makes worse that without of it
annulen at yandex.ru
Fri Mar 22 17:23:00 CET 2019
22.03.2019, 19:08, "Allan Sandfeld Jensen" <kde at carewolf.com>:
> On Freitag, 22. März 2019 12:46:59 CET Denis Shienkov wrote:
>> Hi guys.
>> I have iMX6 board with Qt 5.11.2 and Qt-widgets based application. I have
>> compiled my Qt with an 'xcb_native_painting' option.
>> I was hoping that this would speed up my UI and reduce the load on the CPU,
>> but I was greatly mistaken:
>> When the QT_XCB_NATIVE_PAINTING is not set, I got following top:
>> * Xorg: 3.6 %
>> * app: 12.8 %
>> When the QT_XCB_NATIVE_PAINTING is *set*, I got following top:
>> * Xorg: 23 %
>> * app: 4.5 %
>> What? QT_XCB_NATIVE_PAINTING makes it worse in 2x-times... WTF?
> Sounds like XCB isn't as well optimized as Qt is ;)
> Note though, that there are number of techniques to make the native painting
> faster, such as always using qpixmap so the images stays buffered on the
> server side. You might be able to massage your program to be faster with
> native painting, but the whole reason for switching to Qt side painting was
> that for the average application developer Qt side was faster.
Native painting should be most beneficial when using remote X11
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