[Interest] Rotating objects in QML are killing performance

[Michael Andersen]

I found the root of the problem: there is something fishy with Nvidia's
sync to vblank implementation. If Vsync is turned off, everything works ok,
if it is turned on then all hell breaks loose. I just downloaded and
installed their latest drivers (310.44) and the problem still exists there.

So, sorry for the noise, it seems Nvidia is to blame. Unfortunately Vsync
was on to fix a different Nvidia bug, so now I have to choose the lesser of
the two :/ I am reminded of Linus's outburst at Nvidia last year.. feeling
pretty annoyed right now.



On 12 April 2013 23:07, Michael Andersen <michael at steelcode.com> wrote:

> I was in the process of filing a bug when I discovered a bunch more
> things, some of them make me strongly feel like the blame doesn't lie with
> Qt at all.
>
> On my desktop, which is an Ubuntu 12.10 box with an Nvidia 560 Ti,
> Nvidia's binary drivers version 304.51:
> - While the application is running, dragging *any window, even ones not
> belonging to the Qt app* or touching any unity menu also lags and stutters.
> - Running glxgears or tux racer causes the same system-wide problems: high
> cpu usage for X process, every other GUI application grinds to a halt if
> you touch it.
>
> On my laptop which is also Ubuntu 12.10, a Radeon HD 7600M and fglrx
> version 4.2.11903: no problem. Nothing. Smooth as anything.
>
> It would be great to see if an Nvidia card with the nouveau drivers had
> this problem or not, either way I don't think this is something that Qt can
> solve - and I have no control over where my app is deployed. I wonder how
> minecraft does not have this problem though - perhaps there *is* a way.
>
> Cheers
> Michael
>
>
> On 12 April 2013 12:50, Michael Andersen <michael at steelcode.com> wrote:
>
>>
>>>
>>>
>>>>
>>>> 846cf1a13f80fe4590cc9ad4d9972d7a173accd6 to QtBase, which is going into
>>>> 5.1, resize issues on gnome for instance.
>>>>
>>>
>>> I will grab the 5.1 alpha and see if the behaviour still exists.
>>>
>>>
>>
>> Not that I _really_ expected things to be different, but the problem
>> still exists on 5.1.
>>
>> As the app runs and drags smoothly if there are no animations, I might
>> just make a workaround that freezes all the animations when the window is
>> dragged. I'm assuming I can find signals for that kind of thing. I don't
>> suppose there is some central point where I can freeze all animations and
>> transitions?
>>
>
>
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