[meta-freescale] imx6q gpu performance lower than expected

[Dmitriy B.]

2015-03-17 17:08 GMT+03:00 Nikita Yushchenko <nyushchenko at dev.rtsoft.ru>:

> Hi
>
> I've built freescale community bsp dizzy for a custom imx6q based board,
> and now I'm experimenting with GPU performance under Qt5.
>
> I have both xcb and eglfs backends running (under different builds).
>
> However performance is lower than was expected: on LVDS 1280x800,
> Qt5_CinematicExperience shows about 35-37 FPS, both under X11 and under
> eglfs. If using smaller window under X11, FPS increases, if using
> 1920x1080 it goes down to 20.
>
> This is much smaller than people get [1].
>
> [1] https://community.freescale.com/thread/305066
>
>
Please, read the original post on the forum, it says that resolution of
that demo is 1024x768 https://community.freescale.com/thread/305066#336263
You trying to run 1920x1080, what did you expect? As Otavio suggests, this
might be connected to memory, calculate the memory bandwidth needed for
drawing your app under X.org and I bet you'll hit the limit.


> CPU in both cases (x11 and egl) is almost unloaded (30% of one core
> under eglfs, 30+30 under X11) so looks like speed limiting comes from GPU.
>
> What could be reason for this?  Any hints?


Hint: Vivante X11 GPU drivers use DRI1(one, the 1998 one) and need a asm
patch to libdrm to work. Guess what happens when you drag 90s technology to
latest X.org on an embedded device.


> TIA,
> Nikita Yushchenko
> --
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Best Regards,
Dmitriy Beykun
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