[Mesa-dev] Very low framerate when recording desktop content in Weston using mesa git on Radeon 5770 (glReadPixels slow path)

[Marek Olšák]

Slowness is not usually a bug.

I guess it can be optimized even more. It depends on where the
bottleneck is now.

Marek

On Sun, Mar 17, 2013 at 10:14 PM, Rune Kjær Svendsen
<runesvend at gmail.com> wrote:
> Thank you very much! This is much better. It's gone from 0.5-ish FPS when
> zooming in to around 10 FPS, depending on screen content.
>
> So I figure this isn't a bug? I assumed it was a bug, but is the case simply
> that an efficient glReadPixels path for radeon/gallium doesn't exist?
>
> The patch set sure helps in that regard, although it'd be really nice to get
> 30 FPS consistently, if at all possible.
>
> Thanks again.
>
> /Rune
>
>
> On Sun, Mar 17, 2013 at 6:46 PM, Andreas Boll <andreas.boll.dev at gmail.com>
> wrote:
>>
>> 2013/3/17 Rune Kjær Svendsen <runesvend at gmail.com>:
>> > Hello list
>> >
>> > I'm having problems recording the desktop content using the Weston
>> > compositor's built-in recording function. When I start a recording and
>> > do
>> > something that changes a lot of screen content (like zooming in on the
>> > desktop, for example), I get around 0.5 FPS. Using sysprof, I can see
>> > that
>> > ~98% of CPU is used in the function unpack_XRGB8888(). krh has told me
>> > this
>> > is caused by glReadPixels going through a slowpath. I have a Radeon HD
>> > 5770
>> > GPU and I'm using mesa git (I've tried the mesa version in the Ubuntu
>> > 12.10
>> > repos, and the xorg-edgers PPA, same result).
>> >
>> > Does anyone know what the issue could be, or how to debug the problem
>> > further?
>> >
>>
>> This patch series [1] should help. You might want to try it.
>>
>> [1] http://lists.freedesktop.org/archives/mesa-dev/2013-March/036214.html
>>
>> > Doing some debugging, it seems the call to ctx->Driver.ReadPixels() in
>> > _mesa_ReadnPixelsARB leads to _mesa_readpixels() being called in
>> > readpix.c.
>> >
>> > I'm attaching some output of gdb that will hopefully be useful.
>> >
>> > I'm also attaching the debug terminal output of running Weston with the
>> > DRM
>> > backend.
>> >
>> > Let me know if I can provide other useful information.
>> >
>> > _______________________________________________
>> > mesa-dev mailing list
>> > mesa-dev at lists.freedesktop.org
>> > http://lists.freedesktop.org/mailman/listinfo/mesa-dev
>> >
>
>
>
> _______________________________________________
> mesa-dev mailing list
> mesa-dev at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/mesa-dev
>