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

[Rune Kjær Svendsen]

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
> >
>
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