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

[Rune Kjær Svendsen]

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.

Med venlig hilsen,

Rune Kjær Svendsen
Østerbrogade 111, 3. - 302
2100 København Ø
Tlf.: 2835 0726


On Mon, Mar 11, 2013 at 12:52 PM, Rune Kjær Svendsen <runesvend at gmail.com>wrote:

> 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?
>
> /Rune
>
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