[Mesa-dev] [Bug 55998] Pretty huge slowdown in mesa 9.0

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=55998

--- Comment #22 from Fredrik Höglund <fredrik at kde.org> ---
(In reply to comment #19)
> e943e5c291c5f4c017f9f5a483f1940313333fc3 is the first bad commit
> commit e943e5c291c5f4c017f9f5a483f1940313333fc3
> Author: Chad Versace <chad.versace at linux.intel.com>
> Date:   Thu Aug 2 17:13:17 2012 -0700
> 
>     intel: Advertise multisample DRI2 configs on gen >= 6
> 
>     This turns on window system MSAA.
> 
> So in other words, it looks like KDE is using multisampling now, whereas it
> didn't before.  Our implementation of that may not be optimal, and may have
> bugs, but it will always be far slower than single sampling.
> 
> My next question would be: how can one disable the use of MSAA in KWin or
> Plasma?  I don't see an option for that, but I would be really surprised if
> there wasn't one...

The algorithm that chooses the FBConfig doesn't check the values of GLX_SAMPLES
and GLX_SAMPLE_BUFFERS, so I guess it ends up picking an MSAA config purely by
accident. That's something we'll have to fix in KWin.

But unfortunately that also means that there is no way to enable or disable the
use of MSAA right now.

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