[plug] NVidia drivers and RENDER acceleration

[Craig Ringer]

Hi folks

I just ran into this one, and thought I'd post a note in case others 
didn't know:

/usr/share/doc/NVIDIA_GLX-1.0/README

         Option "RenderAccel" "boolean"
               Enable or disable hardware acceleration of the RENDER
               extension.  THIS OPTION IS EXPERIMENTAL. ENABLE IT AT YOUR
               OWN RISK.  There is no correctness test suite for the
               RENDER extension so NVIDIA can not verify that RENDER
               acceleration works correctly.   Default: hardware
               acceleration of the RENDER extension is disabled.

In other words, RENDER acceleration is disabled by default on the NVidia 
cards. I could've sworn this wasn't in the README of the older (probably 
_much_ older) versions, either. I don't know about you folk, but I know 
that I heard the NVidia drivers supported hardware-accelerated RENDER 
and assumed it would be running. I then wondered why my text display was 
so apallingly slow in any app that used freetype/xft2.

Well, that's why - it doesn't use the acceleration. Enabling it (by adding
	Option	"RenderAccel" "true"
to my Device section in XF86Config) has massively sped up my desktop. I 
strongly suggest that others try it out - bearing in mind the warnings 
about it in the above README snippet, of course.

Yeah, you could say I'm posting a RTFM revelation. I think it matters, 
because many people say that the NVidia drivers support RENDER accel but 
it's never mentioned that it's disabled by default. Additionally, I've 
seen enough comments around the place to show that I'm not the only one 
wondering why anti-aliased text is so apallingly slow even when 
"accelerated".

So ... have fun :-)

For the record, I'm using:
01:00.0 VGA compatible controller: nVidia Corporation NV28 [GeForce4 Ti 
4200 AGP 8x] (rev a1)
Class 0300: 10de:0281

and it seems to work great for me. Woo ... I can remove the 'export 
GDK_USE_XFT=0' in /usr/local/mozilla/mozilla now :-)

Craig Ringer

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