[Mesa-dev] glxgears is faster but 3D render is so slow

Brian Paul brianp at vmware.com
Wed Mar 13 07:21:57 PDT 2013

On 03/13/2013 04:11 AM, jupiter wrote:
> Hi Brian,
> Sorry for not being clear, let me clarify it.
> On 3/13/13, Brian Paul<brianp at vmware.com>  wrote:
>> Well, the Xlib/swrast driver does everything in software, unlike a DRI
>> driver which does most things with the GPU.  Xlib will always be slower.
> My local test machine graphic card does not have hardware
> acceleration, it does not support OpenGL, it does not have NVIDIA. I
> guess the DRI driver may still implement software GL even though it
> might access some basic functions of the low budget graphic card, but
> correct me, if I am using wrong terminology.

Yes, swrast may also be used via DRI, when there's no DRI driver for 
the hardware GPU or when the hardware driver needs a software fallback.

>> The gallium llvmpipe driver should be quite a bit faster.
>> Just install LLVM first, then reconfigure/rebuild Mesa, set your
>> LD_LIBRARY_PATH to the lib/gallium/ directory and you should get llvmpipe.
> Yes, I have already built the Mesalib with LLVM, I posted the
> configuration in my last email, let me post it again.
> ${SOURCE}/${CONFIGURE} --prefix=${INSTALL} --enable-xlib-glx
> --disable-dri --enable-gallium-llvm --with-llvm-shared-libs
> It did not produce a faster result, it was virtually not much
> differences when I run Chimera comparing to use of
> --with-gallium-drivers=swrast unless my configuration is wrong. Please
> let me know a correct version of configuration for llvmpipe. The
> libdrm version is 2.4.42. The libllvm version is 3.2.

libdrm is irrelevant for llvmpipe.

> I can also use a test program to measure Mesa in different drivers if
> you could let me know which test program can be used for benchmarking
> the Mesalib using different drivers of swrast, or llvm or DRI? And
> where is the test program source code I can download from?

The Mesa demos git tree can be cloned per 

> Please also see attached glxinfo for Mesa llvm.

The key line is "OpenGL renderer string: Mesa X11".  That's not 
llvmpipe.  If you're really using llvmpipe it should say something 
like "OpenGL renderer string: Gallium 0.4 on llvmpipe (LLVM 3.2, 128 

Perhaps your LD_LIBRARY_PATH env is pointing at the wrong libGL.so


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