[Mesa-users] llvmpipe os mesa with my own llvm

[Brian Paul]

On 05/22/2013 04:40 PM, Burlen Loring wrote:
> On 5/22/2013 9:02 AM, Brian Paul wrote:
>> On 05/21/2013 04:43 PM, Burlen Loring wrote:
>>> I have recently built and installed llvmpipe os mesa using my own llvm
>>> build on a new server. Using my regression tests I've observed that
>>> varying LP_NUM_THREADS has no affect on performance with this build, but
>>> it had a dramatic affect on my workstation (60 sec w/ 1 thread down to
>>> 11 sec w/16 threads).  The threading performance should be even better
>>> on the new server since it has vastly better cpu's each with 8 physical
>>> cores vs the old 4 core cpus on my workstation. Also comparing outputs
>>> of run on my workstation and the server this pixels are ~40% different,
>>> but the result looks pretty close to the eye.
>>>
>>>   I'm wondering what can explain the pixel difference and also the
>>> performance difference?  Could it be that I'm not really using the
>>> llvmpipe driver? or llvm JIT compilation for my shaders? I am sure
>>> lvvmpipe and osmesa tracker is built and installed but I'm at a loss has
>>> to debug further. setting GALLIUM_PRINT_OPTIONS does nothing. Any advice
>>> greatly appreciated.
>>
>> As a first step you can call/print glGetString(GL_RENDERER) to verify
>> that you're using llvmpipe.  I'm assuming this is your own app.
>>
>> -Brian
>>
>
> OK so far so good
>
> 1010: GL_VENDOR: VMware, Inc.
> 1010: GL_VERSION: 2.1 Mesa 9.2.0 (git-1e88d14)
> 1010: GL_RENDERER: Gallium 0.4 on llvmpipe (LLVM 3.2, 256 bits)

As for the 40% different pixels, could you post a couple small 
screenshots to compare?  Do you know if the difference comes from 
texturing or complex fragment shaders, etc?

Not sure what to say about the performance difference.  If the app is 
dominated by vertex transformation, then varying LP_NUM_THREADS might 
not make a lot of difference.

Have you compared other Mesa demos or apps to see how they behave?

-Brian