Re: threading in mesa

Hi Brian,

> Be aware that the llvmpipe driver does not work with the OSMesa 
> interface. 
:-(

that's no fun. In general, I would really like to be using llvmpipe 
driver. If I'm reading mesa docs correctly it's the only one that 
supports threading and provides glsl. I'm using osmesa without x on 
systems like cray xe, 24 cores per node, and sgi uv 1000 1024 cores. 
Soon we'll also be using an intel mic cluster, each card will have 60 
cores with 2 hardware threads, and 2 hyper threads. I would expect that 
the threaded driver would make a big difference on these systems.

Is there any info on the performance or scaling of the threaded llvmpipe 
driver?

Thanks again
Burlen

On 12/07/2012 03:45 PM, Brian Paul wrote:
> On 12/07/2012 11:00 AM, burlen wrote:
>> Hi,
>>
>> I'd like to use a threaded mesa build with the osmesa driver on an
>> Intel MIC. I'm exploring the possibility of it's native mode to avoid
>> having to make modifications to mesa sources. A number of comments in
>> the docs suggest this may not be easily achieved.
>
> I doubt auto-threading of osmesa/swrast will yield much improvement 
> there.
>
>
>> Is threading limited to 8, web docs state this but it seems low given
>> recently the increasing core counts?
>> Does threading depend on LLVM compilers? I think for something like
>> MIC in native mode intel compilers would be necessary.
>
> You're talking about the llvmpipe driver?  If so, I think you could 
> increase LP_MAX_THREADS to something larger than 8.  Never tried it 
> though.  Be aware that the llvmpipe driver does not work with the 
> OSMesa interface.
>
>
>> Those are my initial concerns, also curious to know if the MIC
>> architecture is on Mesa developers radar?
>
> I don't recall any discussion of MIC so far.
>
> -Brian