[Mesa-dev] [PATCH 00/25] i915 HW context support

[Kenneth Graunke]

On 06/04/2012 10:53 PM, Dave Airlie wrote:
>>
>> I've run these on various workloads and saw nothing worth mentioning.
> 
> Nothing at all? no speedups, slowdowns, etc
> 
> why should we merge all this code then :-)
> 
> Dave.

Preserving hardware state across batches is going to be necessary for:

* Transform feedback in the presence of geometry shaders

  Right now, Mesa counts the number of primitives emitted on the CPU,
  relies on the kernel resetting the register to 0, and offset values
  in software.  With GS, we obviously can't count primitives on the CPU.

* Primitive restart in hardware

and seems to be increasingly necessary for new features as we move
forward.  So we'd like to get it in place; we can cut more state uploads
and tune Mesa further once it's there.