[Mesa-dev] i965: disable_throttling

[Eero Tamminen]

Hi,

On 09.06.2017 09:21, Marathe, Yogesh wrote:
> I’m looking forward to set this brw->disable_throttling to true, I’m
> actually observing adverse effect on performance benchmarks after I
> force set that to true. What’s the expectation from disable_throttling
> here?

By default Mesa throttles its buffer swaps so that compositor is able to 
easier insert its own batches to better place in GPU batch queue.

If throttling is disabled, compositor needs to discard more frames as 
obsolete, because benchmark is running too many frames forward of it.

Normally having no throttling means that:
* composited performance looks worse to the user, because only some of 
the rendered frames end up on screen
* benchmark runs faster because compositor composes less frames, i.e. 
takes less of the system bandwidth


 > BTW, this is on android.

On TDP constrained machines, power management can do funky things.  When 
in doubt, use fixed GPU & CPU speeds are re-test.



	- Eero