[Mesa-dev] [PATCH] ra: Disable round-robin strategy for optimistically colorable nodes.

[Francisco Jerez]

Matt Turner <mattst88 at gmail.com> writes:

> On Mon, Feb 16, 2015 at 10:40 AM, Francisco Jerez <currojerez at riseup.net> wrote:
>> My intuition is that the huge performance improvement Matt observed by
>> disabling the third scheduling heuristic is more likely to have been
>> caused by a decrease in the amount of cache thrashing caused by the fact
>> that he was running less channels concurrently rather than by the
>> scheduling heuristic itself.  Matt, did you rule out that possibility?
>
> Actually, the fragment shader used in the demo [1] doesn't can't
> register allocate in SIMD16 at all.
>
> From my Dec/Jan status report:
>
>> As an aside, I did an experiment to see what would happen if we used
>> SCHEDULE_PRE and spilled anyway (I added a couple of extra instructions
>> to increase register pressure over the threshold). I changed the window
>> size to 2048x2048 and rendered 1000 frames.
>>
>> SCHEDULE_PRE with no spills: 17.5 seconds to render 1000 fames
>> SCHEDULE_PRE with 4 spills (8 sends): 17.5 seconds
>> SCHEDULE_PRE_NON_LIFO with no spills: 28 seconds
>
> The demo does no texturing (no send instructions at all if no
> spilling), so it's not affected by caching as far as I understand.
>
> [1] https://github.com/ashima/webgl-noise

Ahh, yes, that makes sense to me too.
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