On 12/01/17 13:53, Pierre Ossman wrote:
> For small updates I see performance growing logarithmically, measured in
> pixels/second. At around 500k pixels it starts leveling off at ~1.5
> Gpixels/second. After that the performance starts dropping linearly as
> the update grows.

I'll answer myself here...

This seems to be a CPU cache issue. Below this limit I see:

         4,469,985      cache-misses:u            #    0.336 % of all cache 
    35,279,259,258      instructions:u            #    1.70  insn per cycle     

Above the limit I get:

       194,571,782      cache-misses:u            #   30.322 % of all cache 
    18,084,891,734      instructions:u            #    0.73  insn per cycle     

So no wonder things take a turn for the worse.

I'll have to think a bit on how to make this more efficient. Ideas are always 

Pierre Ossman           Software Development
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A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
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