[Pixman] [PATCH 2/4] Added fast path for "pad" type repeats

[Søren Sandmann]

Ben Avison <bavison at riscosopen.org> writes:

>>> That's a speedup of 3.86x.
>>
>> Impressive. On IVB, I'm only seeing an improvement of 42.6 -> 34.8s
>> with the full firefox-chalkboard trace, which is marginally better than
>> just implementing PAD support for the simple fetcher. How does that
>> compare with the tiled approach?
>
> I suspect it depends upon the source image size and how much padding
> there is. With tiled repeats of course, you still have to fetch the
> source buffer again for every tile. For pad repeats, just the extreme
> left/right pixel needs to be fetched for each row, and the entire repeat
> region then only needs to fetch the destination buffer. With large
> amounts of horizontal padding, as the trimmed firefox-chalkboard trace
> uses, that's got to help pipelining.
>
> Maybe the full firefox-chalkboard trace uses a lower proportion of pad
> repeats with large horizontal extents?

I pushed the first patch to master. For this one, did you try comparing
Chris' patch to your on ARMv6? Also, did we ever find out whether it was
a bug in Firefox. I'm still somewhat skeptical that it's intended for a
PAD image to be accessed so far out of bounds.


Søren