[x264-devel] Optimization of the x264

[jogging song]

On 10/9/07, Gabriel Bouvigne <gabriel.bouvigne at joost.com> wrote:
>
> Victor Mateevitsi a écrit :
>
> > x264_macroblock_cache_load
> > x264_macroblock_cache_save
> > x264_macroblock_analyse
> >
> > Reading cache_load, I realized that there is a struct named cache, that
> > stores the cached data.
> > Why not use pointers in this struct, without having to copy the data
> > from one struct to the other ?
> > I think we will gain some FPS there.
>
> The purpose is to have "compact" data within the CPU cache. If your
> source data was already within the CPU cache, copy will be very fast
> (assuming there is still available space within the cache). If your
> source data was not already within CPU cache, you will have a slower
> copy, but future access will be fast. By using pointers, you would have
> to use a lot of CPU prefetch hints in order to avoid being stalled
> because of a cache miss during computing-intensive parts.



But using cache data structure, access to the cache is through x264_scan8,
which requires a lot of address calculation.


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