Re: [Gegl-developer] VIPS and GEGL performance and memory usage comparison

[jcupitt gmail com]

Hello all, vips maintainer here, thank you for this interesting discussion.

On 29 January 2016 at 16:37, Daniel Rogers <daniel phasevelocity org> wrote:
> A fast 8 bit pipeline is great for previews or single operation stacks, or
> when accuracy is not as important for the user.

My feeling is that gegl is probably right to be float-only, the cost
is surprisingly low on modern machines. On my laptop, for that
benchmark in 8-bit I see:

  $ time ./vips8.py tmp/x.tif tmp/x2.tif
  real    0m0.504s
  user    0m1.548s
  sys    0m0.104s

If I add "cast(float)" just after the load, and "cast(uchar)" just
before the write, the whole thing runs as float and I see:

  $ time ./vips8.py tmp/x.tif tmp/x2.tif
  real    0m0.578s
  user    0m1.768s
  sys    0m0.148s

Plus float-only makes an opencl path much simpler.

As you say, this tiny benchmark is very focused on batch performance,
so fast startup / shutdown and lots of file IO. It's not what gegl is
generally used for.

John