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Re: [libcvd-members] SubImages no longer need to be distinct from BasicI


From: Georg Klein
Subject: Re: [libcvd-members] SubImages no longer need to be distinct from BasicImages.
Date: Wed, 29 Oct 2008 15:34:28 +0000

gcc version 4.1.2 20070925 (Red Hat 4.1.2-33)

forloop 8.26731  (494985830000)
imageref 9.94063  (494985830000)
basicimage_iterator 6.41841  (494985830000)
subimage_iterator 8.32609  (494985830000)
subimage_iterator_fastend 8.35848  (494985830000)
subimage_iterator_stl 8.34101  (494985830000)
basicimage_iterator_stl 6.43227  (494985830000)

Reducing image size to 20x20 & boosting iterations:
forloop 3.21801  (197090000000)
imageref 4.22899  (197090000000)
basicimage_iterator 2.28253  (197090000000)
subimage_iterator 3.39948  (197090000000)
subimage_iterator_fastend 4.62725  (197090000000)
subimage_iterator_stl 4.89984  (197090000000)
basicimage_iterator_stl 2.2789  (197090000000)

core 2 2.66, -march=core2 -O3

I've not yet used the subimage functionality so don't really mind what
happens to it.

On Wed, Oct 29, 2008 at 3:13 PM, E. Rosten <address@hidden> wrote:
> SubImages were originally distinct from BasicImages for speed, since
> BasicImages used raw pointers for iterators, and SubImage iterators were
> somewhat more complex.
>
> Here are the timing results for a simple function (summing up all pixels in
> an image):
>
>
> forloop 16.3304  (494985830000)
> imageref 20.2895  (494985830000)
> basicimage_iterator 16.7697  (494985830000)
> subimage_iterator 16.4321  (494985830000)
> subimage_iterator_fastend 17.8282  (494985830000)
> subimage_iterator_stl 16.2188  (494985830000)
> basicimage_iterator_stl 16.4601  (494985830000)
>
> Interesting points:
>
> ImageRef scanning is no longer 10x slower than other methods
>
> pointers are slower than more complex iterators.
>
> The fastend speed hack is now a slowness hack.
>
> The STL is faster than the hand coded algorithm.
>
> gcc version 4.3.1 20080507 (prerelease)
>
> CPU is:
>
> cpu family      : 15
> model           : 3
> model name      : Intel(R) Pentium(R) 4 CPU 3.20GHz
> stepping        : 4
> cpu MHz         : 3207.370
> cache size      : 1024 KB
>
>
> Anyone else want to check these results?
[...]




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