some iterator benchmarks

[C. Boemann]

Hi

I did the iterator benchmarks and tried it with varying tilesizes

The findings are that for the nConseqHPixels type iterations the speed 
advantage of doubling the tilesize is a doubling of the speed
But for non nConseqHPixels the adavantage is only 2%
And for the random accessor the advantage is 25% 12% 10% (for each doubling 
the gain becomes smaller)

The disadvantages of doubling the tilesize is that it quadrouples the memory 
usaga every time a tile is committed to the undo buffer. Even in the best case 
assumption that would be very noticable in practical usage maybe not 4 times 
more but even 2 times more would be bad.

We could I guess only double the width giving us the speed but not the height 
lessening the memory impact. That would give us non-square tiles but other 
than possibly some undetected bugs i don't think it would be a problem.

normal (64px) tilesize
----------------------
QDEBUG : KisIteratorBenchmark::runBenchmark() HLineIterator run  0 took 307
QDEBUG : KisIteratorBenchmark::runBenchmark() qttest(6462) 
KisIteratorBenchmark::hLineIter: HLineIterator with nConseqHPixels run  0 took 
29
QDEBUG : KisIteratorBenchmark::runBenchmark() const HLineIterator took 272
QDEBUG : KisIteratorBenchmark::runBenchmark() HLineIteratorNG run  0 took 291
QDEBUG : KisIteratorBenchmark::runBenchmark() qttest(6462) 
KisIteratorBenchmark::hLineIterNG: HLineIterator with nConseqHPixels run  0 
took 29
QDEBUG : KisIteratorBenchmark::runBenchmark() const HLineIteratorNG took 272
QDEBUG : KisIteratorBenchmark::runBenchmark() VLineIterator run  0  took 292
QDEBUG : KisIteratorBenchmark::runBenchmark() const VLineIterator took 274
QDEBUG : KisIteratorBenchmark::runBenchmark() VLineIteratorNG run  0  took 292
QDEBUG : KisIteratorBenchmark::runBenchmark() const VLineIteratorNG took 284
QDEBUG : KisIteratorBenchmark::runBenchmark() RectIterator run  0 took 266
QDEBUG : KisIteratorBenchmark::runBenchmark() RandomIterator run  0  took 703
QDEBUG : KisIteratorBenchmark::runBenchmark() const RandomIterator took 704


128px tilesize
--------------
QDEBUG : KisIteratorBenchmark::runBenchmark() HLineIterator run  0 took 296
QDEBUG : KisIteratorBenchmark::runBenchmark() qttest(9424) 
KisIteratorBenchmark::hLineIter: HLineIterator with nConseqHPixels run  0 took 
14
QDEBUG : KisIteratorBenchmark::runBenchmark() const HLineIterator took 265
QDEBUG : KisIteratorBenchmark::runBenchmark() HLineIteratorNG run  0 took 277
QDEBUG : KisIteratorBenchmark::runBenchmark() qttest(9424) 
KisIteratorBenchmark::hLineIterNG: HLineIterator with nConseqHPixels run  0 
took 13
QDEBUG : KisIteratorBenchmark::runBenchmark() const HLineIteratorNG took 265
QDEBUG : KisIteratorBenchmark::runBenchmark() VLineIterator run  0  took 277
QDEBUG : KisIteratorBenchmark::runBenchmark() const VLineIterator took 265
QDEBUG : KisIteratorBenchmark::runBenchmark() VLineIteratorNG run  0  took 278
QDEBUG : KisIteratorBenchmark::runBenchmark() const VLineIteratorNG took 266
QDEBUG : KisIteratorBenchmark::runBenchmark() RectIterator run  0 took 240
QDEBUG : KisIteratorBenchmark::runBenchmark() RandomIterator run  0  took 527
QDEBUG : KisIteratorBenchmark::runBenchmark() const RandomIterator took 504


256px tilesize
--------------
QDEBUG : KisIteratorBenchmark::runBenchmark() HLineIterator run  0 took 284
QDEBUG : KisIteratorBenchmark::runBenchmark() qttest(12250) 
KisIteratorBenchmark::hLineIter: HLineIterator with nConseqHPixels run  0 took 
6
QDEBUG : KisIteratorBenchmark::runBenchmark() const HLineIterator took 260
QDEBUG : KisIteratorBenchmark::runBenchmark() HLineIteratorNG run  0 took 280
QDEBUG : KisIteratorBenchmark::runBenchmark() qttest(12250) 
KisIteratorBenchmark::hLineIterNG: HLineIterator with nConseqHPixels run  0 
took 7
QDEBUG : KisIteratorBenchmark::runBenchmark() const HLineIteratorNG took 261
QDEBUG : KisIteratorBenchmark::runBenchmark() VLineIterator run  0  took 290
QDEBUG : KisIteratorBenchmark::runBenchmark() const VLineIterator took 262
QDEBUG : KisIteratorBenchmark::runBenchmark() VLineIteratorNG run  0  took 277
QDEBUG : KisIteratorBenchmark::runBenchmark() const VLineIteratorNG took 261
QDEBUG : KisIteratorBenchmark::runBenchmark() RectIterator run  0 took 238
QDEBUG : KisIteratorBenchmark::runBenchmark() RandomIterator run  0  took 458
QDEBUG : KisIteratorBenchmark::runBenchmark() const RandomIterator took 440



512px tilesize
---------------
QDEBUG : KisIteratorBenchmark::runBenchmark() HLineIterator run  0 took 297
QDEBUG : KisIteratorBenchmark::runBenchmark() qttest(15419) 
KisIteratorBenchmark::hLineIter: HLineIterator with nConseqHPixels run  0 took 
4
QDEBUG : KisIteratorBenchmark::runBenchmark() const HLineIterator took 270
QDEBUG : KisIteratorBenchmark::runBenchmark() HLineIteratorNG run  0 took 279
QDEBUG : KisIteratorBenchmark::runBenchmark() qttest(15419) 
KisIteratorBenchmark::hLineIterNG: HLineIterator with nConseqHPixels run  0 
took 3
QDEBUG : KisIteratorBenchmark::runBenchmark() const HLineIteratorNG took 266
QDEBUG : KisIteratorBenchmark::runBenchmark() VLineIterator run  0  took 277
QDEBUG : KisIteratorBenchmark::runBenchmark() const VLineIterator took 263
QDEBUG : KisIteratorBenchmark::runBenchmark() VLineIteratorNG run  0  took 275
QDEBUG : KisIteratorBenchmark::runBenchmark() const VLineIteratorNG took 259
QDEBUG : KisIteratorBenchmark::runBenchmark() RectIterator run  0 took 238
QDEBUG : KisIteratorBenchmark::runBenchmark() RandomIterator run  0  took 425
QDEBUG : KisIteratorBenchmark::runBenchmark() const RandomIterator took 410