[gdal-dev] Re: Strange things with gdalwarp ...

[Greg Coats]

On Aug 22, 2009, at 4:51 AM, Hermann Peifer wrote:

> Just to repeat my earlier observations: over the last days, I tried  
> with all kinds of -wm and GDAL_CACHEMAX settings, and also added  
> the options TILED=YES and SKIP_NOSOURCE=YES. I haven't documented  
> the performance changes systematically, but my overall impression  
> was that the changes were rather small. I also tried -multi on my  
> dual processor machine, but I ended up with a fatal error.


In January 2009, working with GDAL version 1.6.0, I did some testing  
and documenting of the effect of GDAL_CACHEMAX. Using as input an  
uncompressed GeoTif 15,000 x 15,000 x 3 = 675 MB, organized into 1024  
x 1024 tiles, I found that using gdal_translate to convert this  
GeoTif to a GeoJP2 with the default --config GDAL_CACHEMAX 40 took  
10473 sec (= 175 minutes), but increasing GDAL_CACHEMAX by only 12.5%  
to --config GDAL_CACHEMAX 45 the processing took only 166 sec (= 2.7  
minutes), which is 63 times faster! Further tests showed that  
increasing --config GDAL_CACHEMAX to values greater than 45 (up to  
1800) did not effect processing time. Greg

GDAL 1.6.0, released 2008/12/04
Input GeoTif 15,000 x 15,000 x 3 = 675 MB
gdal_translate -of JP2KAK -co QUALITY=10 --config GDAL_CACHEMAX
0040  10473.14 sec
0041  10326.75 sec
0042  10492.85 sec
0043   7081.57 sec
0044   3503.33 sec
0045    166.23 sec
0050    166.31 sec
0055    165.89 sec
0060    165.78 sec
0080    165.48 sec
0100    166.53 sec
0125    165.59 sec
0150    165.72 sec
0200    165.65 sec
0250    166.58 sec
0300    166.13 sec
0350    166.59 sec
0400    166.06 sec
0600    166.00 sec
0800    165.10 sec
1000    165.25 sec
1200    165.94 sec
1400    165.43 sec
1600    165.56 sec
1800    166.31 sec

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