Frank,<br><br>Thanks for the recommendation of adding --config GDAL_CACHEMAX 500 -wm 500 to the gdalwarp command.<br><br>With --config GDAL_CACHEMAX 500 -wm 500 added to gdalwarp the speed of mosaicing 6 tiles creating a mosaic of 3 gb on a server with 4 gb of RAM increased the gdalwarp speed by 25%.
<br><br>I then tried --config GDAL_CACHEMAX 625 -wm 625 instead of --config GDAL_CACHEMAX 500 -wm 500 and I got the following error:<br>Out of memory allocatint 400042260 byte destination buffer<br><br>If the RAM was increased beyond 4 GB then I would be able to increase to GDAL_CACHEMAX 625 -wm 625 and beyond, but you don't believe that above 500 will have any effect on gdalwarp performance. Correct?
<br><br>Thanks,<br><br>John Mitchell<br><br><div><span class="gmail_quote">On 7/13/07, <b class="gmail_sendername">Frank Warmerdam</b> <<a href="mailto:warmerdam@pobox.com">warmerdam@pobox.com</a>> wrote:</span><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
John Mitchell wrote:<br>> Hi,<br>><br>> Will increasing the RAM on a server increase the speed of gdalwarp?<br>><br>> If I have a server that currently has 4 gigs of RAM and I increase the<br>> RAM to say 75 gigs will I notice a difference in the speed of processing
<br>> a 75 gig image via gdalwarp?<br><br>John,<br><br>What commandline options are you using with gdalwarp? By default<br>gdalwarp won't take much advantage of your 4GB of existing RAM.<br><br>You might want to try setting the -wm flag. For example "-wm 500" will
<br>operate on 500MB chunks at a time which is better than the default.<br>Increasing the io block cache size may also help. This can be done<br>on the command like:<br><br>gdalwarp --config GDAL_CACHEMAX 500 -wm 500 ...
<br><br>This uses 500MB of RAM for read/write caching, and 500MB of RAM for<br>working buffers during the warp. Beyond that I'm doubtful more<br>memory will make a substantial difference.<br><br>Best regards,<br>--<br>
---------------------------------------+--------------------------------------<br>I set the clouds in motion - turn up | Frank Warmerdam, <a href="mailto:warmerdam@pobox.com">warmerdam@pobox.com</a><br>light and sound - activate the windows |
<a href="http://pobox.com/~warmerdam">http://pobox.com/~warmerdam</a><br>and watch the world go round - Rush | President OSGeo, <a href="http://osgeo.org">http://osgeo.org</a><br><br></blockquote></div><br><br clear="all">
<br>-- <br>John J. Mitchell