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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#1F497D;mso-fareast-language:EN-US">Issues opened:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="font-family:Symbol"><span style="mso-list:Ignore">·<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]>#3630 <a href="https://github.com/OSGeo/gdal/issues/3630">
<code><span style="font-size:10.0pt">gdalwarp -multi</span></code> should auto-enable GDAL_NUM_THREADS=ALL_CPUS
</a><o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="font-family:Symbol"><span style="mso-list:Ignore">·<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]>#3631 <a href="https://github.com/OSGeo/gdal/issues/3631">
gdalwarp error "Failed to acquire WarpMutex in WarpRegion()"</a> <o:p></o:p></p>
<p class="MsoListParagraph" style="text-indent:-18.0pt;mso-list:l0 level1 lfo1"><![if !supportLists]><span style="font-family:Symbol"><span style="mso-list:Ignore">·<span style="font:7.0pt "Times New Roman"">
</span></span></span><![endif]>#3632 <a href="https://github.com/OSGeo/gdal/issues/3632">
gdalwarp <code><span style="font-size:10.0pt">mode</span></code> resample much more expensive than needed</a>
<o:p></o:p></p>
<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span lang="EN-US" style="font-size:11.0pt;font-family:"Arial",sans-serif;color:#1F497D">-Matt<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#1F497D;mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif">From:</span></b><span lang="EN-US" style="font-size:11.0pt;font-family:"Calibri",sans-serif"> Even Rouault <even.rouault@spatialys.com>
<br>
<b>Sent:</b> March 31, 2021 10:27 AM<br>
<b>To:</b> Matt.Wilkie <Matt.Wilkie@yukon.ca>; gdal-dev@lists.osgeo.org<br>
<b>Subject:</b> Re: [gdal-dev] More info on gdalwarp resampling methods?<o:p></o:p></span></p>
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<pre><strong><span style="font-family:"Courier New";color:black">*** External email: Do not click on links or attachments except from trusted senders. ***<o:p></o:p></span></strong></pre>
<pre><strong><span style="font-family:"Courier New";color:black">******************************************************************************************</span></strong><span style="color:black"><o:p></o:p></span></pre>
<pre><span style="color:black"><br><br><o:p></o:p></span></pre>
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<p>Matt,<o:p></o:p></p>
<p>I see that in the -multi mode, the I/O threads waits for a maximum of 10 minutes for the computation thread to have finished. And you likely hit that limit because of the large value of -wm you set. There's no reason we max at 10 minutes however. Please
find a but about that, including my analysis.<o:p></o:p></p>
<p>For better speed, I'd suggest you add --config GDAL_NUM_THREADS ALL_CPUS (or a given number of threads). The -multi switch only does one thread for I/O and one thread for computation. By adding --config GDAL_NUM_THREADS xxx you'll also multi-thread the computation
part. The gain of -multi alone is generally neglectable. We should probably make -multi turn on --config GDAL_NUM_THREADS ALL_CPUS as well.<o:p></o:p></p>
<p>I also see that the mode resampling spend an awful lot of time on line "memset(panVals, 0, nBins*sizeof(int));" where nBins=65536 on Int16 data, and that for each output pixel. We could probably do something much less expensive for most cases. Please file
a separate enhancement ticket about that particular case.<o:p></o:p></p>
<p>Even<o:p></o:p></p>
<p><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-size:10.0pt">Le 31/03/2021 à 18:46, <a href="mailto:Matt.Wilkie@yukon.ca">
Matt.Wilkie@yukon.ca</a> a écrit :<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:10.0pt;font-family:Consolas;color:#1F497D;mso-fareast-language:EN-US">gdalwarp --config GDAL_CACHEMAX 4096 -wm 512 -multi -co TILED=YES -co COMPRESS=ZSTD -t_srs EPSG:3579 -r mode -co predictor=2 tri_mergedDEM_clipped_16bit.tif
tri_mergedDEM_clipped_16bit_ytalb-rs-mode.tif </span><span style="font-size:10.0pt"><o:p></o:p></span></p>
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<pre>-- <o:p></o:p></pre>
<pre><a href="https://imsva91-ctp.trendmicro.com:443/wis/clicktime/v1/query?url=http%3a%2f%2fwww.spatialys.com&umid=682B3DEE-BED8-6F05-8639-74A30E43DC88&auth=c132af8ee7c9d1278d61a701569070a095ce962e-453104e8853fb736505949aed5860b4e74f3ecf8">http://www.spatialys.com</a><o:p></o:p></pre>
<pre>My software is free, but my time generally not.<o:p></o:p></pre>
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