Le mardi 15 mars 2011 22:48:16, Kyle Ellison a écrit : > Even, > > I tried out the patch. I was unable to actually try it in the 1.9 source > since my environment uses the C# bindings and gdal18.dll. So, I applied > the patch manually to the 1.8 version I had. That was not terribly > difficult... mainly just different line numbers in geotiff.cpp. Anyway, > we got the performance of yesteryear back. I would very much like you to > commit that change to the main trunk if that is possible. Thanks for your > help on this.
Would you mind opening a GDAL Trac ticket to record this ? Thanks > > Best Regards, > Kyle > > -----Original Message----- > From: Even Rouault [mailto:[email protected]] > Sent: Monday, March 14, 2011 5:41 PM > To: [email protected] > Cc: Kyle Ellison > Subject: Re: [gdal-dev] Many files over the network > > Kyle, > > you didn't mention which driver was in question. I guess this is GeoTIFF ? > I've looked at the code of the driver and it appears that it loads the .rpb > and .imd files at least since GDAL 1.6.0. The new thing in GDAL 1.8.0 is > that it also tries to load the _rpc.txt file. Is it that small difference > which causes the slowdown you observe ? > > In fact, setting GDAL_DISABLE_READDIR_ON_OPEN = TRUE might make things > actually worse (w.r.t to that aspect of loading rpb/rpc/imd) since the > driver has to really test the filesystem to look for the existence of the > files, whereas by default it would rely on the papszSiblingsFile list. > > Anyway, I've attached a patch (against SVN trunk) that differs the loading > of RPC and IMD until necessary (that is to say when GetMetadata() or > GetMetadataItem() is called with "RPC" or "IMD" metadata domain, or when > GetFileList() is called). > > Could you try it and report if it makes things better for you ? > > Another idea to solve the performance problem would be to use an alternate > GDALOpen() where you could provide the papszSiblingFile list. If you read > several files in the same directory, you could build the list one and > provide it multiple times afterwards. > > Best regards, > > Even > > > Often, we need to open many raster files over a network connection > > with thousands of other files residing in the same directory. > > > > > > > > Previously, we were using version 1.7.0 of GDAL (from FW Tools), and > > we used SetConfigOption("GDAL_DISABLE_READDIR_ON_OPEN", "TRUE") > > > > to suppress the automatic search for sibling files. This approach > > served us well. > > > > > > > > We upgraded to 1.8.0. It was quite a bit slower opening the raster > > files. I was able to get GDAL built in debug and stepped through the > > code and discovered the following: > > > > > > > > 1. It searches for several files containing RPC metadata. > > > > 2. It searches for files for PAM as well. > > > > > > > > I was able to use SetConfigOption("GDAL_PAM_ENABLED", "NO") to > > suppress searching for PAM files. > > > > > > > > However, I do not see a way to suppress searching for RPC metadata. > > Does anyone know of a way to do this or other workarounds? If there is > > no way to currently do this, is the community open to adding this option? > > > > > > > > I apologize if this question has been posted previously, but I haven't > > yet found a convenient way to search the archives. > > > > > > > > Thanks, > > > > Kyle _______________________________________________ gdal-dev mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/gdal-dev
