[gdal-dev] Can GDAL be configured to do direct I/O? (bypass cache, control blocksize, etc)

Ivan Lucena ivan.lucena at princeton-ma.us
Fri Dec 14 06:30:50 PST 2012


Interesting: http://www.centos.org/docs/4/html/rh-gfs-en-6.1/s1-manage-direct-io.html

>  -------Original Message-------
>  From: Ethan Alpert <ealpert at digitalglobe.com>
>  To: gdal-dev at lists.osgeo.org
>  Subject: [gdal-dev] Can GDAL be configured to do direct I/O? (bypass cache, control blocksize, etc)
>  Sent: Dec 14 '12 09:14
>  
>  I’m running in to a situation where I believe the filesystem cache
>  settings are screwing things up. Based on iozone tests I’m not
>  getting near the throughput I should for large 4gb+ files with multiple
>  writing processes. It is a complex interaction of the number of dirty pages
>  in filesystem cache in combination with small blocksize of the filesystem.
>  I’m still trying to figure this out but I can now get these machines
>  to tip over with just iozone.
>  
>  
>  I’m actively working on how to refactor this code base to use GDAL
>  WriteBlock but in absence of a solution there I’m wondering if
>  there’s anyway to get GDAL writing using O_DIRECT?
>  
>  
>  Thanks,
>  
>  
>  -ethan
>  
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