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Re: Writing a very large file [message #57419 is a reply to message #57418]

Fri, 07 December 2007 12:23

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

wlandsman writes:

> So the first four images take ~0.3s each to write, while subsequent
> images require more than 6 seconds each. I suspect that the slowing
> down is due to IDL (or the OS) needing to extend the file size. (I
> checked that it is not a memory usage problem.) So I think
> things would speed up if I could specify the final file size at the
> beginning -- perhaps there is a way to do this in Unix? I have
> experimented with the BUFSIZE and RAWIO keywords to OPENW but so far
> without any improvement.

I don't have any suggestions, but I wonder if disk fragmentation
might have something to do with it? Perhaps it is faster if
it can grab contiguous memory space.

Cheers,

David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")

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[Message index]

		Re: Writing a very large file By: Bringfried Stecklum on Sat, 08 December 2007 08:19
		Re: Writing a very large file By: Kenneth Bowman on Fri, 07 December 2007 20:50
		Re: Writing a very large file By: Jim Pendleton, ITT Vi on Fri, 07 December 2007 13:47
		Re: Writing a very large file By: Jean H. on Fri, 07 December 2007 13:23
		Re: Writing a very large file By: pgrigis on Fri, 07 December 2007 12:39
		Re: Writing a very large file By: David Fanning on Fri, 07 December 2007 12:23
		Re: Writing a very large file By: wlandsman on Mon, 10 December 2007 07:24
		Re: Writing a very large file By: Kenneth Bowman on Mon, 10 December 2007 07:43

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