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Re: Speeding up I/O [message #38534 is a reply to message #38533]

Tue, 16 March 2004 19:09

marc schellens[1]
Messages: 183
Registered: January 2000

Senior Member

Ken Knapp wrote:
> Are there any tricks to speed up I/O?
> Situation: I have 1.2 TB of data to process. The following is a typical
> read statement:
> in = {header:bytarr(128),scan:intarr(1250)}
> image = replicate(in,1250)
> openr,1,file
> readu,1,image
> close,1
> Then I process the image and output something. The slow part is in the
> readu [I used profiler to find that readu IS slowing me down, the
> computations are only a fraction of the read time].
> Any suggestions on how to speed it up?
> Tricks to make the computer find files faster?
> Would Fortran/C be faster?
>
> Any help is greatly appreciated.
> -Ken

The fastest you can get would be to read in one array instead of
an array of structures:

image = intarr( 128/2 + 1250, 1250)
openr,1,file
readu,1,image
close,1

Then you have to separate the header yourself and convert it
back to byte.

Anyway, this method is almost as fast as it gets (almost like C).
About 80% faster than the one using structures on my machine.

HDH,
marc

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[Message index]

		Re: Speeding up I/O By: Rick Towler on Wed, 17 March 2004 08:49
		Re: Speeding up I/O By: Ken Knapp on Wed, 17 March 2004 05:19
		Re: Speeding up I/O By: schaa on Wed, 17 March 2004 00:41
		Re: Speeding up I/O By: marc schellens[1] on Tue, 16 March 2004 19:09
		Re: Speeding up I/O By: R.G. Stockwell on Tue, 16 March 2004 15:53

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