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Re: load sharing on multiple machines? [message #28872]

Fri, 18 January 2002 07:33

Craig Markwardt
Messages: 1869
Registered: November 1996

Senior Member

"Mark Rivers" <rivers@cars.uchicago.edu> writes:

> Michael A. Miller <mmiller3@iupui.edu> wrote in message
> news:87sn9469qq.fsf@lumen.med.iupui.edu...
>> Thanks for the feedback, Mark. Our main systems also have
>> dual-CPU slots, although we haven't yet filled the second one.
>> Do you have any ball-park numbers for how much IDL performance
>> improvement you see when you use two instead of one processors?
>
> I just ran a test on Linux
> IDL> a = findgen(1000,1000)
> IDL> b = findgen(1000,1000)+1.
> IDL> for i=0,1000 do c=a/b
>
> I monitored the system performance with "top". Both CPUs went from 1% busy
> to 100% busy, indicating that IDL is using both CPUs effectively.
>
> On the other hand:
> IDL> for i=0,100 do c=fft(a,1)
> the sum of the 2 CPUs busy was about 120%, indicating that it's not using
> both CPUs very well.

I recall reading the What's New document for IDL 5.5, which says that
some mathematical operations can become multi-threaded, and hence use
multiple CPUs. I suspect that this is much more difficult to
implement for the FFT, so it isn't. Of course, this only applies to
IDL 5.5.

Craig

--
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Craig B. Markwardt, Ph.D. EMAIL: craigmnet@cow.physics.wisc.edu
Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
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[Message index]

		Re: load sharing on multiple machines? By: Craig Markwardt on Fri, 18 January 2002 07:33
		Re: load sharing on multiple machines? By: Mark Rivers on Thu, 17 January 2002 20:34
		Re: load sharing on multiple machines? By: Pavel A. Romashkin on Thu, 17 January 2002 09:36
		Re: load sharing on multiple machines? By: mmiller3 on Thu, 17 January 2002 11:46
		Re: load sharing on multiple machines? By: Mark Rivers on Wed, 16 January 2002 20:07

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