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Re: IDL Matrix Multiply and Dual-Core CPUs [message #60328 is a reply to message #60249]

Tue, 20 May 2008 00:21

s.haenger
Messages: 4
Registered: May 2008

Junior Member

On 9 Mai, 20:34, Pierre <pierre.villene...@gmail.com> wrote:
> Hi Samuel,
>
> I saw a very similar problem with my quad-core PC running XP (32 bit)
> with 4gigs of ram. I re-ran my test script on our two-core, 4-gig
> linux box and got similar results with just slightly different array
> sizes. Here is the script I ran:
>
> cpu, /reset
>
> help, !cpu, /str
>
> Nk = 258
> K = fltarr(Nk, Nk)
>
> ;
> ; Case 1.
> ;
> Npix = 129047
> d = fltarr(Npix, Nk)
> t0 = systime(1)
>
> d #= K
>
> t1 = systime(1) - t0
>
> print, 'Case #1: ', Npix, t1
>
> ;
> ; Case 2.
> ;
> Npix = Npix + 1
> d = fltarr(Npix, Nk)
> t0 = systime(1)
>
> d #= K
>
> t2 = systime(1) - t0
>
> print, 'Case #2: ', Npix, t2
>
> On each of our computers case #2 used all available cores while case
> #1 only used one core. The only difference between them is the
> dimension of one of the arrays (Npix) is simply incremented by one.
> The total memory used by the IDL process during this test is never
> more and two-hundred megs or so. There is no way this problem is due
> to a lack of physical memory. The sizes of these arrays are also
> significantly larger then the default minimum number of elements
> (default = 10000) required to enable multi-threading.
>
> Any ideas?
> Pierre

It's not a Windows Problem. We have the same Problem also with
Ubuntu...

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[Message index]

		Re: IDL Matrix Multiply and Dual-Core CPUs By: Pierre V. on Fri, 09 May 2008 11:34
		Re: IDL Matrix Multiply and Dual-Core CPUs By: s.haenger on Fri, 09 May 2008 11:28
		Re: IDL Matrix Multiply and Dual-Core CPUs By: Foldy Lajos on Fri, 09 May 2008 11:20
		Re: IDL Matrix Multiply and Dual-Core CPUs By: Foldy Lajos on Fri, 09 May 2008 11:16
		Re: IDL Matrix Multiply and Dual-Core CPUs By: Bringfried Stecklum on Fri, 09 May 2008 09:09
		Re: IDL Matrix Multiply and Dual-Core CPUs By: s.haenger on Tue, 20 May 2008 00:21
		Re: IDL Matrix Multiply and Dual-Core CPUs By: Karl[1] on Tue, 20 May 2008 11:19
		Re: IDL Matrix Multiply and Dual-Core CPUs By: s.haenger on Thu, 17 July 2008 01:42

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