| IDL and Macs. Speed is not only about squared roots [message #49306] |
Fri, 14 July 2006 00:17  |
jgc
Messages: 10
Registered: July 2006
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Junior Member |
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Dear all,
I tried the tests decribed in topic
http://groups.google.com/group/comp.lang.idl-pvwave/browse_t hread/thread/da3a8dd9a11276d3/87f9e46339684e43#87f9e46339684 e43
in a rather unfair fashion (IDL 6.0 on windows PC 1.4 GHZ against IDL
6.3 Mac OS X 2.16 GHz Intel duo) and results were, as expected:
0.02 against 0.88 to the advantage of the Mac (for
a=randomu(sd,100L*10000l) as the pc didn't have enough memory.
However there is more in life than squared roots, so I was dissapointed
to see that a complex program, involving large array manipulation,
input and output, and loops reduced to a minimum, took almost double
the time in the Mac than in the windows PC. This is a energy balance
model for snow ablation over a glacier in the Alps
(http://www.arolla.ethz.ch/snowdem.html).
One summer simulation took 22 minutes on IDL 6.0 in the windows PC 1.4
GHz and 42 minutes on the Mac Intel 2.16 GHz with IDL 6.2. Almost
double in a much more powerful computer! IDL 6.3 seems slightly
better but still slower (I'm waiting for the full license to test it).
I did additional texts such as repeatig more complex processes (my
shading algorithm, http://www.ittvis.com/codebank/search.asp?FID=141).
Here the mac outperforms the pc. Thus, obviously there must be just a
few inefficient processess for the Mac, which slow down the wole thing.
I wonder if anybody has identified which are these processes, so that
we can optimize the code by avoiding them as much as possible.
Thanks,
Javier
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| Re: IDL and Macs. Speed is not only about squared roots [message #49390 is a reply to message #49306] |
Fri, 14 July 2006 10:51  |
JD Smith
Messages: 850
Registered: December 1999
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Senior Member |
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On Fri, 14 Jul 2006 00:17:13 -0700, jgc wrote:
> Dear all,
>
> I tried the tests decribed in topic
> http://groups.google.com/group/comp.lang.idl-pvwave/browse_t hread/thread/da3a8dd9a11276d3/87f9e46339684e43#87f9e46339684 e43
> in a rather unfair fashion (IDL 6.0 on windows PC 1.4 GHZ against IDL
> 6.3 Mac OS X 2.16 GHz Intel duo) and results were, as expected:
> 0.02 against 0.88 to the advantage of the Mac (for
> a=randomu(sd,100L*10000l) as the pc didn't have enough memory.
You need to try the (very recently released) version of IDL 6.3
re-compiled for Intel. It should mention darwin x86 at the top when
you start up. BTW, there are *two* version of IDL 6.3 for Macs: the
one available before yesterday, and the one available after yesterday.
You need the latter. You can also:
IDL> print,!VERSION.OS,',',!VERSION.ARCH
to see which you've got.
JD
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