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Re: IDL program runs faster on slower CPU [message #88081 is a reply to message #88074]

Wed, 19 March 2014 01:45

Deckard++;
Messages: 11
Registered: March 2010

Junior Member

Le mercredi 19 mars 2014 02:47:56 UTC+1, Craig Markwardt a écrit :
> On Tuesday, March 18, 2014 8:22:44 AM UTC-4, Arthur Vigan wrote:
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>> Le lundi 17 mars 2014 18:33:27 UTC+1, Craig Markwardt a écrit :
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>>> On Sunday, March 16, 2014 6:15:04 PM UTC-4, Arthur Vigan wrote:
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>>>> Strangely, the code runs about 4 to 5 times faster on the MacBook Pro. The code is strictly identical, with the same starting point, and it finds exactly the same result in the same number of iterations. I also mention that the program does not rely on disk access that could slow things down: all the data is in memory.
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>>> I would suggest using PROFILER to find out where the bottleneck is. My first guess is you have some numerical faults like NaNs which are being handled by the two platforms differently. Sometimes numerical exceptions are handled very slowly because they take a round trip to the kernel.
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>> It could be a possibility, but after running the profiler I am not so sure. The profiler output seems to show very mixed results, with some things running faster on the Mac, and some things running faster on the server. But more generally, any complex program seems to run faster on the Mac
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>> I just ran a simple test on the two machines:
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> ...
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> It's still worth it to check your actual problem, not a simple test.
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> CM

Yes, true. I have investigated a bit more by placing systime(/sec) commands around different portions of my code, and the result is what I was saying above: every chunk of code seems to run slower on the linux workstation.

Concerning the numerical faults that you were mentioning, do you know if there is any way to check if there are any? Are they reported somewhere by the system, triggering some kind of message?

-- Arthur;

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[Message index]

		IDL program runs faster on slower CPU By: Deckard++; on Sun, 16 March 2014 15:15
		Re: IDL program runs faster on slower CPU By: Craig Markwardt on Mon, 17 March 2014 10:33
		Re: IDL program runs faster on slower CPU By: Deckard++; on Tue, 18 March 2014 05:22
		Re: IDL program runs faster on slower CPU By: Jim Pendleton on Tue, 18 March 2014 14:40
		Re: IDL program runs faster on slower CPU By: Craig Markwardt on Tue, 18 March 2014 18:47
		Re: IDL program runs faster on slower CPU By: Deckard++; on Wed, 19 March 2014 01:45
		Re: IDL program runs faster on slower CPU By: Craig Markwardt on Wed, 19 March 2014 10:45
		Re: IDL program runs faster on slower CPU By: Deckard++; on Wed, 19 March 2014 12:47
		Re: IDL program runs faster on slower CPU By: Craig Markwardt on Wed, 19 March 2014 16:06

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