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Re: AMD vs Intel

From: Leonid Gibiansky <lgibiansky>
Date: Mon, 18 Nov 2019 12:34:18 -0500

Thanks Bob and Peter!

The model is quite stable, but this is LAPLACIAN, so requires second
derivatives. At iteration 0, gradients differ by about 50 to 100%
between Intel and AMD. This leads to differences in minimization path,
and slightly different results. Not that different to change the
recommended dose, but sufficiently different to notice (OF difference of
6 points; 50% more model evaluations to get to convergence).
Thanks
Leonid



On 11/18/2019 12:15 PM, Bonate, Peter wrote:
> Leonid - when you say different. What do you mean? Fixed effect and random effects? Different OFV?
>
> We did a poster at AAPS a decade or so ago comparing results across different platforms using the same data and model. We got different results on the standard errors (which related to matrix inversion and how those are done using software-hardware configurations). And with overparameterized models we got different error messages - some platforms converged with no problem while some did not converge and gave R matrix singularity.
>
> Did your problems go beyond this?
>
> pete
>
>
>
> Peter Bonate, PhD
> Executive Director
> Pharmacokinetics, Modeling, and Simulation
> Astellas
> 1 Astellas Way, N3.158
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> Peter.bonate
> (224) 205-5855
>
>
>
> Details are irrelevant in terms of decision making - Joe Biden.
>
>
>
>
>
>
> -----Original Message-----
> From: owner-nmusers
> Sent: Monday, November 18, 2019 11:05 AM
> To: nmusers <nmusers
> Subject: [NMusers] AMD vs Intel
>
> Dear All,
>
> I am testing the new Epyc processors from AMD (comparing with Intel Xeon), and getting different results. Just wondering whether anybody faced the problem of differences between AMD and Intel processors and knows how to solve it. I am using Intel compiler but ready to switch to gfortran or anything else if this would help to get identical results.
> There were reports of Intel slowing the AMD execution in the past, but in my tests, speed is comparable but the results differ.
>
> Thanks
> Leonid
>
>
>
Received on Mon Nov 18 2019 - 12:34:18 EST

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