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Re: AMD vs Intel

From: Ruben Faelens <ruben.faelens>
Date: Mon, 18 Nov 2019 20:20:53 +0100

Hi all,

The Intel fortran compiler has a switch - fp-strict that switches off
numerical optimization.
See also
https://software.intel.com/sites/default/files/comment/1721462/03-fp-consistency-2012.pdf

Op ma 18 nov. 2019 18:42 schreef Leonid Gibiansky <lgibiansky
>:

> 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
> > Northbrook, IL 60062
> > Peter.bonate
> > (224) 205-5855
> >
> >
> >
> > Details are irrelevant in terms of decision making - Joe Biden.
> >
> >
> >
> >
> >
> >
> > -----Original Message-----
> > From: owner-nmusers
> Behalf Of Leonid Gibiansky
> > 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 - 14:20:53 EST

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