[AMBER] GPU vs CPU test

From: Massimiliano Porrini <M.Porrini.ed.ac.uk>
Date: Thu, 27 Jan 2011 15:06:29 +0000

Dear all,

I had the possibility to run Amber11 across 2 Tesla C2050 GPUs and,
in order to check the accuracy of the simulation, I ran exactly the
same simulation on 4 CPUs, using the same Langevin random number
ig generated from the GPU run.

Below there is the input file I used for my system (1561 atoms):

 imin = 0, irest = 1, ntx = 5,
 ntb = 0,
 igb = 5,
 cut = 999.0,
 temp0 = 343.0,
 ntt = 3, gamma_ln = 1.0, ig = -1,
 ntc = 2, ntf = 2,
 nstlim = 500000000, dt = 0.002,
 ntpr = 5000, ntwx = 1000, ntwr = 5000,

For the CPU run I used ig = 857210 .

I attached also a graph with RMSD values and a breakdown of energies
calculated for both GPU and CPU runs.

Since I used the same random number for Langevin dynamics,
should I expect exactly the same behavior of RMSD and energies?

Or the values in the graph compare anyway well and I am on the safe
side with regard to the accuracy of my GPU simulation?
If so, I would guess Amber has another source to make the values unreproducible.

Thanks in advance.

All the best,

PS: I hope the graph is understandable.

Dr. Massimiliano Porrini
Institute for Condensed Matter and Complex Systems
School of Physics & Astronomy
The University of Edinburgh
James Clerk Maxwell Building
The King's Buildings
Mayfield Road
Edinburgh EH9 3JZ
Tel +44-(0)131-650-5229
E-mails : M.Porrini.ed.ac.uk

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Received on Thu Jan 27 2011 - 07:30:02 PST
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