SMP CPUs scaling factors (was "what is a flop")

Bogdan Costescu bogdan.costescu at
Wed Jun 18 09:38:46 EDT 2003

On Wed, 18 Jun 2003, Franz Marini wrote:

> Does anyone have some real world application figures regarding the 
> performance ratio between single and two-way (and maybe four-way) SMP 
> systems based on the P4 Xeon processor ? I'm particularly interested in 
> molecular dynamics code, like, e.g., Gromacs and CPMD. 

If CHARMM figures are also valid:
- when running 2 single-CPU jobs on a 2-way system, real (wall) time of 
each process is the same as if the process was running alone.
- when running a parallel job with shmem/usysv the speed-up is close to 2 
(1.98 or so).

This is with "normal" MD. Using PME might make things different...

Bogdan Costescu

IWR - Interdisziplinaeres Zentrum fuer Wissenschaftliches Rechnen
Universitaet Heidelberg, INF 368, D-69120 Heidelberg, GERMANY
Telephone: +49 6221 54 8869, Telefax: +49 6221 54 8868
E-mail: Bogdan.Costescu at IWR.Uni-Heidelberg.De

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