[Pw_forum] speedup of md simulation

[Paolo Giannozzi]

HI

> [...] I installed pwscf on my Linux/alpha cluster (10 dual processors),which
> employs LAM/MPI [...] I found that the speedup is only a factor of 2
> [...]
> (2) is this due to the fact that the code is not optimally parallelized
>     or that the LAM/MPI is not well configured?

...or none of the above? unless your cluster has high-speed communication
hardware (i.e. Myrinet, not Ethernet), you will not get a good speedup.
You may even get "speedown" instead.

>  [...] PS: When I do k-point scf calculation, the speedup is acceptable,
> around a factor of 5 or so.

you mean parallelization on k points ? it requires much less communication
than parallelization on plane waves. See also
http://www.pwscf.org/performance.htm#parallelization

Paolo

-- 
Paolo Giannozzi             e-mail:  giannozz at nest.sns.it
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