[Pw_forum] Computer cluster Parallel run:-Reg

[Axel Kohlmeyer]

On Tue, Aug 11, 2015 at 7:01 AM, Suresh A <suresh2007pgp19 at gmail.com> wrote:
> Respected Sir/Friends,
>                     I have formed a PC beowulf cluster (X86_64 old PC's made
> on 2007) and installed quantum espresso-5.2.0 in it. Now the cluster is
> running very slowly than the single core i5 processor, DDR3 RAM with 1600MHZ
> speed. The following is my observation in single core i5 processor and in
> beowulf cluster for the titanium dioxide supercell of size 2x2x1. One more
> thing is, in cluster every node has 2GB DDR2 RAM with speed 667 MHZ. for i5
> processor 8GB with 1600 HZ.
>
> total cpu time spent upto now is    408.7 secs   (for  i5 CPU having
> 1600MHZ)
>
> total cpu time spent upto now is    it is keepon running more than 1 hour
> (for one single processor in PC cluster)
>
> total cpu time spent upto now is    1402 secs ( for -ni 10 -nk 10 in PC
> cluster)
>
>
>
> Is this due to RAM speed, size or anything else?

it is due to *everything*: clock rate, memory speed, memory
architecture, processor architecture, processor cache size, disk
caching efficiency, availability of SIMD instructions, compiler,
libraries.
the speed difference you quote seems quite normal for comparing a
single core on current hardware versus 8 year old hardware.

axel.

>
> Looking forward to your valuable suggestions
>
>                   With Regards,
> A.Suresh,
> Research Scholar,
> Madurai Kamaraj University,
> Madurai.
>
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-- 
Dr. Axel Kohlmeyer  akohlmey at gmail.com  http://goo.gl/1wk0
College of Science & Technology, Temple University, Philadelphia PA, USA
International Centre for Theoretical Physics, Trieste. Italy.