[molpro-user] Shared memory question in CCSD(T) calculations

[Jani Salo]

Dear Manhui,

Thank you for your answer.
However my question was a little bit different, briefly:
If 1-core task require e.g. 8Gb of memory and my cores have access to less
than 8Gb, can I reduce memory demand per core by redistribution it over N
cores with lesser memory demand? If I can, what is the recipe?

Thank you very much.
Best,
Jani.

On Fri, Jun 21, 2013 at 2:12 AM, Manhui Wang <wangm9 at cardiff.ac.uk> wrote:

>  Dear Jani,
>
> The setting
> memory, 1000, m
> is for one core. If you use N cores, the total memory will be
> N*1000*1000*1000 Words (ie,  N*1000*1000*1000*8 bytes).
>
> For details, please refer to previous list
>
> http://www.molpro.net/pipermail/molpro-user/2010-April/003723.html
>
> Best wishes,
> Manhui
>
>
>
> On 20/06/13 11:49, Jani Salo wrote:
>
> Dear Molpro Users,
>
> I have specific question about how memory (or shared memory) is used in
> the parallel mode.
> I want to run an CCSD(T)/aug-cc-pVDZ calculation of uracil dimer on my
> small-cluster with 16 cores (with 64 GB of memory)
> It seems that such system needs more than 8GB of memory for 1-core
> calculation, but it very slow, so when I'm trying to do a parallel
> calculation on 2 or 2^N cores
> the memory demand is not reduced by that factor. I've changed "memory,
> 1000, m" option back and forth, but it was not helpful either.
> (I've used compiled mpp-binary Molpro 2012.1 from the website)
> *So Is Molpro distribute used memory over processes or copied the same
> information? *
> How I can control this behavior?
> I've tried to use -G option (even that in manual written that "is no
> longer activated") but it was not helpful. I have not found the answer on
> this question in manual and other sources.
> Can one explain this issue?
>
> Thank you!
>
> Best,
> Jani.
>
>
>
>
> _______________________________________________
> Molpro-user mailing listMolpro-user at molpro.nethttp://www.molpro.net/mailman/listinfo/molpro-user
>
>
> --
> -----------
> Manhui  Wang
> School of Chemistry, Cardiff University,
> Main Building, Park Place,
> Cardiff CF10 3AT, UK
>
>
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