[Wien] lapw2c tries to read an anomalous amount of data

[Laurence Marks]

Aaaah, it sounds like you are swapping, either each core or the different
cores (assuming that you have shared memory). That is, since all four cores
cannot run at the same time due to the memory available, they are being
swapped to and from swap space (which is probably on disc).

Wien2k is not well optimized for this type of issue, and often memory can
be an issue. At one time one of my students was running a large problem on
a supercomputer with 32 cores/node but only 64Gb memory, and ended up only
being able to use 16-20 cores.

The mpi versions may work better for you as they somewhat (not perfectly)
split the code so can use less memory. Whether this is faster will depend
upon your hardware; I have always found mpi to be faster but I know that on
some of Peter's computers this is not true.

Or buy some more RAM!

On Fri, Jul 26, 2019 at 8:58 AM Luc Fruchter <luc.fruchter at u-psud.fr> wrote:

> I think it is unlikely related to a specific machine or OS problem: I
> encountered the same situation with different machines types, different
> OS (Redhat Sci. Linux, Ubuntu), different Intel compilers versions (from
> 2017 to 2019). But it could be some common configuration problem.
>
> I don't use mpi, and yes there four 9.6 Gb .vector files (there is 4
> CPUs used), the total of which exceeds the total memory (24 Gb), while
> the four lapw1 processes only used 20 Gb.
>
> I still have to figure out what is the memory needed for lapw2s, even
> when it is sufficient for lapw1s. I will try to reduce the number of
> CPUs, to see if the total .vector files size is the problem for lapw2s.
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-- 
Professor Laurence Marks
Department of Materials Science and Engineering
Northwestern University
www.numis.northwestern.edu
Corrosion in 4D: www.numis.northwestern.edu/MURI
Co-Editor, Acta Cryst A
"Research is to see what everybody else has seen, and to think what nobody
else has thought"
Albert Szent-Gyorgi
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