[Pw_forum] Swapping

Carlo Nervi carlo.nervi at unito.it
Tue Oct 25 19:52:18 CEST 2011


> Dear Quantum Espresso Users
>
> I think the jobs run slow when they are swapping memory to
> disk.
> Is there anything I can do to distribute the memory across
> more nodes so
> they don’t have to swap?
> I want to reduce RAM usage in practice. How it is
> possible?

It is generally a very bad idea to swap RAM on the HD.
Try to reduce the amount of RAM decreasing the size of the
problem (i.e. reduce cell dimensions, use lower ecut,
etc...)
There is also another parameter to be considered,
especially in parallel calculations:
in namelist &CONTROL  disk_io='minimal', or even 'none'
see here:
http://www.quantum-espresso.org/user_guide/node18.html

HTH,
 Carlo


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