[CP2K-user] [CP2K:17016] Re: CP2K Hardware Requirements

[Sam Broderick]

Hi NÍcolas


It depends heavily on the problem (what you ask cp2k to calculate) and how 
you run cp2k. Take a look at the output file to understand the memory - 
unfortunately, cp2k doesn't tell you memory used directly, but rather total 
and available, so you have to subtract.


The hyper-threading might be doing something, but it can also slow down 
your calculation. I use:


mpirun -n 2 --bind-to numa --map-by numa -display-map cp2k.psmp -i 
my-cp2k-run.inp > my-cp2k-run.out



   1. The 'bind-to numa' and 'map-by numa' make use of the os's 
   understanding of the processor. 
   2. These two together neatly puts the mpi ranks per cpu socket. 
   3. The '-display-map' writes the mpi assignments at the beginning of the 
   output. 


Kind Regards


Sam

On Friday, May 20, 2022 at 4:17:27 PM UTC+2 Nícolas wrote:

> Hi everyone!
>
> According to this documentation: 
> https://brehm-research.de/files/spec_tutorial_2018.pdf I need to have 4 
> GiB of RAM per CPU core, but I can run CP2K with 128 process on a machine 
> with 2 sockets of 32 cores per socket and 2 thread per core, totalizing 128 
> threads and 64 cores, although that machine has only 128GB of RAM.
>
> Does anyone knows why can I do this?
>
> P.S.: In another machine with 2 sockets of 64 cores per socket, 2 thread 
> per core and 512GB of RAM, when I run CP2K with 128 proccess I got Out Of 
> Memory(OOM).
>
> Thank you.
> Nícolas
>

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