[Users] Simfactory: Machine definition variables

[Dumsani Ndzinisa]

Hi Erik, everyone,

Thanks for the explanation. It really helps.

Kind regards,
Dumsani

On 09/08/2014 16:11, Erik Schnetter wrote:
> On Aug 9, 2014, at 8:45 , Dumsani Ndzinisa <g14n8326 at campus.ru.ac.za> wrote:
>
>> Hi everyone,
>>
>> I am trying to configure and  add a new machine (cluster) into my
>> Simfactory machine database. (.../simfactory/mdb/machinses/).
>>
>> However, I do not know what exactly what the following variables or
>> abbreviations are in the .ini file: spn, mpn. I have looked up values
>> given to these in different machine files and found that they are not
>> the same for all machines. Which brings me to the question of what
>> they are so I can give to them the correct values relevant to/for the
>> new machine that I want to add.
>>
>> I understand ppn represents the number processors per node or
>> number of cores per node (SimfactoryAdvancedTutorial) . On this
>> one, what exactly should determine the value for min-ppn as far
>> as the machine being defined is concerned? Or the min-ppn's
>> value doesn't depend on the machine?
>>
>> Thank you in advance fr your help.
> The MDB entries are defined in simfactory/etc/syntax/mdb-syntax.ini.
>
> spn is "sockets per node"; this value was introduced, but is currently unused. Manufacturer abused the term "socket", so that this number is useless in practice.
>
> mpn is "memory systems per node"; this should probably be called "NUMA nodes per node". If you are using OpenMP, the you likely either want 1 MPI process per node, or 1 MPI process per NUMA node. If you do not know this number, it is pretty safe to set it to 1. Tools such as hwloc can determine this number.
>
> ppn is the number of cores per node, a hardware property. min-ppn is the minimum ppn you can request for a job; this is a software property enforced by the queuing system. Simfactory will automatically (excluding bugs) round up your request to the next multiple of min-ppn. In practice, most HPC systems either have min-ppn=1 or min-ppn=ppn.
>
> -erik
>