[FLASH-USERS] Flash memory usage.

[Anshu Dubey]

The amount of static memory allocated is directly related to the number of
maxblocks you specify at compile time. Then there is local storage in
modules that goes on the stack and is usually dependent on the size
of the individual block. Hdf5_serial IO has relatively large dynamic
allocation, roughly the size of the local mesh on the processor, and
paramesh does its own dynamic allocation during communication. This
allocation depends upon the amount of data that needs to move between
processors. So the only way allocation is really influenced by spreading
work out on more nodes is by cutting down the maxblocks proportionately.
Maxblocks itself is a local quantity, it is the maximum number
of blocks you anticipate having on any one processor at any time during
your simulation.

I hope that answers your question, if you need further clarification please
let me know.

Anshu


> How does flash do memory allocation?  If I am running into memory
> problems but my only option for more memory is to run on more nodes
> does flash subdivide the amount of memory in use evenly?
> For example:
>
> a model when running on 4 cpus, each process takes 10GB of real memory.
>
> If I run that same model on 8 how close will each process get to 5 gb
> of use?
>
> Brock Palen
> Center for Advanced Computing
> brockp at umich.edu
> (734)936-1985
>
>