Charm++ parallel programming system

[Eric Bohm <ebohm AT illinois.edu>]

Hello Jozsef,

Procnum will be called to construct your chare, the first time a message is sent to it from a node, and each time subsequent sends do not find a precached location record for it.  The latter event can occur when many sends have pushed it out of cache, or after migration.  

The potential global memory footprint of location management caching is proportional to the total number of objects multiplied by the number of nodes.  Therefore, the runtime system keeps a finite number on each node.  At the limit, procnum could be called for nearly every message send, therefore procnum should be designed to be inexpensive. 

On 05/19/2015 09:23 AM, Jozsef Bakosi wrote:

Hi folks,

I'm trying to create an array map for custom initial placement of chare array elements.

If I create my array with 1 element on a single PE, procNum() is called twice. If I create my array with 2 elements on 2 PEs, procNum() is called 3 times for array index 0 and 4 times for array index 1. Can someone explain the mchanism behind this?

Also, is this the procNum() function called many times or just at array creation, element migration? Is it okay to put some potentially expensive calculation in there?

Thanks,

Jozsef

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