Charm++ parallel programming system

[Evghenii Gaburov <e-gaburov AT northwestern.edu>]

Thanks for quick reply!

> If the array is large, you should consider a nodeGroup (on a multicore SMP
> implementation)
I tried nodeGroup and it works great, memory consumption drops dramatically!

One question though, I access a CkVec<boundary> array via

myChare::do_work()
{
  domains = (globalDomains*)CkLocalNodeBranch(globalDomainsNodeGroup);
  const CkVec<boundary> &proc = domains->domainsBoundary;
  do_stuff(procs[thisIndex]);
}

is there some potential (performance) penalty involved in such access? Is it 
as simple as 
the globalDomains::domainsBoundary address space is visible by all processes 
on a node, 
or there is some (hidden) machinery involved in moving data around?

Thanks!

Cheers,
 Evghenii



> -- 
> Laxmikant (Sanjay) Kale         http://charm.cs.uiuc.edu
> <http://charm.cs.uiuc.edu/>
> Professor, Computer Science     
> kale AT illinois.edu
> 201 N. Goodwin Avenue           Ph:  (217) 244-0094
> Urbana, IL  61801-2302          FAX: (217) 265-6582
> 
> 
> 
> 
> 
> 
> On 10/1/11 11:22 PM, "Evghenii Gaburov" 
> <e-gaburov AT northwestern.edu>
>  wrote:
> 
>> Hi All,
>> 
>> In my Charm program I have an array declared as readonly:
>> 
>> *.ci:    readonly CkVec<boundary> domains_boundary;
>> Main.h:  extern   CkVec<boundary> domains_boundary;
>> Main.cpp:         CkVec<boundary> domains_boundary;
>> 
>> which holds boundaries of each of the chare domain (this is a part of the
>> domain decomposition code).
>> 
>> These arrays are initially set in the Mainchare constructor, however,
>> they change dynamically during runtime as well (by a method in Mainchare,
>> which is called outside the constructor from a threaded method). As I
>> understand, the changes done outside the Mainchare constructor won't be
>> communicated to other processors automatically.
>> 
>> I was wondering how can I manually communicate the updated array to the
>> rest of the processors?
>> 
>> I cannot communicate these to each of the chare (which currently do),
>> since once the number of chares becomes large (>1024), too much memory is
>> consumed unnecessary (quadratic scaling with #chares)); so I want to keep
>> these arrays as global arrays.
>> 
>> Any suggestions/advice?
>> 
>> Thanks!
>> 
>> Cheers,
>> Evghenii
>> 
>> 
>> --
>> Evghenii Gaburov, 
>> e-gaburov AT northwestern.edu
>> 
>> 
>> 
>> 
>> 
>> 
>> 
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--
Evghenii Gaburov, 
e-gaburov AT northwestern.edu