Charm++ parallel programming system

["Kale, Laxmikant V" <kale AT illinois.edu>]

While the answers provided are technically right (you *can* run with +p12 on a one processor system), what I think you *should* do is ti use it with +p1 (or whatever number of physical cores are available to you). Then  you can specifythe number of processors on the target (future) machine as +vp

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From: ppl-bounces AT cs.uiuc.edu [ppl-bounces AT cs.uiuc.edu] on behalf of Pritish Jetley [pjetley2 AT illinois.edu]
Sent: Tuesday, January 10, 2012 12:54 PM
To: Balaji S
Cc: charm AT cs.uiuc.edu
Subject: Re: [ppl] [charm] Charm++ and Bigsim

+p gives the number of processes launched. It is up to the OS to map these processes onto cores. If you launch more processes than there are cores, some cores will host more than one process.

Pritish

On Tue, Jan 10, 2012 at 12:40 PM, Balaji S <balaji.ceg.13 AT gmail.com> wrote:

Hi sir,
        Thanks for the prompt reply. But my doubt is, when i run the example program "nqueens" with "./pgm 12 6 +p4"
and "./pgm 12 6 +p8" I get different runtime , but i have "intel i3 processor running on 64 bit ubuntu 10.04", if +p is real
processors, how i ll get different answers for +p4 and +p8 ( since i don hav even 4 cores/processors) ?

Regards,
Balaji Sekar

On Tue, Jan 10, 2012 at 12:45 PM, Celso L. Mendes <cmendes AT illinois.edu> wrote:

The "+p" parameter indicates the number of physical (i.e. real)
processors where the program will be running.

There is another parameter, "+vp", which indicates the number
of virtual processors. Thus, you can run, say, with "+p 8 +vp 128"
where each physical processor will be in charge of 16 virtual
processors.

BigSim explores this capability to simulate future machines.
Each virtual processor assumes the role of a target processor
of the future machine. In the example above, you would be using
a current machine with 8 existing processors to simulate a future
machine with 128 processors.

-Celso

On 1/10/2012 11:30 AM, Balaji S wrote:

Hi ,

I am new to charm++. I have read that bigsim is used to simulate more number of processors,
When in charm++, u can specify the option (as a commandline argument ) +p8 or +p32 to indicate
number of processors, what is need for a separate simulator like bigsim?

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With Regards,
Balaji.S

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With Regards,
    Balaji.S

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Pritish Jetley
Doctoral Candidate, Computer Science
University of Illinois at Urbana-Champaign