>Because communicating through shared memory when sending messages 
between processes on the same server is far faster than going through a 
network stack.
 
I see... But that is not good for diskless clusters. Am I right? assume 
processes are on a node (which has no disk). In this case, their communication 
go though network (from computing node to server) then IO and then network 
again (from server to computing node).


Regards,
Mahmood



________________________________
 From: Jeff Squyres <jsquy...@cisco.com>
To: Mahmood Naderan <nt_mahm...@yahoo.com>; Open MPI Users <us...@open-mpi.org> 
Sent: Saturday, October 27, 2012 6:19 PM
Subject: Re: [OMPI users] openmpi shared memory feature
 
On Oct 27, 2012, at 10:49 AM, Mahmood Naderan wrote:

> Why openmpi uses shared memory model?

Because communicating through shared memory when sending messages between 
processes on the same server is far faster than going through a network stack.

> this can be disabled though by setting "--mca ^sm". 
> It seems that by default openmpi uses such feature (shared memory backing 
> files) which is strange.
>  
> Regards,
> Mahmood
> _______________________________________________
> users mailing list
> us...@open-mpi.org
> http://www.open-mpi.org/mailman/listinfo.cgi/users


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Jeff Squyres
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