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Subject: Re: [OMPI users] Best way to reduce 3D array
From: Ricardo Reis (rreis_at_[hidden])
Date: 2010-03-31 03:27:13

On Tue, 30 Mar 2010, Gus Correa wrote:

> Salve Ricardo Reis!
> Como vai a Radio Zero?

:) busy, busy, busy. we are preparing to celebrate Yuri's Night, April the

> Doesn't this serialize the I/O operation across the processors,
> whereas MPI_Gather followed by rank_0 I/O may perhaps move
> the data faster to rank_0, and eventually to disk
> (particularly when the number of processes is large)?

oh, yes. I remember now why I thought of this. If the problem is large
enough you will run out of memory in the master machine (for me MPI-IO is
the way to go unless you're tied up with NFS). Off course one could always
send it by chunks, let the master write, then send other chunk...


  Ricardo Reis

  'Non Serviam'

  PhD candidate @ Lasef
  Computational Fluid Dynamics, High Performance Computing, Turbulence

  Cultural Instigator @ Rádio Zero

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