Open MPI logo

Open MPI User's Mailing List Archives

  |   Home   |   Support   |   FAQ   |   all Open MPI User's mailing list

Subject: Re: [OMPI users] BTL question
From: Pavel Shamis (Pasha) (pashash_at_[hidden])
Date: 2008-12-24 08:59:28


Teige, Scott W wrote:
> Greetings,
>
> I have observed strange behavior with an application running with
> OpenMPI 1.2.8, OFED 1.2. The application runs in two "modes", fast
> and slow. The exectution time is either within one second of 108 sec.
> or within one second of 67 sec. My cluster has 1 Gig ethernet and
> DDR Infiniband so the byte transport layer is a prime suspect.
>
> So, is there a way to determine (from my application code) which
> BTL is really being used?
You may specify:
--mca btl openib,sm,self
And OpenMPI will use IB and shared memory for communication.
--mca btl tcp,sm,self
And OpenMPI will use TCP and shared memory for communication.

Thanks,
Pasha