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Subject: Re: [OMPI users] dual cores
From: Raymond Wan (rwan_at_[hidden])
Date: 2008-11-10 00:20:57


Dear Erin,

I'm nowhere near a guru, so I hope you don't what I have to say (it
might be wrong...).

But what I did was just put a long loop into the program and while it
was running, I opened another window and looked at the output of "top".
Obviously, without the loop, the program would terminate too fast.

If you have two CPUs and the total of the process exceeds 100% (i.e., if
you run with np=2, you might have 98% and 98%), then I would think this
is enough proof that both cores are being used.

I'm saying this on the list hoping that someone can correct my knowledge
of it, too...

Ray

Hodgess, Erin wrote:
> Dear Open MPI gurus:
>
> I have just installed Open MPI this evening.
>
> I have a dual core laptop and I would like to have both cores running.
>
> Here is the following my-hosts file:
> localhost slots=2
>
> and here is the command and output:
> mpirun --hostfile my-hosts -np 4 --byslot hello_c |sort
> Hello, world, I am 0 of 4
> Hello, world, I am 1 of 4
> Hello, world, I am 2 of 4
> Hello, world, I am 3 of 4
> hodgesse_at_erinstoy:~/Desktop/openmpi-1.2.8/examples>
>
>
> How do I know if both cores are running, please?
>