[gmx-users] Multi-GPU calculation

[Mark Abraham]

On Mar 21, 2014 6:46 AM, "arrow50311" <linxingcheng50311 at gmail.com> wrote:
>
> Hi,
>
> If I put in -gpu_id 0011, will it be the case that the gpu #0 from node 1
be
> assigned to both rank 0  and rank 2?

-gpu_id applies *per-node*, so 0011 is useful only with four ranks *per
node*. Your original question wanted four ranks for the whole calculation
over two nodes, so two ranks per node.

> What I want is the gpu #0 from node 1
> be assigned to rank 0 while gpu #0 from node 2 be assigned to rank 2, is
it
> possible in that way?

Like Szilárd said.

Mark

>
> Thank you,
>
>
> Szilárd Páll-2 wrote
> > Hi,
> >
> > You need to pass mdrun a *per-node* PP-rank-to-GPU mapping, not a
> > global one. Hence, in your case, you should pass -gpu_id 01 (which btw
> > is the default). Similarly, if you want four PP ranks per node with
> > two GPUs, you pass -gpu_id 0011.
> >
> > Cheers,
> > --
> > Szilárd
> >
> >
> > On Thu, Mar 20, 2014 at 12:49 AM, arrow50311
> > &lt;
>
> > linxingcheng50311@
>
> > &gt; wrote:
> >> Hi,
> >>
> >> Imagine I have two nodes, each mounted with 2 GPGPUs. If I want to
> >> require
> >> two nodes and suppose there are 4 PP ranks, is there a way to use 4
> >> GPGPUs
> >> simultaneously in Gromacs 4.6? It seems -gpu_id is not 0123 or 0101,
but
> >> something else.
> >>
> >> Thank you,
> >>
> >>
> >> --
> >> View this message in context:
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