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Subject: Re: [OMPI devel] confusion between slot and procs on mca/rmaps
From: Ralph Castain (rhc_at_[hidden])
Date: 2010-12-01 00:33:01


Afraid I don't speak much slurm any more (thank goodness!).

>From your output, It looks like the system is mapping bynode instead of byslot. IIRC, isn't bycore just supposed to be a pseudonym for byslot? So perhaps the problem is that "bycore" causes us to set the "bynode" flag by mistake. Did you check that?

BTW: when running cpus-per-proc, a slot doesn't have X processes. I suspect this is just a language thing, but it will create confusion. A slot consists of X cpus - we still assign only one process to each slot.

On Nov 30, 2010, at 10:47 AM, Damien Guinier wrote:

> hi all,
>
> Many time, there are no difference between "proc" and "slot". But when you use "mpirun -cpus-per-proc X", slot have X procs.
> On orte/mca/rmaps/base/rmaps_base_common_mappers.c, there are a confusion between proc and slot. this little error impact mapping action:
>
> On OMPI last version with 32 cores compute node:
> salloc -n 8 -c 8 mpirun -bind-to-core -bycore ./a.out
> [rank:0]<stdout>: host:compute18
> [rank:1]<stdout>: host:compute19
> [rank:2]<stdout>: host:compute18
> [rank:3]<stdout>: host:compute19
> [rank:4]<stdout>: host:compute18
> [rank:5]<stdout>: host:compute19
> [rank:6]<stdout>: host:compute18
> [rank:7]<stdout>: host:compute19
>
> with patch:
> [rank:0]<stdout>: host:compute18
> [rank:1]<stdout>: host:compute18
> [rank:2]<stdout>: host:compute18
> [rank:3]<stdout>: host:compute18
> [rank:4]<stdout>: host:compute19
> [rank:5]<stdout>: host:compute19
> [rank:6]<stdout>: host:compute19
> [rank:7]<stdout>: host:compute19
>
> Can you say, if my patch is correct ?
>
> Thanks you
>
> Damien
>
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