[SimGrid-user] Using the Cluster tag in the platform file

degomme augustin.degomme at unibas.ch
Tue Jun 13 19:35:39 CEST 2017


Hello,

1/Indeed this can be simulated, with the loopback tags. You should check 
loopback_lat and loopback_bw attributes on 
http://simgrid.gforge.inria.fr/simgrid/3.16/doc/platform.html#pf_tag_cluster. 
This just creates a (fatpipe) link with a different bw/latency.
2/ For a fatpipe, if there is no loopback, it will go through the 
network, and probably up then down a level to find itself (have to be 
confirmed). So it woul be roughly equivalent to reaching a close 
neighbour node.

Best regards,

Augustin

On 13/06/2017 19:25, Ahmed Hamdy Mohamed Eleliemy wrote:
> Hi everyone,
>
> I am trying to represent a small cluster in a platform file to use it 
> with SMPI. I am using the cluster tag in my platform representation. 
> However, I am facing a problem with respect to the representation 
> multi-core host in the cluster tag.
> I do the following
>  <cluster id="miniHPC" prefix="cl-node" suffix="" radical="0-23" 
> core="20" speed="38.3Gf"  bw="100Gbps" lat="100ns"   
> topology="FAT_TREE" topo_parameters="2;12,2;1,2;2,12"/>
> my question:
> 1. Does SimGrid realise the messages between cores? i.e, I mean mpi 
> ranks on cores belong to the same host should encounter different 
> bandwidth and latency comparing to mpi ranks running on cores of 
> different hosts.
> 2. If yes, what is default bandwidth and the latency? how to change it 
> especially when using the cluster tag.
>
> Best regards
> Ahmed
>
>
>
> Ahmed Eleliemy
> High Performance Computing Group
> Mathematics and Computer Science Department
> University of Basel
> Spiegelgasse 1
> CH-4051 Basel Switzerland
> Phone: +41 (0)768232581
>
>
>
>
>
>
>
>
>
> _______________________________________________
> Simgrid-user mailing list
> Simgrid-user at lists.gforge.inria.fr
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