Re: [Swarm-Modelling] SWARM on Clusters

[James Marshall]

Hi,
  don't forget the easiest form of parallelism... job farming, is easily
achievable with Swarm. I had this set up on my last project (using Sun
Grid Engine on a cluster) and it's very handy if you have to do lots of
sensitivity or robustness analysis. There used to be something called
Drone to do a similar thing but I'm not sure it's maintained?
  Also I don't think Russel Standish has contributed to the discussion
yet but he has lots of experience in this area... check out the High 
Performance
Computing Support Unit at the University of New South Wales.
  Regards,
    James

> Sunwoo Park wrote:
>
> > Dear Marcus,
> > I really appreciate for your comments.
> >
> > As my understanding, you claimed that message passing is not good for 
> > SWARM
> > mainly because communication overhead between agents might be nontrivial.
> > Right ? But, for example, (1) if models perform considerable amount of 
> > computation in a single
> > simulation phase (or cycle) with minimum communication between agents
> > (2) if the size and/or scalability of simulation models is much important
> > than performance (or execution time)
> > do you still think multi-threading approach is better than message 
> > passing
> > because of the nature of SWARM even in above cases ?
> >
> > Also, could you give me some information (or link) on SWARM 
> > models/projects
> > that are already done or planned for 'large-scale' simulation  ?
> > For example, is there any SWARM project that uses more than 256 (or 512)
> > nodes in MPP machines ?
> >
> > Sincerely,
> > Sunwoo
> >
> >
> > > From: "Marcus G. Daniels" <address@hidden>
> > > Reply-To: address@hidden
> > > Date: Thu, 29 Jan 2004 10:44:46 -0700
> > > To: address@hidden
> > > Subject: Re: [Swarm-Modelling] SWARM on Clusters
> > >
> > > Sunwoo Park wrote:
> > >
> > >
> > > > I just joined in this mailing list.
> > > > I have a simple question regarding SWARM software.
> > > > Is there any SWARM implementation that runs on cluster machines (or MPP
> > > > machines) based on Message Passing Paradigm (e.g., MPI) ?
> > >
> > > Swarm has a fine-grained knowledge of concurrency during a simulation.
> > > When multiple agents do something at the same timestep, Swarm knows
> > > this.   But that's just a little atom of the whole simulation execution
> > > sequence.  What this means is that in order for Swarm to exploit this
> > > knowledge on a parallel computer, it is necessary to be able to
> > > efficiently get that atom of computation to a physical processor.  A
> > > cluster, like a Beowulf arrangement of PCs, can't do this because the
> > > communication expense of getting the atom to the processor not amortized
> > > by the computation done.   A SMP or NUMA system can do this because the
> > > communication/overhead expense of getting the computation to the
> > > processor is small.  So if you have a two or four or eight way Opteron
> > > or Sun system or a big NUMA system like a SGI Altix, the interconnect
> > > between processors could reasonably slurp up these atoms and there would
> > > be a scalability win.
> > >
> > > I think it would be hard to make a message passing system scale very
> > > well based on an architecture like Swarm.   You'd need low-latency
> > > interconnect, maybe Myrinet.
> > >
> > > In any case, Swarm doesn't implement either.  A multithreaded Swarm
> > > would be feasible, but would assume a shared memory system like I 
> > > mentioned.
> > > _______________________________________________
> > > Modelling mailing list
> > > address@hidden
> > > http://www.swarm.org/mailman/listinfo/modelling
> >
> >
> > _______________________________________________
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--
Dr James A. R. Marshall
Department of Computer Science
University of Bristol
http://www.cs.bris.ac.uk/home/marshall