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Subject: Re: [OMPI users] Optimal distribution of low and high CPU processes on a heterogeneous cluster
From: Alberto Giannetti (albertogiannetti_at_[hidden])
Date: 2008-04-26 17:41:36

Check the FAQ section for processor affinity.

On Apr 25, 2008, at 2:27 PM, Roopesh Ojha wrote:
> Hello
> As a newcomer to the world of openMPI who has perused the faq and
> searched
> the archives, I have a few questions about how to schedule processes
> across
> a heterogeneous cluster where some processes must be bound to
> particular
> nodes and where some processes will not be compute bound, meaning more
> processes than CPU cores is likely desired. Allow me to first
> describe our
> situation and then ask some specific questions.
> We have a cluster of four nodes/hosts. Two of these have a single
> Pentium3
> 0.8GHz processor each. The other two have dual core processors. Our
> data
> resides on two external drives that are mounted on the two fast
> machines
> but are visible to all nodes over nfs. Our setup is not a real
> cluster in
> the sense that we are using ssh over nfs to link our nodes.
> For our application, some processes (manager and the datastreams)
> won't
> take much CPU power while others will. Our application first
> assigns the
> non-compute bound processes and then the high CPU power ones.
> Clearly we
> would like to be able to assign the former processes to our two slower
> machines. How can we get MPI to achieve this? What is the best way to
> use
> slot and max-slot commands in the hostfile to optimize performance?
> How
> does max-slot behave when some node is listed more than once in the
> hostfile?
> Is there any way to control where processes are deployed apart from
> the
> basic bynode or byslot round robin schedule?
> Many thanks for your time.
> Regards
> Roo
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