[Beowulf] 1 multicore machine cluster

Jonathan Aquilina eagles051387 at gmail.com
Sat May 2 04:40:28 EDT 2009


well the term leaf node is already used in the irc environment. also
couldnt one consider a core on a multicore processor a node as well or
not since its using share resources for one processor?

On 4/30/09, Peter St. John <peter.st.john at gmail.com> wrote:
> I think (as I've said before, sorry if I'm banging a drum) that the new idea
> of "node" is going to be relative, and we will end up with more elementary
> concepts. To a trivially distributed, compute intenstive application (like,
> crunching a long time to factor one big integer), a node would be just an
> independent hyperthread within a core. To a latency intensive, message
> passing appliation, like the N body problem or weather forecasting, a node
> would be something with it's own NIC, like a motherboard level, not a single
> core.
>
> I believe that sooner or later applications will be smart and adaptable
> about it, and request different kinds of nodes for different kinds of tasks.
> So we will have terms like:
>
> fat node -- has it's own NIC and disks.
> fast node -- has a fast connection, maybe faster than most nodes on the
> cluster, 100GigE whatever.
> thread node -- the node for a compute intensive app.
> leaf node -- relative; maybe fat for some apps, threads for others.
> etc.
>
> Every since coining the term "groupie" (for a node that has few neighbors,
> but is connected to nodes with lots of neighbors) which got into the
> literature (graph theory) I've been ambitious about this sort of thing :-)
>
> Peter
>
> P.S. the mathematician Leonard Carlitz (I wrote his wiki entry) taught me by
> example how much better you work when you group terms into the right level
> of abstraction. You think as efficiently as the concepts are appropriately
> loaded in your brain, with handles. Like OO programming except back then it
> was grouping algebraic terms on paper :-)
>
>
>
> On 4/29/09, Mark Hahn <hahn at mcmaster.ca> wrote:
>>
>> I think the term ´nodeĄ is a loaded term in HPC.  This is what comes
>>>>
>>>
>> I think it's just a bit sloppy or at least contextual - I've never
>> heard it used for anything other than "box".  a node on a conventional
>> message-passing cluster is clearly one computer, which may contain
>> multiple
>> cores, but has a single memory domain.  on an Origin/Altix,
>> people seem to prefer "brick", but sometimes use "node", and is obviously
>> not a single memory domain.  MPI programmers usually use "rank" or
>> "processor", and don't get hung up on nodes.
>>
>>  There is an awful lot of software around which refers to "nodes" when in
>>> your nomenclature it means core[1], most of it harks back to when nodes
>>>
>>
>> hmm, a contrary example is gromacs - it explicitly talks about nodes
>> but permits threads within a node.  ie, an 8-core box could be a single
>> node with 8 threads or 8 nodes, 1th each.
>>
>> incidentally, any gromacs experts comment on scalability of using the
>> thread support?  (ie, for four 8c boxes with IB, 32 nodes vs 4 nodes, 8
>> threads each?)
>>
>>  had one CPU and a CPU had one core.  Even the concept of cores
>>> themselves are only six or seven years old, before then a CPU was just a
>>> CPU and you would refer to "a N CPU cluster".
>>>
>>
>> and to be on the safe side (wrt forms of simultaneous multi-threading),
>> we should probably try to use "thread" instead.  meaning a single hardware
>> execution context.
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-- 
Jonathan Aquilina

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