[Beowulf] shared distributed memory ?

Douglas Eadline, Cluster World Magazine deadline at linux-mag.com
Thu Feb 26 19:01:51 EST 2004



A few questions:

What are your processor speeds?

What is your interconnect?

What is your application?

Having to communicate with another node vs the same node
is not the same thing. (ping local host and ping the other
node) Obviously your application is sensitive to the interconnect
(either bandwidth of latency)

Really fast processors and a slow interconnect usually means poor
scalability for some applications. 

Doug

On Wed, 25 Feb 2004, choy hau yan wrote:

> I am a user for scyld beowulf cluster. I use mpi  for
> parallel computing.I have some question:
> 
> > I got 2 processors that in shared memory and then
> > connect with TCP/IP to another 2 processors in
> shared
> > memory.
> >
> > I use mpisend/recv for communication, but why can't
> I
> > call this shared distributed memory?
> > The speedup with this architecture is very low.why?
> >
> > speedup:
> > 2 processor: 1.61
> > 3 processor: 2.31
> > 4 processor: 2.30
> > actually with shared memory, the speedup is more
> high
> > that distributed becasue almost no cos communication
> > in shared memory.right? Hope that some one can
> answer my question. thanks..
> >
> 
> 
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