[GE users] SGE and Shared Memory

Reuti reuti at staff.uni-marburg.de
Fri Jan 14 08:21:09 GMT 2005


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Hi,

> This is my first day to hear about SGE, sounds
> great. But I just wondering, 
> is the SGE can support software based shared memory?
> 
> In details, say I have 4 PC, each got 1 CPU. If they
> are managed by SGE, can 
> I run my OpenMP program with 4 processors?  That
> means SGE will manage them 
> as one PC with 4 CPU. If not, any other such
> solution?

OpenMP is bound to one machine to use threads and works on the same memory 
area. SGE will not join the memory or system bus to give you the illusion of 
just one machine with shared memory. You are thinking of a hardware solution as 
it is available e.g. on some SGI machines, where you have a special cable 
between the nodes and the whole bunch of machines suddenly appears to be one 
machine only, but with (in your case) 4 CPUs.

Parallel applications are supported if you switch to e.g. MPICH, PVM, Linda, 
GlobalArrays, OpenMPI [not related to OpenMP](which all handle the network 
communication for you); but you would have to rewrite your programs. OpenMP can 
still be used with SGE, if you have a machine with real shared memory.

BTW: There is s free 4 CPU Linda version for Linux C programming.

Cheers - Reuti

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