On Tue, 2008-08-12 at 12:09 -0600, Craig Tierney wrote: > Chris Samuel wrote: > > ----- "I Kozin (Igor)" <[EMAIL PROTECTED]> wrote:
> > But that assumes you're not sharing a node with other > > jobs that may well be doing I/O. > > > I am wondering, who shares nodes in cluster systems with > MPI codes? In my experience, almost everyone. In practise though most jobs ask for even numbers of CPU's so larger jobs rarely get scheduled this way. > We never have shared nodes for codes that need > multiple cores since be built our first SMP cluster > in 2001. The contention for shared resources (like memory > bandwidth and disk IO) would lead to unpredictable code performance. Unpredictable maybe but if the alternative is to not run at all then it's still a win. What you wouldn't want is to have a small number of processes in a big job sharing a node with a resource hogging job and slow down the entire big job however I've never seen this happening in the wild. > Also, a poorly behaved program can cause the other codes on > that node to crash (which we don't want). It goes without saying that this shouldn't be able to happen. Ashley. _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
