Dual Processor Cluster Contention

Discussion
Found this on the cool Cluster Rant slash based Cluster site.

While the addition of a second CPU seems minimal from a cost perspective, it may lead to false sense of efficiency for the cluster. Indeed, the tests indicate that a program that normally takes 20 minutes on a single CPU node, may take as long as 40 minutes on an active dual CPU node. This situation may be further compounded by the fact that the batch scheduler may place a program on the first or second processor of any node and thus provide the program with a very heterogeneous memory contention environment. (i.e. some nodes may have large memory contention and other may have none.)