Delay-Cost Scheduling for Multithreaded, Multicore Machines

We outline a generalization of the delay-cost objective function approach employed in the IBM System I scheduler to systems with possibly large numbers of multithreaded machines. We concentrate on hypervisor scheduling of guest operating systems, although some discussion is included of OS scheduling in such systems, and the results may be applicable in larger contexts, such as management of computer installations. Two main differences between the issues treated here and current schedulers are a) the inclusion of coscheduling of multiple logical processors associated with a guest OS, and b) the inclusion of multiple ways to satisfy a request for logical processing resources, with different utilizations of hardware threads and electrical power as a function of the application. A generalized delay-cost objective function is described, as well as two versions of, or approaches to optimality, respectively the maximization of the objective function, and maximization of this function subject to a fairness criterion. Allocation of resources to jobs is done in two phases: first an amount is determined, and secondly this is matched with physical entities. The report includes a development and discussion of the generalized delay-cost function, the algorithms used in scheduling, as well as a variety of experimental results which suggest that the overall approach is reasonable, since both the speed of execution, as well as the system power utilization, can depend on the number and identity of the system resources utilized by specific applications.

By: Peter A. Franaszek; Dan E. Poff

Published in: RC24167 in 2007


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