Optimising heterogeneous task migration in the Gardens virtual cluster computer

Gardens is an integrated programming language and system designed to support parallel computing across nondedicated cluster computers, in particular networks of PCs. To utilise non-dedicated machines a program must adapt to those currently available. In Gardens this is realised by over decomposing a program into more tasks than processors, and migrating tasks to implement adaptation. To be effective this requires efficient task migration. Furthermore, typically non-dedicated clusters contain different machines hence heterogeneous task migration is required. Gardens supports efficient task migration between heterogeneous machines via meta-information which completely describes a task's state. By identifying different degrees of heterogeneity and different kinds of tasks, we are able to optimise task migration. The main contribution is to show how heterogeneous task migration may be optimised.