Tickets and currencies revisited: extensions to multi-resource lottery scheduling

Lottery scheduling's ticket and currency abstractions provide a resource management framework that allows for both flexible allocation and insulation between groups of processes. We propose extensions to this framework that enable greater flexibility while preserving the ability to isolate groups of processes. In particular we present a mechanism that allows processes to modify their own resource rights by exchanging resource-specific tickets with other processes. Ticket exchanges limit the effects of the changed allocations to the participants in the exchange, and they allow applications to coordinate with each other in ways that are mutually beneficial. Application-specific "negotiators" can be used to initiate exchanges based on an application's quality-of-service requirements and the current state of the system. We also propose flexible access controls for currencies through extensible "brokers" that solve such problems as the inability of users isolated by currencies to renice background jobs. Finally we suggest using extensibility to allow users to install specialized allocation mechanisms for their processes. Together these extensions enable an application-centered approach to resource management that is both secure and effective.