It is becoming increasingly commonplace for multiple applications with different quality of service (QoS) requirements to share the resources of a distributed system. Within this environment, the resource management algorithms must take into account the QoS desired by applications and the ability of the system resources to provide it. We present a taxonomy for specifying QoS for the different components of a distributed system, from the applications down to the resources. We specify QoS as a combination of metrics and policies. QoS metrics are used to specify performance parameters, security requirements and the relative importance of the work in the system. We define three types of QoS performance parameters: timeliness, precision, and accuracy. QoS policies capture application-specific policies that govern how an application is treated by the resource manager. Examples of such policies are management policies and the levels of service. We explore each of these components of the QoS taxonomy in detail.
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