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USENIX 2nd Symposium on
OS Design and Implementation (OSDI '96)
CPU Inheritance Scheduling
Bryan Ford and
Sai Susarla
University of Utah
Abstract
Traditional processor scheduling mechanisms in operating systems are
fairly rigid, often supporting only one fixed scheduling policy, or,
at most, a few ``scheduling classes'' whose implementations are
closely tied together in the OS kernel. This paper presents CPU
inheritance scheduling, a novel processor scheduling framework in
which arbitrary threads can act as schedulers for other threads.
Widely different scheduling policies can be implemented under the
framework, and many different policies can coexist in a single system,
providing much greater scheduling flexibility. Modular, hierarchical
control can be provided over the processor utilization of arbitrary
administrative domains, such as processes, jobs, users, and groups,
and the CPU resources consumed can be accounted for and attributed
accurately. Applications, as well as the OS, can implement customized
local scheduling policies; the framework ensures that all the
different policies work together logically and predictably. As a side
effect, the framework also cleanly addresses priority inversion by
providing a generalized form of priority inheritance that
automatically works within and among diverse scheduling policies. CPU
inheritance scheduling extends naturally to multiprocessors, and
supports processor management techniques such as processor
affinity[29] and scheduler activations[3]. We show that this
flexibility can be provided with acceptable overhead in typical
environments, depending on factors such as context switch speed and
frequency.
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