Abstract - Technical Program - OSDI 99
A Feedback-driven Proportion Allocator for Real-Rate Scheduling
David C. Steere, Ashvin Goel, Joshua Gruenberg, Dylan McNamee, Calton Pu, Jonathan Walpole
Oregon Graduate Institute
In this paper we propose changing the decades-old practice of
allocating CPU to threads based on pri-ority to a scheme based on
proportion and period. Our scheme allocates to each thread a
percentage of CPU cycles over a period of time, and uses a
feedback-based adaptive scheduler to assign automatically both
proportion and period. Applications with known requirements, such as
isochronous software devices, can bypass the adaptive scheduler by
specifying their desired proportion and/or period. As a result, our
scheme provides reservations to applications that need them, and the
benefits of proportion and period to those that do not. Adaptive
scheduling using proportion and period has several distinct benefits
over either fixed or adaptive priority based schemes: finer grain
control of allocation, lower variance in the amount of cycles
allocated to a thread, and avoidance of accidental priority inversion
and starvation, including defense against denial-of-service attacks.
This paper describes our design of an adaptive controller and
proportion-period scheduler, its implementation in Linux, and presents
experimental validation of our approach.
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