USENIX 2001 Abstract
Virtual-Time Round-Robin: An O(1) Proportional Share Scheduler
Jason Nieh, Chris Vaill, and Hua Zhong, Columbia University
Proportional share resource management provides a flexible and useful
abstraction for multiplexing time-shared resources. However, previous
proportional share mechanisms have either weak proportional sharing
accuracy or high scheduling overhead. We present Virtual-Time
Round-Robin (VTRR), a proportional share scheduler that can provide
good proportional sharing accuracy with O(1) scheduling overhead.
VTRR achieves this by combining the benefits of fair queueing
algorithms with a round-robin scheduling mechanism. Unlike many other
schedulers, VTRR is simple to implement. We have implemented a VTRR
CPU scheduler in Linux in less than 100 lines of code. Our performance
results demonstrate that VTRR provides accurate proportional share
allocation with constant, sub-microsecond scheduling overhead. The
scheduling overhead using VTRR is two orders of magnitude less than
the standard Linux scheduler for large numbers of clients.
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