Summary: Robust, Portable I/O Scheduling with the Disk Mimic
Florentina I. Popovici, Andrea C. Arpaci­Dusseau, and Remzi H. Arpaci­Dusseau
Computer Sciences Department, University of Wisconsin, Madison
Abstract
We propose a new approach for I/O scheduling that per­
forms on­line simulation of the underlying disk. When
simulation is integrated within a system, three key chal­
lenges must be addressed: first, the simulator must be
portable across the full range of devices; second, all con­
figuration must be automatic; third, the computation and
memory overheads must be low. Our simulator, the Disk
Mimic, achieves these goals by building a table­based
model of the disk as it observes the times for previous
requests. We show that a shortest­mimicked­time­first
(SMTF) scheduler performs nearly as well as an approach
with perfect knowledge of the underlying device and that
it is superior to traditional scheduling algorithms such as
C­LOOK and SSTF; our results hold as the seek and ro­
tational characteristics of the disk are varied.
1 Introduction

Source: Arpaci-Dusseau, Remzi - Department of Computer Sciences, Department of Computer Sciences, University of Wisconsin at Madison
Liblit, Ben - Department of Computer Sciences, University of Wisconsin at Madison

Collections: Computer Technologies and Information Sciences