Adaptive Disk Spin-Down Policies for Mobile Computers
نویسندگان
چکیده
Mobile computers typically spin down their hard disk after a fixed period of inactivity. If this threshold is too long, the disk wastes energy; if it is too short, the delay due to spinning the disk up again frushates the user. Usage patterns change over time, so a single fixed threshold may not be appropriate at all times. Also, different users may have varying priorities with respect to trading off energy conservation against performance. We describe a method for varying the spin-down threshold dynamically by adapting to the user's access patterns and priorities. Adaptive spin-down can in some circumstances reduce by up to 507o the number of disk spin-ups that are deemed by the user to be inconvenient, while only moderately increasing energy consumption. This is a revised version of a paper that appeared in the SeconÅ USENIX Symposium on Mobile and locationIndependent Computing, Awt Arbor, MI, pages l2l-137, April 1995. This work was performed in part at the Matsushita Information Technology Laboratory ofPanasonic Technologies, Inc. @ 1995 The USENIX Association, Computing Systems, Vol. 8 . No. 4 . Fall 1995 381
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