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Department of Computer Science 4
Cooperative IO
Dept. of Computer Science  >  CS 4  >  Research  >  PowerManagement  >  Projects  >  Energy-Aware I/O
Cooperative I/O
We demonstrate the benefits of application involvement in operating system power management. We present Coop-I/O, an approach to reduce the power consumption of devices while encompassing all levels of the system-from the hardware and OS to a new interface for cooperative I/O that can be used by energy-aware applications.
We assume devices which can be set to low-power operation modes if they are not accessed and where switching between modes consumes additional energy, e.g. devices with rotating components or network devices consuming energy for the establishment and shutdown of network connections. In these cases frequent mode switches should be avoided.
With Coop-I/O, applications can declare open, read and write operations as deferrable and even abortable by specifying a time-out and a cancel flag. This information enables the operating system to delay and batch requests so that the number of power mode switches is reduced and the device can be kept longer in a low-power mode.
We will show that in many cases Coop-I/O even outperforms the "oracle" shutdown policy which defines the lower bound in power consumption if the timing of requests can not be influenced.
Cooperative IO - A Novel IO Semantics for Energy-Aware Applications
Andreas Weissel, Björn Beutel, Frank Bellosa
Proceedings of the Fifth Symposium on Operating Systems Design and Implementation (OSDI '02), Boston, MA,
December 2002
[Abstract] [Full Paper (pdf), 353 kB]

Wireless Network Power Management
This approach identifies on-line the currently running application class by a mapping of network traffic characteristics to a predefined set of application profiles.
We propose a power saving policy which dynamically adapts the sleep interval of an IEEE 802.11 network interface to the detected application profile according to application- and user-specific power/performance demands.

Application Characterization for Wireless Network Power Management
Andreas Weissel, Matthias Faerber, Frank Bellosa
Proceedings of the International Conference on Architecture of Computing Systems (ARCS'04), Augsburg, Germany,
March 2004
[Abstract] [Full Paper (pdf), 385 kB] (c) Springer-Verlag
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