Power Management System Incorporating Device Handshaking to Monitor User Activity
Original Publication Date: 1997-Sep-01
Included in the Prior Art Database: 2005-Apr-01
AbstractDisclosed is a power management software system that provides for the optimal monitoring of user-input device activity in a computer system. Status polling, power event, and power state mechanisms are combined to provide a superior solution for integrating user-input peripherals into the power management system.
Power Management System Incorporating Device Handshaking
a power management software system that provides
for the optimal monitoring of user-input device activity in a
computer system. Status polling, power event, and power state
mechanisms are combined to provide a superior solution for
integrating user-input peripherals into the power management system.
function of computer power management systems is to
monitor user-input peripheral devices for instances of activity and
periods of idleness so that power-saving system states are entered
and exited in a manner that minimizes average energy dissipation
while maximizing software performance. There are three aspects to
monitoring user-input devices:
1. Monitoring a set of devices for idleness. Power management
uses this kind of monitoring when the system is operating
in the highest system power state, and so it is looking for
an opportunity to conserve energy (by moving to a more
2. Monitoring a set of devices for both activity and idleness.
This type of monitoring occurs when the system operates in
any middle system power state. User activity leads power
management to implement transitions to higher, or less
conserving power states, while periods of idleness lead
to transitions to lower, or more conserving, power states.
3. Monitoring a set of devices for activity. This type of
monitoring occurs in the lowest, most energy conserving
state. The first instance of user activity leads power
management software to implement a transition to an active
system power state.
of monitoring user-input devices for the purpose of
power management has traditionally been solved by implementing one of
1. A central power management facility that periodically polls
user-input device status. Polls for idleness have a low
frequency, while polls or activity have a high frequency.
2. Participatory user-input device drivers that generate and
communicate power events based on the activity and idleness
of their device.
method alone provides an optimal solution for all three
aspects of device monitoring. The polling method is non-optimal for
activity monitoring since there is a latency between polls, and a
high-frequency poll reduces software performance. The event method
is non-optimal for idleness monitoring, since the generation of a
power event for every instance of device activity can seriously
degrade software performance.
described herein combines the poll and event methods
and adds a power-state control method, or handshake, in order to
provide an optimal solution for each aspect of user-inp...