Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Processor Shutdown in a Battery Powered System during Idle

IP.com Disclosure Number: IPCOM000113641D
Original Publication Date: 1994-Sep-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Christopher, KW: AUTHOR [+4]

Abstract

Described is the use of the HALT instruction (or WAIT instruction in some processor architectures) in the idle detection logic of the scheduler in an operating system within a battery powered computing system, such as a portable, palmtop, or laptop computer. This instruction can be placed at any point where interrupts are not blocked. After the processor is shut down in this way, normal execution can be started again using an interrupt, such as a timer interrupt.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 65% of the total text.

Processor Shutdown in a Battery Powered System during Idle

      Described is the use of the HALT instruction (or WAIT
instruction in some processor architectures) in the idle detection
logic of the scheduler in an operating system within a battery
powered computing system, such as a portable, palmtop, or laptop
computer.  This instruction can be placed at any point where
interrupts are not blocked.  After the processor is shut down in this
way, normal execution can be started again using an interrupt, such
as a timer interrupt.

      The use of the HALT or WAIT instruction contrasts with the use
of a polling technique, looking for the next service request while
the system is waiting at the command line prompt or at the command
menu of an application.  This polling technique consists of a tight
loop looking for the next input entered by the user.  Having the
processor execute continuously in such an idle loop causes an
unnecessary drain of battery power.

      A user-interactive computer system is normally in an idle mode,
during, for example, the time a user is thinking between commands or
pausing between keystrokes, and during the time an application is in
a suspended state waiting for an I/O operation to be completed or for
an interrupt to occur.  While some operating systems perform
housekeeping work during idle time, the accumulative idle time,
during which no useful work is accomplished, is typically quite
large.

      Thus, this use of the HAL...