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Automatic Central Processing Unit Speed Control According to Operating System Idle Call Behavior

IP.com Disclosure Number: IPCOM000114799D
Original Publication Date: 1995-Feb-01
Included in the Prior Art Database: 2005-Mar-29
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Inui, T: AUTHOR [+2]

Abstract

Disclosed is a method to control the system Central Processing Unit (CPU) clock speed dynamically according to the Operating Systems (OS) idle call state used to stop the clock till the next hardware interrupts. This helps the system get the best performance for running applications and still keep the reduced power consumption by its dynamic CPU clock down.

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This is the abbreviated version, containing approximately 100% of the total text.

Automatic Central Processing Unit Speed Control According to Operating
System Idle Call Behavior

      Disclosed is a method to control the system Central Processing
Unit (CPU) clock speed dynamically according to the Operating Systems
(OS) idle call state used to stop the clock till the next hardware
interrupts.  This helps the system get the best performance for
running applications and still keep the reduced power consumption by
its dynamic CPU clock down.

The clock control policies are:
  1.  If the OS idle call routine is not called in a unit time, the
       clock speed is automatically up to the maximum speed.
  2.  If the OS idle call routine is frequently called in a unit
time,
       the clock speed is automatically down to the minimum speed.
  3.  In the system which has variable CPU clocks, Case 1 and 2, and
       the intermediate case are done consecutively.

      According to running applications, if the CPU spends most of
its time in the OS idle routine, it can run at the minimum speed
without any performance impact.  While it must run at the maximum
speed if it is required high speed memory operation.  The Figure
shows the example system counting the OS idle call and changing the
CPU clock by stepping.