Unlock instant, AI-driven research and patent intelligence for your innovation.

Demand-based method and system of CPU power management

a demand-based method and power management technology, applied in the field of central processing units (cpus), can solve the problems of reducing the number of operations or tasks that the device can perform, limiting the maximum frequency at which the device may be operated, and inactive or unused devices,

Inactive Publication Date: 2005-05-19
COOPER BARNES +1
View PDF29 Cites 12 Cited by
  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

"The present invention is a method and system for managing the power consumption of central processing units (CPUs) in battery-dependent portable computing devices. The invention is based on a demand-based approach, which means that the CPU power management is triggered when the device is actively being used, as opposed to a pre-defined power mode. The invention looks to both the voltage and frequency of the CPU to determine the optimal way to save power. The invention also takes into account the current utilization of the device, which is determined by the number of tasks or threads that are ready to run. The invention provides a more user-transparent and effective way to manage CPU power consumption in battery-dependent devices."

Problems solved by technology

This method however, requires that the devices powered down be inactive or unused for a sufficiently long period of time to justify the latency associated with their re-activation.
Such voltage reduction techniques also currently limit the maximum frequency at which a device may be operated.
Although these approaches may be used alone or in combination to reduce a device's or system's power consumption, this frequency scaling technique reduces the operating frequency of the device, and consequently the number of operations or tasks it can perform.
The greatest difficulty traditionally associated with such demand-based systems has been in determining a device's current utilization, particularly for processing devices such as the central processing unit (CPU) of a data processing system.
Unfortunately, neither this measure of CPU utilization nor the state of the ready-to-run task list is available outside of the OS through a supported application programming interface (API).
Consequently, this OS-generated CPU utilization metric cannot be utilized in a “demand” or utilization-based power management system.

Method used

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Image

Smart Image Click on the blue labels to locate them in the text.
Viewing Examples
Smart Image
  • Demand-based method and system of CPU power management
  • Demand-based method and system of CPU power management
  • Demand-based method and system of CPU power management

Examples

Experimental program
Comparison scheme
Effect test

first embodiment

[0026] Referring now to FIG. 4, a high-level logic flowchart of the method of the present invention is illustrated. In FIG. 4 there is depicted a technique by which a demand-based transition between two processor performance states is executed. At block 400, the illustrated process is begun and thereafter a CPU utilization status request is received from a power management application (block 402). The described utilization request may be periodic or may occur in response to relevant power management events such as thermal or processor workload events, the connection of an alternating current power supply or the like. Once the CPU utilization has been established (block 404), a determination is then made whether the calculated utilization exceeds a utilization threshold (block 406). In the illustrated embodiment, a relatively high utilization threshold of 95% is selected to identify the execution of demand-intensive applications such as DVD movie players, personal computer games, and...

second embodiment

[0028] Referring now to FIG. 5, a high-level logic flowchart of the method of the present invention is illustrated. After the process is begun (block 500) a user-specified power management profile is received (block 502) in which power conservation and system performance are prioritized generally or a specific, preferred processor performance mode may be designated. In the illustrated embodiment, a maximum battery or ultra battery optimized profile is received conveying that power conservation is to be favored over execution speed. Then an executing power management software or firmware application generates a system management interrupt (SMI) (block 504) in response to the receipt of the user power management profile which in turn transitions the CPU to battery optimized mode if necessary from whatever prior state the processor was operating in. Subsequently, the power management application issues a request for the current CPU utilization status (block 508) which is determined eit...

third embodiment

[0030] Referring now to FIG. 6, a high-level logic flowchart of the method of the present invention is illustrated. The beginning of the process is depicted at block 600 and thereafter a CPU utilization status request is received from a power management application (block 602). Once the CPU utilization has been established (block 604), a determination is made whether the calculated utilization exceeds a utilization threshold (block 606). In the illustrated embodiment, a relatively high utilization threshold of 95% is selected for this first utilization threshold as illustrated. If the utilization threshold is exceeded, any previously applied CPU clock signal throttling is disabled (block 608) and the CPU is transitioned to a maximum performance processor performance mode (block 610) and operated at a higher performance level to ensure that the execution performance of demand-intensive application programs is not degraded.

[0031] If the utilization of the CPU is not above or equal to ...

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

PUM

No PUM Login to View More

Abstract

A demand-based method and system of central processing unit power management. The utilization of a central processing unit (CPU) during a sampling time interval is determined by measuring a time quantum within the sampling time interval during which a central processing unit clock signal is active within a processor core of the CPU. The total number of cycles of the central processing unit clock signal that are applied to the processor core and the period of the central processing unit clock signal are used to determine the time quantum. The utilization may then be expressed in terms of a ratio of the time quantum to the total time interval and used to select a processor performance mode. The CPU is then operated in the selected processor performance mode.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS [0001] This application is a continuation of U.S. patent application Ser. No. 09 / 751,759 entitled “Demand-Based Method and System of CPU Power Management,” assigned to the assignee of the present invention and filed Dec. 30, 2000.FIELD OF THE INVENTION [0002] The field of the invention relates generally to central processing units (CPUs). More particularly the field invention relates to CPU power management. Still more particularly, the field of the invention relates to a demand-based method and system of CPU power management. BACKGROUND OF THE INVENTION [0003] As battery-dependent portable computing devices (notebook computers, personal digital assistants, etc.) have become more prevalent, the conservation of battery power or “power management” has become more and more important. In many power management systems, some or all system components may be deactivated or “powered down” to conserve power. This method however, requires that the device...

Claims

the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to View More

Application Information

Patent Timeline
no application Login to View More
Patent Type & Authority Applications(United States)
IPC IPC(8): G06F1/32
CPCG06F1/3203Y02B60/1221G06F1/3237Y02D10/00
Inventor COOPER, BARNESARJANGRAD, JAY
Owner COOPER BARNES