POWER MANAGEMENT FOR DIGITAL DEVICES

• US 20120110351A1
• Filed: 10/29/2010
• Published: 05/03/2012
• Est. Priority Date: 10/29/2010
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Raju, Veeramanikandan, Dandawate, Saket Sudhir, Nadampalli, Sunita, H., Sundara Raman
• Granted Patent: US 8,694,811 B2
• Time in Patent Office: Days
• US Class Current: 713/300
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: G06F 1/324 by lowering clock frequency
• CPC Class Codes: G06F 1/325 Power saving in peripheral device
• CPC Class Codes: G06F 1/3296 by lowering the supply or operating voltage
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

In a digital device, activity of (or load on) one or more processors, peripherals and memory buses are measured. A power management framework operated in the digital device bases power settings in the digital device on the measured loads, and accordingly issues power management commands to change power consumption states of one or more of the processors, peripherals and memory buses. Some user applications (termed power aware applications) in the digital device provide a number identifying their application type to the power management framework, which thereby determines the resources required by the application. The power management commands issued by the power management framework ensure provision of the corresponding resources to the application, while also targeting minimization of power consumption in the digital device. In an embodiment, the digital device corresponds to a mobile phone.

Claims

1. A method of managing power consumption in a digital device, the digital device comprising one or more processors, a peripheral component and a memory, wherein the peripheral component and the memory transfer data between each other on a bus using direct memory access (DMA), the method comprising:

determining a number of units of data transferred on the bus between the peripheral component and the memory in a prior time interval;

computing an estimate of a number of units of data that will be transferred on the memory bus in a future time interval; and

issuing a power management command to change a power consumption state of at least one of the one or more processors, the peripheral component and the memory, wherein the determination of the power management command includes the use of the estimate.

2. The method of claim 1, wherein the issuing a power management command is designed to change a value of at least one of a power supply voltage supplied to the one or more processors or the peripheral component, a frequency of a clock controlling the operations of the one or more processors or the peripheral component, and a frequency of a bus clock controlling a rate of transfer of data on the bus.

3. The method of claim 2, wherein the transfer of data on the bus is controlled by a bus controller, wherein the bus controller receives the bus clock, wherein the changing comprises writing a value to the bus controller to modify the frequency of the bus clock.

4. The method of claim 2, further comprising:

measuring an activity level of a first processor in the one or more processors in the prior time interval;

computing an estimate of an activity level of the first processor in the future time interval; and

adjusting either a value of a first power supply voltage supplied to the first processor or a frequency of a first clock controlling the operation of the first processor.

5. The method of claim 4, wherein the first processor is a co-processor optimized for performing digital signal processing, the one or more processors comprising a second processor for executing one or more user applications.

6. The method of claim 1, further comprises retrieving a value specifying a latency of a hardware resource in the digital device,

wherein the determination of the power management command includes the use of the latency.

7. The method of claim 1, wherein the digital device is a mobile phone, and wherein the one or more processors, the peripheral component, the memory and the bus controller are all fabricated in integrated circuit (IC) form on a system-on chip (SOC).

8. A non-transient machine readable medium storing one or more sequences of instructions for managing power consumption in a digital device, the non-transient machine readable medium comprising:

a first set of instructions constituting a power management framework;

a second set of instructions constituting a first application which when executed in the digital device is designed to send an identifier of the first application to the power management framework executing in the digital device;

the first set of instructions when executed in the digital device being designed to determine a resource requirement for executing the first application in the digital device, wherein the determining is performed based on the identifier received from the first application, and

to generate a set of power management commands to control power consumption in the digital device,

wherein the set of power management commands are designed to ensure the provision of the resource requirement to the first application.

9. The non-transient machine readable medium of claim 8, wherein the resource requirement includes at least one of a power supply voltage supplied to a component in the digital device, a frequency of a clock controlling the operations of the component, or a frequency of a bus clock controlling a rate of transfer of data on a bus coupled between the component and a memory contained in the digital device.

10. The non-transient machine readable medium of claim 9, wherein the to generate a set of power management commands comprises:

measuring, in a prior time interval, one or both of an activity level of the component, and a number of units of data transferred on the bus between the component and the memory; and

computing, for a future time interval, an estimate of the activity level of the component and a number of units of data that will be transferred on the bus;

wherein the set of power management commands adjusts one or both of a value of the power supply voltage supplied to the component and a frequency of the clock controlling the operations of the component.

11. The non-transient machine readable medium of claim 10, wherein the component is one of a processor, a peripheral and a memory.

12. The non-transient machine readable medium of claim 9, wherein the power management framework performs a first set of actions to generate the set of power management commands, wherein the first set of actions comprises:

determining a load on each of a plurality of components comprised in the digital device;

normalizing the load determined on each of the plurality of components;

computing a statistical measure of a set of past values and a current value for each of the normalized loads to obtain a set of processed load values; and

mapping the set of processed load values to a power management setting.

13. The non-transient machine readable medium of claim 12, wherein the mapping is one of a linear mapping and a non-linear mapping.

14. The non-transient machine readable medium of claim 13, wherein the linear mapping relates the set of processed load values and the power management setting in a linear fashion,

wherein, if processed load values have been increasing over a series of power management intervals including a current power management interval and a set of immediately previous and consecutive power management intervals, the linear mapping in the current interval selects a next higher power management setting.

15. The non-transient machine readable medium of claim 13, wherein the non-linear mapping relates the set of processed load values and the power management setting in a non-linear fashion,

wherein, if processed load values have been varying sporadically over a series of power management intervals including a current power management interval and a set of immediately previous and consecutive power management intervals, the non-linear mapping in the current interval selects the highest power management setting.

16. A method of determining a power management setting in a digital device, the method being performed by a power management framework operational in the digital device, the method comprising:

determining a load on each of a plurality of components comprised in the digital device;

normalizing the load determined on each of the plurality of components;

computing a statistical measure of a set of past values and a current value for each of the normalized loads to obtain a set of processed load values; and

mapping the set of processed load values are mapped to obtain the a power management setting,

wherein the mapping is one of a linear mapping and a non-linear mapping.

17. The method of claim 16, wherein the linear mapping relates the set of processed load values and the power management setting in a linear fashion,

wherein, if processed load values have been increasing over a series of power management intervals including a current power management interval and a set of immediately previous and consecutive power management intervals, the linear mapping in the current interval selects a next higher power management setting.

18. The non-transient machine readable medium of claim 16, wherein the non-linear mapping relates the set of processed load values and the power management setting in a non-linear fashion,

wherein, if processed load values have been varying sporadically over a series of power management intervals including a current power management interval and a set of immediately previous and consecutive power management intervals, the non-linear mapping in the current interval selects the highest power management setting.

19. A method of managing power consumption in a digital device, the digital device comprising one or more processors, a peripheral component and a memory, the one or more processors, the peripheral component and the memory communicating on a shared bus, the method comprising:

determining a load on each of the one or more processors, the peripheral and the shared bus in a prior time interval;

receiving, from an application to be executed in the digital device, an indication representing a resource requirement of the application;

computing a future load on at least one of the one or more processors, the peripheral and the shared bus, wherein the computing is based on both the determining and the receiving; and

issuing a power management command to change a power consumption state of at least one of the one or more processors, the peripheral and the shared bus.