com.digi.android.system.cpu

Class GovernorConservative

java.lang.Object

com.digi.android.system.cpu.Governor

com.digi.android.system.cpu.GovernorCommonBase

com.digi.android.system.cpu.GovernorConservative

public class GovernorConservative
extends GovernorCommonBase

Represents a governor of type 'conservative'. This governor is very similar to the 'ondemand' one, sets the CPU depending on the current usage. It differs in behavior in that it gracefully increases and decreases the CPU speed rather than jumping to max speed at the moment there is any load on the CPU. This behavior is more suitable in a battery powered environment.

Like the 'ondemand' one, this governor extends the GovernorCommonBase and includes some other parameters that can be configured.

Field Summary

Fields

Modifier and Type	Field and Description
static int	MAX_SAMPLING_DOWN_FACTOR Maximum sampling down factor: 10.
static int	MIN_DOWN_THRESHOLD Minimum down threshold: 11.

Fields inherited from class com.digi.android.system.cpu.GovernorCommonBase

MAX_SAMPLING_RATE

Fields inherited from class com.digi.android.system.cpu.Governor

governorType, handler, PATH_GOVERNOR_SETTINGS

Method Summary

Modifier and Type	Method and Description
int	getDownThreshold() Gets the down threshold percentage.
int	getFreqStep() Gets the frequency step percentage.
protected int	getSamplingDownFactorMaxValue() Returns the maximum limit for the sampling down factor.
protected java.lang.String	getTag() Returns the class tag used for logging purposes.
protected int	getUpThresholdMinValue() Returns the minimum limit for the up threshold percentage.
void	setDownThreshold(int threshold) Sets the down threshold percentage.
void	setFreqStep(int frequency) Sets the frequency step percentage.
void	setSamplingDownFactor(int factor) Sets the sampling down factor.
void	setUpThreshold(int threshold) Sets the up threshold percentage.

Methods inherited from class com.digi.android.system.cpu.GovernorCommonBase

disableIgnoreNiceLoad, enableIgnoreNiceLoad, getIgnoreNiceLoad, getMinSamplingRate, getSamplingDownFactor, getSamplingRate, getUpThreshold, setSamplingRate

Methods inherited from class com.digi.android.system.cpu.Governor

getGovernorType, getSettingPath, readFile, writeFile

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

MIN_DOWN_THRESHOLD

public static final int MIN_DOWN_THRESHOLD

Minimum down threshold: 11.

See Also:

Constant Field Values

MAX_SAMPLING_DOWN_FACTOR

public static final int MAX_SAMPLING_DOWN_FACTOR

Maximum sampling down factor: 10.

See Also:

Constant Field Values

Method Detail

getTag

protected java.lang.String getTag()

Description copied from class: Governor

Returns the class tag used for logging purposes.

Specified by:

getTag in class Governor

Returns:

The class tag.

setUpThreshold

public void setUpThreshold(int threshold)
                    throws CPUException

Sets the up threshold percentage. Defines what the average CPU usage between the samplings of 'Sampling rate' needs to be for the kernel to make a decision on whether it should increase the frequency.

For example when it is set to its default value of '95' it means that between the checking intervals the CPU needs to be on average more than 95% in use to then decide that the CPU frequency needs to be increased.

Overrides:

setUpThreshold in class GovernorCommonBase

Parameters:

threshold - The up threshold percentage.

Throws:

CPUException - If there is an error during the configuration process.

java.lang.IllegalArgumentException - If threshold <= getDownThreshold() or if threshold > 100.

See Also:

getDownThreshold(), GovernorCommonBase.getUpThreshold()

setSamplingDownFactor

public void setSamplingDownFactor(int factor)
                           throws CPUException

Sets the sampling down factor. This parameter controls the rate at which the kernel makes a decision on when to decrease the frequency while running at top speed. When set to 1 (the default) decisions to reevaluate load are made at the same interval regardless of current clock speed. But when set to greater than 1 (e.g. 10) it acts as a multiplier for the scheduling interval for reevaluating load when the CPU is at its top speed due to high load.

Overrides:

setSamplingDownFactor in class GovernorCommonBase

Parameters:

factor - The new sampling down factor.

Throws:

CPUException - If there is an error during the configuration process.

java.lang.IllegalArgumentException - If factor < 1 or if factor > MAX_SAMPLING_DOWN_FACTOR.

See Also:

MAX_SAMPLING_DOWN_FACTOR, GovernorCommonBase.getSamplingDownFactor()

setDownThreshold

public void setDownThreshold(int threshold)
                      throws CPUException

Sets the down threshold percentage. Defines what the average CPU usage between the samplings of 'sampling_rate' needs to be for the kernel to make a decision on whether it should decrease the frequency.

For example when it is set to its default value of '20' it means that the CPU usage needs to be below 20% between samples to have the frequency decreased.

Parameters:

threshold - The down threshold percentage.

Throws:

CPUException - If there is an error during the configuration process.

java.lang.IllegalArgumentException - If threshold < MIN_DOWN_THRESHOLD or if threshold >= getUpThreshold().

See Also:

MIN_DOWN_THRESHOLD, getDownThreshold(), GovernorCommonBase.getUpThreshold()

getDownThreshold

public int getDownThreshold()
                     throws CPUException

Gets the down threshold percentage. Gets the average CPU usage between the samplings of 'sampling_rate' needs to be for the kernel to make a decision on whether it should decrease the frequency.

Returns:

The down threshold percentage, -1 if the value could not be read.

Throws:

CPUException - If there is an error during the configuration process.

See Also:

setDownThreshold(int)

setFreqStep

public void setFreqStep(int frequency)
                 throws CPUException

Sets the frequency step percentage. This describes what percentage steps the CPU frequency should be increased and decreased smoothly by. By default the CPU frequency will increase in 5% chunks of your maximum CPU frequency.

You can change this value to anywhere between 0 and 100 where '0' will effectively lock your CPU at a speed regardless of its load whilst '100' will, in theory, make it behave identically to the 'ondemand' governor.

Parameters:

frequency - The new frequency step percentage.

Throws:

CPUException - If there is an error during the configuration process.

java.lang.IllegalArgumentException - If frequency < 0 or if frequency > 100.

See Also:

getFreqStep()

getFreqStep

public int getFreqStep()
                throws CPUException

Gets the frequency step percentage. This describes what percentage steps the CPU frequency should be increased and decreased smoothly by. '0' means that the CPU speed is locked at a speed regardless of its load and '100' makes it behave identically to the 'ondemand' governor.

Returns:

The frequency step percentage, -1 if the value could not be read.

Throws:

CPUException - If there is an error during the configuration process.

See Also:

setFreqStep(int)

getSamplingDownFactorMaxValue

protected int getSamplingDownFactorMaxValue()

Description copied from class: GovernorCommonBase

Returns the maximum limit for the sampling down factor.

Specified by:

getSamplingDownFactorMaxValue in class GovernorCommonBase

Returns:

the maximum limit for the sampling down factor.

getUpThresholdMinValue

protected int getUpThresholdMinValue()
                              throws CPUException

Description copied from class: GovernorCommonBase

Returns the minimum limit for the up threshold percentage.

Specified by:

getUpThresholdMinValue in class GovernorCommonBase

Returns:

the minimum limit for the up threshold.

Throws:

CPUException - If there is an error while calculating the minimum limit.