Added in API level 31

Session

class Session : Closeable
kotlin.Any
   ↳ android.os.PerformanceHintManager.Session

A Session represents a group of threads with an inter-related workload such that hints for their performance should be considered as a unit. The threads in a given session should be long-lived and not created or destroyed dynamically. The work duration API can be used with periodic workloads to dynamically adjust thread performance and keep the work on schedule while optimizing the available power budget. When using the work duration API, the starting target duration should be specified while creating the session, but can later be adjusted with updateTargetWorkDuration(long). While using the work duration API, the client is be expected to call reportActualWorkDuration(long) each cycle to report the actual time taken to complete to the system. Any call in this class will change its internal data, so you must do your own thread safety to protect from racing. All timings should be in SystemClock#uptimeNanos().

Summary

Public methods
open Unit

Ends the current hint session.

open Unit
reportActualWorkDuration(actualDurationNanos: Long)

Reports the actual duration for the last cycle of work.

open Unit

Reports the work duration for the last cycle of work.

open Unit

This tells the session that these threads can be safely scheduled to prefer power efficiency over performance.

open Unit

Set a list of threads to the performance hint session.

open Unit
updateTargetWorkDuration(targetDurationNanos: Long)

Updates this session's target total duration for each cycle of work.

Public methods

close

Added in API level 31
open fun close(): Unit

Ends the current hint session. Once called, you should not call anything else on this object.

Exceptions
java.lang.Exception if this resource cannot be closed
java.io.IOException if an I/O error occurs

reportActualWorkDuration

Added in API level 31
open fun reportActualWorkDuration(actualDurationNanos: Long): Unit

Reports the actual duration for the last cycle of work. The system will attempt to adjust the core placement of the threads within the thread group and/or the frequency of the core on which they are run to bring the actual duration close to the target duration.

Parameters
actualDurationNanos Long: how long the thread group took to complete its last task in nanoseconds

reportActualWorkDuration

open fun reportActualWorkDuration(workDuration: WorkDuration): Unit

Reports the work duration for the last cycle of work. The system will attempt to adjust the core placement of the threads within the thread group and/or the frequency of the core on which they are run to bring the actual duration close to the target duration.

Parameters
workDuration WorkDuration: the work duration of each component. This value cannot be null.
Exceptions
java.lang.IllegalArgumentException if work period start timestamp is not positive, or actual total duration is not positive, or actual CPU duration is not positive, or actual GPU duration is negative.

setPreferPowerEfficiency

open fun setPreferPowerEfficiency(enabled: Boolean): Unit

This tells the session that these threads can be safely scheduled to prefer power efficiency over performance.

Parameters
enabled Boolean: The flag that sets whether this session uses power-efficient scheduling.

setThreads

Added in API level 34
open fun setThreads(tids: IntArray): Unit

Set a list of threads to the performance hint session. This operation will replace the current list of threads with the given list of threads. Note that this is not an oneway method.

Parameters
tids IntArray: The list of threads to be associated with this session. They must be part of this app's thread group This value cannot be null.
Exceptions
java.lang.IllegalStateException if the hint session is not in the foreground
java.lang.IllegalArgumentException if the thread id list is empty
java.lang.SecurityException if any thread id doesn't belong to the application

updateTargetWorkDuration

Added in API level 31
open fun updateTargetWorkDuration(targetDurationNanos: Long): Unit

Updates this session's target total duration for each cycle of work.

Parameters
targetDurationNanos Long: the new desired duration in nanoseconds