Advanced Configuration and Power Interface Specification

Advanced Configuration and Power Interface Specification
Return Value:
A variable-length Package containing a list of Tstate sub-packages as described below
Return Value Information
Package {
TState [0] // Package – Throttling state 0
….
TState [n]
// Package – Throttling state n
}
Each Tstate sub-Package contains the elements described below:
Package {
Percent
Power
Latency
Control
Status
}
// Integer (DWORD)
// Integer (DWORD)
// Integer (DWORD)
// Integer (DWORD)
// Integer (DWORD)
Table 8-245 TState Package Values
Element Object Type Description
Percent Integer
(DWORD)
Indicates the percent of the core CPU operating frequency that will be available
when this throttling state is invoked. The range for this field is 1-100. This
percentage applies independent of the processor’s performance state (P-state).
That is, this throttling state will invoke the percentage of maximum frequency
indicated by this field as applied to the CoreFrequency field of the _PSS entry
corresponding to the P-state for which the processor is currently resident.
Power
Latency
Control
Status
Integer
(DWORD)
Integer
(DWORD)
Integer
(DWORD)
Integer
(DWORD)
Indicates the throttling state’s maximum power dissipation (in milliWatts). OSPM
ignores this field on platforms the support P-states, which provide power
dissipation information via the _PSS object.
Indicates the worst-case latency in microseconds that the CPU is unavailable
during a transition from any throttling state to this throttling state.
Indicates the value to be written to the Processor Control Register
(THROTTLE_CTRL) in order to initiate a transition to this throttling state.
Indicates the value that OSPM will compare to a value read from the Throttle
Status Register (THROTTLE_STATUS) to ensure that the transition to the
throttling state was successful. OSPM may always place the CPU in the lowest
power throttling state, but additional states are only available when indicated by
the _TPC control method. A value of zero indicates the transition to the
Throttling state is asynchronous, and as such no status value comparison is
required.
8.4.5.3 _TPC (Throttling Present Capabilities)
This optional object is a method that dynamically indicates to OSPM the number of throttling states
currently supported by the platform. This method returns a number that indicates the _TSS entry
number of the highest power throttling state that OSPM can use at a given time. OSPM may choose
464 April, 2015 Version 6.0