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PEP_PROCESSOR_IDLE_STATE_V2 structure (pepfx.h)

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The PEP_PROCESSOR_IDLE_STATE_V2 structure describes a processor idle state that the platform extension plug-in (PEP) supports.

Syntax

typedef struct _PEP_PROCESSOR_IDLE_STATE_V2 {
  union {
    ULONG Ulong;
    struct {
      ULONG Interruptible : 1;
      ULONG CacheCoherent : 1;
      ULONG ThreadContextRetained : 1;
      ULONG CStateType : 4;
      ULONG WakesSpuriously : 1;
      ULONG PlatformOnly : 1;
      ULONG Autonomous : 1;
      ULONG Reserved : 22;
    };
  };
  ULONG Latency;
  ULONG BreakEvenDuration;
} PEP_PROCESSOR_IDLE_STATE_V2, *PPEP_PROCESSOR_IDLE_STATE_V2;

Members

Ulong

Flag bits and status fields accessed as a single 32-bit unsigned integer value.

Interruptible

Whether the processor can respond to interrupts when in this idle state. Set this flag bit to 1 if the processor can respond to interrupts, and to 0 if it cannot.

CacheCoherent

Whether the processor's local cache or caches remain coherent through the duration of this processor idle state. Set this flag bit to 1 if cache coherency is maintained in this idle state, and to 0 if it is not.

ThreadContextRetained

Whether thread context is retained in this processor idle state. Set this flag bit to 1 if the processor hardware retains the thread context across the idle transition. Set to 0 if the processor uses the multiprocessor parking protocol to exit the idle state and return control to the operating system. For more information about this protocol, see the document titled Multiprocessor Startup for ARM Platforms at the ACPI Component Architecture site.

CStateType

The C-state type of the processor idle state. Set this bit field to zero if this idle state does not correspond to an ACPI-defined C-state. Otherwise, set this bit field to the C-state number. That is, set CStateType = 1 for C1, set CStateType = 2 for C2, and so on. For more information about C-states, see section 8.1, "Processor Power States", of the ACPI 5.0 specification.

WakesSpuriously

Whether the processor can wake spuriously in this idle state. Set this flag bit to 0 if the processor is guaranteed to stay in this idle state until it receives a device interrupt, inter-processor interrupt (IPI), or wake request. Set to 1 if the processor might wake autonomously for some other reason.

PlatformOnly

Whether the transition to this processor idle state can be performed only as part of a coordinated transition to a platform-wide idle state. Set this flag bit to 1 if the processor idle state transition can be performed only as part of a transition to a platform idle state. Otherwise, set to 0.

Autonomous

Whether a coordinated transition to this processor idle state is performed autonomously by the processor hardware. Set this flag bit to 1 if these transitions are autonomous, and to 0 if they are not. A flag value of 1 indicates that the idle state can be entered without sending a PEP_NOTIFY_PPM_TEST_IDLE_STATE, PEP_NOTIFY_PPM_IDLE_PRE_EXECUTE, or PEP_NOTIFY_PPM_IDLE_COMPLETE notification. This flag can be set to 1 only if CStateType is nonzero.

Reserved

Reserved for future use. Set to zero.

Latency

The worst-case latency, in 100-nanosecond units, that the processor requires to wake from this idle state in response to a wake event.

BreakEvenDuration

The minimum amount of time, specified in 100-nanosecond units, that the processor must spend in this idle state to make a transition to this state worthwhile. The Windows power management framework (PoFx) uses this member value as a hint to avoid switching a processor to an idle state unless the processor is likely to remain in this state for at least the amount of time specified by BreakEvenDuration.

Remarks

This structure is used in conjunction with the PEP_NOTIFY_PPM_QUERY_IDLE_STATES_V2 notification. The IdleStates member of the PEP_PPM_QUERY_IDLE_STATES_V2 structure is the first element in an array of PEP_PROCESSOR_IDLE_STATE_V2 structures.

The unnamed union contains a collection of flag bits and status fields that can be accessed either individually as bit fields, or together as a 32-bit unsigned integer value.

The unnamed struct contains flag bits and status fields accessed as individual bit fields.

Requirements

Requirement Value
Minimum supported client Supported starting with Windows 10.
Header pepfx.h (include Pep_x.h)

See also