RtcplSetWindowsIdleState

The function RtcplSetWindowsIdleState specifies whether to prevent the system from entering a Windows idle state.

Syntax

BOOL RtcplSetWindowsIdleState(
    DWORD Enable
);

Parameters

Enable

Specifies whether to let the system enter a Windows idle state or use Intel Speedstep modifications. In an effort to save energy, Intel Speedstep technology switches your processor speed to a lower setting when the processor has been in an idle state for some period of time. When the machine begins processing tasks again, the CPU returns to the higher speed. Returning from the lower speed to a higher speed, however, can cause latencies to happen and may negatively affect RTSS processes. Therefore, RTX offers the following options to control a machine's idle state.

Value	Description
GENERAL_DISABLE	RTX allows the system to enter a Windows idle state or use Intel Speedstep modifications. This effectively disables power management features.
ENABLE_NO_C1_IDLE	This option uses internal Windows power management logic to prevent the machine from entering a C1 idle state. On certain systems, this setting can cause your CPU to run at reduced speeds.
ENABLE_NO_IDLE	This option prevents the Windows idle thread from running by running an RTSS idle thread instead. Intel Speedstep modifications occur after the Windows idle thread has run for some period of time, so by disabling the Windows idle thread, you effectively disable Intel Speedstep technology as well. As a side effect, this setting causes 100% CPU utilization to appear in the Windows Task Manager, however, you can view accurate CPU utilitization statistics in PerformanceView instead.

ENABLE_NO_C1_IDLE and ENABLE_NO_IDLE may be OR'd together (ENABLE_NO_C1_IDLE | ENABLE_NO_IDLE) if you want both options enabled.

Return Values

A non-zero value, regardless of whether the function succeeds or fails.

Remarks

Changing this value requires a restart of the RTX Subsystem if it is running, as indicated by a GetLastError of ERROR_SUCCESS_RESTART_REQUIRED.

Related RTX Properties Control Panel Features

Tab	Hardware tab
Feature(s)	Prevent Windows idle state and Use Power Management Functionality to Prevent C1 Idle State options

Requirements

Header	RtxProp.h
Library	RtxProp.lib

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