What is Modern Standby?
Windows 10 Modern Standby (Modern Standby) expands the Windows 8.1 Connected Standby power model. Connected Standby, and consequently Modern Standby, enable an instant on / instant off user experience, similar to smartphone power models. Just like the phone, the S0 low power idle model enables the system to stay up-to-date whenever a suitable network is available.
Although Modern Standby enables an instant on/off user experience like Connected Standby, Modern Standby is more inclusive than the Windows 8.1 Connected Standby power model. Modern Standby allows for market segments previously limited to the S3 power model to take advantage of the low power idle model. Example systems include systems based on rotational media and hybrid media (for example, SSD + HDD or SSHD) and/or a NIC that doesn’t support all of the prior requirements for Connected Standby.
The number of systems capable of S0 low power idle model is increasing and we expect more systems to use the always on, instantly available power model instead of the traditional S3/S4 power model. In the Modern Standby section, we have outlined important changes, partner requirements, and best practices for enabling Modern Standby.
Modern Standby is available for both Windows 10 desktop and Windows 10 Mobile.
You cannot switch between S3 and Modern Standby by changing a setting in the BIOS. Switching the power model is not supported in Windows without a complete OS re-install.
Platform is a set of firmware, hardware and software components that delivers an S0 low-power state. The low-power idle state is accomplished through tight integration between the firmware, chipset, low-power components, devices and drivers.
SoC (System on a Chip)
DRIPS (Deepest Runtime Idle Platform State) corresponds to the lowest power state for the SoC during Connected Standby or Modern Standby. Each SoC defines its own DRIPS state and corresponding state index. This is also referred to as S0 low power idle.
Functional Overview of Modern Standby
In Windows 10, the low-power and constant connectivity is achieved by only waking from the lowest power state when absolutely necessary and only allowing software to execute in short, controlled bursts of activity, dramatically reducing the opportunities for software components to execute. Windows and the SoC hardware are always listening for interesting events (such as a network packet or user input at a keyboard) and will wake up instantly when needed. The system will wake when there is real time action required, such as OS maintenance or a user wakes the system.
Modern Standby consists of multiple hardware and software power modes, all of which occur with the screen turned off. The complexity of modern connected standby is a result of keeping the system alive to process background tasks, while ensuring that the system stays quiet enough to achieve long battery life.
Entry to Modern Standby
Modern Standby starts when the user causes the system to enter sleep (e.g user pressing the power button, closing the lid, or selecting Sleep from the power button in the Settings charm). On entry to Modern Standby, apps and system software must be made ready for the transition to low-power operation. (See Prepare software for modern standby.) After software components and apps have been prepared for low-power operation, hardware components, including their software device drivers, must be similarly prepared for low-power operation. (See Prepare hardware for modern standby.) Both software and hardware must be made ready for low-power operation.
Maintenance activity during Modern Standby
During modern standby, Windows transitions the SoC platform from idle mode to active mode a minimum of every 30 seconds to perform kernel maintenance tasks. This maintenance activity is extremely brief in duration (typically no more than a few hundred milliseconds) and cannot be adjusted. In addition, on-demand transitions to active mode can occur in response to user inputs, interrupts from networking devices and other hardware events. Windows transitions the SoC platform from active mode to idle mode after all software activity is stopped and the devices on and off the SoC chip have entered low-power states. (See [Transitioning between active and idle states].)
The networking and communications devices automatically transition between active and low-power modes, based on the software activity of the system during modern connected standby. When there are no system services or Microsoft Store app background tasks that require the network, the networking device is in the low-power, protocol offload, and WoL patterns mode. When a system service or background task requires network access, Windows automatically transitions the networking device to an active mode.
On occasion, the system stays in the active mode (with the screen off) for a longer interval of time. These longer active intervals occur for a variety of reasons, for example, processing incoming email or downloading critical Windows updates. Windows components that are allowed to leave the SoC in the active power state are called activators because they are registered with the power manager as capable of blocking the transition back to the idle power mode. The durations of these activities vary widely but are controlled to extend battery life. The durations of the activities can be viewed with the built-in SleepStudy software tool or through Event Tracing for Windows (ETW) - based instrumentation.
Resume from Modern Standby
When the user causes the system to resume from standby, e.g. presses the power button, the display is immediately turned on and networking devices are restored to their normal, active operating modes. The time from the power button press to the turning on of the display is typically less than 500 milliseconds. After the display is turned on and the networking device returns to normal operating mode, desktop applications resume and the system returns to its normal, screen-on active behavior.