3 Ways That Windows is Smarter With Power

Typically laptop users are the ones who care most about power consumption, as it directly affects battery life, but it's also a full-on concern for those who are looking at their energy bills – and this includes massive corporations where pennies can multiply into thousands of dollars.

Windows 8 will have a host of new features that make the user experience more productive and enjoyable, but under the hood will be further efforts in efficient and effective power management.

Pat Stemen, a program manager on the Windows Kernel team, detailed on the B8 Blog three innovations in Windows 8 that influence power consumption: the Metro style app model, idle hygiene, and a new runtime device power management framework.

On the Metro style app model:

The Metro style application model is designed from the beginning to be power-friendly. The power management benefit is that the model makes it easy for developers to ensure their application is running only at the right time—applications in the background are suspended such that they do not consume resources and power when not in use.Of course, we recognize that background activity is a critical component of apps that are always connected and responsive. The Metro style application model and the underlying WinRT support background activity through a new set of capabilities called background tasks. … Background tasks make it easy to perform background activity in a power-friendly fashion. They also enable developers to continue to deliver responsiveness and “freshness” in their applications, but the mechanisms are different than the existing Win32 model because of the desire for a fast-and-fluid interface and the other key attributes of Metro style apps….

On idle hygiene:

Most PC platforms feature processor and chipset idle states that allow the hardware platform to stop the clock or completely turn off power to parts of the silicon when they are unused. These idle states are absolutely critical to enabling long battery life, but they require a minimal residency duration—that is, you have to be idle for long enough to make the transition in and out of the idle state worthwhile in terms of power used. This is because some power is consumed on the way into and out of the idle state. Software most effectively uses these idle states when there are as few exits from the idle state as possible, and the duration of the idle state is as long as possible.We track the idle efficiency of Windows 8 using built-in ETW Tracing, some additions to the Windows Performance Analyzer, and a basic histogram. Below, you can see the difference in idle durations between Windows 7 and Windows 8. When the screen is on, we’ve already moved the bar significantly from a maximum idle duration of 15.6ms in Windows 7 to 35% of our durations longer than 100ms in Windows 8! With the screen off and during Connected Standby, our idle durations are even longer, currently in the tens of seconds.

On runtime device power management:

For Windows 8, we’ve built a new device power framework that allows all devices to advertise their power management capabilities and integrate them with a special driver called the Power Engine Plug-in or PEP, designed for SoC systems. The PEP is provided by the silicon manufacturer and knows all of the SoC-specific power management requirements. This allows device drivers like our USB host controller or a keyboard driver to be built once, and still deliver optimal power management on all platforms from SoC-based PCs to datacenter servers.

Marcus Yam
Marcus Yam served as Tom's Hardware News Director during 2008-2014. He entered tech media in the late 90s and fondly remembers the days when an overclocked Celeron 300A and Voodoo2 SLI comprised a gaming rig with the ultimate street cred.
  • "3 Ways That Windows 8 Smarter With Power"

    Windows 8 like power. But fire bad - FIRE BAD!!!
  • Me Tarzan, you Marcus.
  • So, basically, this is one of those "nothing we weren't already doing" features, but completely re-written to ensure that it's completely broken until Windows 8 SP1 drops?
  • back_by_demand
    A cool idea for power management would be a proximity sensor in a laptop that can tell if you are sat with in X amount of feet, hopefully user defined, so if you get up to take a whizz, grab a brewsky from the fridge or answer the door to the pizza dude, the screen turns off automatically, then back on when you return.

    It's not just corporations that worry about the power costs, a high-end user can waste enough electricity in a year to buy a new 2Tb hard drive, the way I see it good power management is another way of saying upgrades afforded sooner.
  • cybersans
    good news to idling system. i use to run my pc almost 24/7 and currently using ws08 r2 and power management is quite well. with this kind of news, for the next windows server (2012 maybe) if this news were right, it will consume less juice too.
  • I think the biggest power user is the Monitor and the type of computer. I think more businesses will begging to rethink bigger monitors unless they can create a better way of reducing consumption. One way I thought of was to have a sensor to monitor if someone is sitting near the monitor. I think someone else hear mention it too. That's a great ideal to put monitor to sleep only when nobody is using it. I think lower powered more precise engineered PC's will be helpful too. Such as not over powered PC's and graphics. I think the OS can only do what the hardware allows.
  • pocketdrummer
    __-_-_-__there's a smarter way. it's called: linux.
    Never speak again. You've lost internet privileges.
  • ___-_-_-__ : I can agree that Linux does many, many things better than Windows, but power management is not one of them on many systems, whereas the systems that run Linux well only tie Windows for power management.

    In all fairness though, it's not their fault, as they had to reverse engineer a lot of the ACPI standards, as well as the ACPI quirks for individual motherboards. There are some famous emails subpoenaed from Bill Gates himself during the 90s in regards to using ACPI as a tool to sabotage and obstruct Linux's hardware support.
  • One way I thought of was to have a sensor to monitor if someone is sitting near the monitor.

    That would be a cool use MS could make of kinect, have kinect turn on the camera when trigged by a sound like voices or a door opening, then have the monitor turn on and Windows boot from standby if the camera sees someone.
  • phyco126
    Monitors consume a negligible amount of energy. Yes, you can get lower your energy consumption a little, but implementing what you guys have suggest may, at best, save someone a dollar a year on their bill. The processor using a ton of energy, followed by RAM, the GPU (the GPU can be first on this list), and then the HDDs. If you really want to save money, get energy efficient RAM, a low end GPU, and a ultra-efficient processor.