Eliot's Blog : Vista

Power Management in Windows Vista

Eliot — Fri, 22 Feb 2008 01:29:00 GMT

Stephen, a program manager on the Windows Kernal team, posted a response to a question in the General Windows Vista Development Issues forum, and I thought it could bear repeating here. The original question was about how to control the processor throttle in Windows Vista. Apparently, some of the calls that used to work in an application geared to Windows XP were not acting the same way in Windows Vista. Here's Stephen's response:

Windows Vista and Windows Server 2008 use a new power policy infrastructure and API. This page details all the power APIs and indicates what is supported by the various Windows versions:

http://msdn2.microsoft.com/en-us/library/aa373163(VS.85).aspx

While some of the older APIs are supported in Vista, it is recommended that you use the new APIs on Windows Vista and later versions.

To give some background, in Windows Vista a power plan (sometimes called a power scheme) contains the power setting values that are actually in effect on the system. A power plan is uniquely identified by a GUID and contains an AC and DC values for each power setting. There can only be one power plan active at a time on the system. The current plan can be obtained using the PowerGetActiveScheme.

Like power plans, power settings are also identified by unique GUIDs and include a friendly name, description, allowable values, and default values for AC and DC. Power setting values can be modified using the PowerWriteACValueIndex and PowerWriteDCValueIndex routines. Note that you must call PowerSetActiveScheme after modifying any of the power settings in order to activate the new values.

Specifically to your question, there are two settings that allow you to adjust the minimum and maximum state for processor power management. These are expressed as a percentage of the maximum processor frequency. Here is a summary of these two settings:

Description	Minimum processor performance state. The performance state is specified as a percentage of maximum processor frequency.
GUID	893dee8e-2bef-41e0-89c6-b55d0929964c
PowerCfg Alias	PROCTHROTTLEMIN
Minimum Value	0
Maximum Value	100
Label	Percentage (%)
Hidden	No

Description	Maximum processor performance state. The performance state is specified as a percentage of maximum processor frequency.
GUID	bc5038f7-23e0-4960-96da-33abaf5935ec
PowerCfg Alias	PROCTHROTTLEMAX
Minimum Value	0
Maximum Value	100
Label	Percentage (%)
Hidden	No

Additional information on Vista power policy is described in detail in the following whitepaper:

http://www.microsoft.com/whdc/system/pnppwr/powermgmt/PMpolicy_Vista.mspx

Cheers,

Stephen [Microsoft]

TechEd is Around the Corner

Eliot — Wed, 20 Feb 2008 21:37:00 GMT

Seriousy, is it June already? Is it time to plant the tomatoes? Are the kids getting ready for summer break? Of course not, but it is now the time to register for TechEd. Do it today and save yourself $200 (US) with an early bird discount.

Speaking of birds (I so rarely get to use a good segue), this is the PERFECT time to submit a proposal for a birds-of-a-feather session. Want to talk with other Tablet PC developers about ink on the Web? Need dire information about app compatibility? Got an itch to drive Silverlight extensions? Go ahead, suggest a session; moderate it. What the heck, you're almost certain to make new contacts and discover important information. Overall, TechEd is about the combination of technology and community. What better way to get value from attending than to drive the discussion?

Here's the skinny straight from the TechEd 2008 homepage for developers:

Tech·Ed U.S. 2008 Developers is Microsoft’s premier technical education conference just for developers. For four days, you and over 5,000 of your peers have endless opportunities to learn about Microsoft’s latest cutting-edge technologies. What better way to start your experience than with a keynote from Bill Gates.

Be a part of the experience
* Design a personalized schedule from 16 Technical Tracks
* Advance your development skills in one of over 340 Breakout Sessions
* Go deep with Microsoft experts in one of more than 220 Interactive Theaters
* Take your time and drill down on a specific task in over 145 Hands-on Labs
* Be a part of this year’s first U.S. Tech·Ed for Developers, June 3-6, 2008 in the Orange County Convention Center, North/South Building, Orlando, Florida.

And if you go, please stop by the Windows Vista booth and say hello. I'm part of the community, too.

Windows Vista Developer Center Updates

Eliot — Fri, 15 Feb 2008 04:08:00 GMT

I just want to get more details in about how the Windows Vista Developer Center has a fresh look and lots of new content. Since becoming the content manager for the site in December, I've been working with members of the Windows Partners Program team, Windows Product Planning, Developer Platform Evangelism, and MSDN to determine how best to get content--real, useful content--up on the developer center. Our first phase of implimentation went live last week, and I can't believe I haven't blogged about the details until today.

Some of the things we added:

A full page explaining the value proposition of Why Develop for Windows Vista
Functionally sorted features of What's New in Windows Vista, with links to reference materials for each feature set
An updated list of downloads and samples
Over 60 "How-do-I" videos showing how to code with managed and native APIs
Relevant links from Code Gallery projects
Webcasts, virtual labs, blog aggregates, and much, much more

But I know that I missed something. Probably a lot of somethings. Please leave a comment and tell me what you think of the redesign and also what you like to see added or changed.

Thanks, and Happy Valentine's Day

Developer Security Enhancements in Windows Vista SP1

Eliot — Tue, 12 Feb 2008 23:33:00 GMT

This comes via Michael Howard's Web Log. Take a look at the full post, but here are some salient bits.

New NX APIs added to Windows Vista SP1, Windows XP SP3 and Windows Server 2008

In the interests of helping secure the platform, we want more people to opt-in to using Data Execution Prevention (aka DEP aka NX), and we have lowered the barrier to entry for application developers in Windows Vista SP1, Windows XP SP3 and Windows Server 2008.

We've added some new APIs that allow a developer to set DEP on their process at runtime rather than using linker options. The new APIs also give developers some more flexibility if your application uses an older version of the Active Template Library (ATL.)

...

The most important API added is SetProcessDEPPolicy, which sets the DEP policy for the running process. You would normally use this function pretty early in main.

The function takes only one argument: the policy setting. The possible values are:

0x00000000 Turn off DEP for this process (Why are you doing this?)
PROCESS_DEP_ENABLE Enable DEP for the process.
PROCESS_DEP_ENABLE | PROCESS_DEP_DISABLE_ATL_THUNK_EMULATION Enable DEP for the process, and disallow ATL thunks.

The last option is the killer argument - if you build an application that hosts components that might not be DEP compatible because they were built using an older version of ATL, you can still use DEP for your process.

Windows Vista Developer Center Updated

Eliot — Thu, 07 Feb 2008 02:53:00 GMT

The Windows Vista Developer Center on MSDN has been scrubbed, polished, reorganized, blown dry, and is now free to peruse. The developer center now includes easier navigation, links to over fifty "How Do I" videos, RSS feeds for the Windows Shell team's blog, Shell:revealed, and a ton of content about why you should develop applications directly for Windows Vista. Just take a look at the What's New in Windows Vista page, and use that as your springboard to identify useful new technologies and to find relavent materials throughout MSDN and TechNet.

Seriously, the reorganization is a ton of help in getting into where you need to be.