Sales Are Looking Good--if you're stocking laptops

Eliot — Tue, 11 Mar 2008 01:00:00 GMT

Last week I published an article in the Mobile PC Newsletter (brash and brazen plug, go subscribe through https://profile.microsoft.com/. You just need a Windows Live Passport.) that Mobile PC Growth in India Is Almost 20 Percent in 2007. And then today I saw an article in Ireland's Silicon Republic that talks about how Notebook momentum is driving European PC growth. To quote:

European demand for notebook computers showed no signs of abating in the past year and resulted in over 88 million devices shipped in the region but going into 2008, connectivity alliances between PC vendors and telcos will transform the shape of the market.

The Europe, Middle East and Africa (EMEA) PC market recorded an outstanding year in 2007, according to IDC’s latest tracker, as PC shipments increased 15.9% year-on-year.

Those are some mind-boggling numbers. There are a lot of machines out there that need good software to perform well. A LOT.

The other thing I think is interesting is that this means that we're definitely shifting to where more and more people are using mobile PCs--notebooks, Tablet PCs, UMPCs, desktop replacements--and the applications that run on them. We're talking about a computer that's only sometimes plugged in, encounters multiple networks through a session, relies on power management to make it through the day, and is asked to work well indoors, outdoors, in coffee shops, on my desk, and in someone else's home. There are the obvious hardware needs--take for instance that it must weigh less that 8 pounds (I hear you laughing)--but there are also many software considerations.

I worked on the team that spent two years documenting the considerations for Mobile PC Developers. You can find them all in the User Experience Guidelines for Developers in MSDN. I think we did a good job laying out the various categories unique to notebook development. I know the APIs are not that difficult, because I understand them. And yet I see precious few applications availing themselves of power management, network location, and Tablet and Touch technologies.

I wonder why. Seems to me that anyone whose app absolutely shone on notebooks, Tablet PCs, UMPCs, and other portable computers would stand to make a huge splash, earning enough money that, as former governor Haley Barbour said yesterday, "they could burn a wet mule."

Well, you know what I mean.

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]

Eliot's Blog : power management

Sales Are Looking Good--if you're stocking laptops

Power Management in Windows Vista