Microsoft KB Archive/824148

= Processor Throttling Does Not Work During a Thermal Event on a Computer That Uses the Mobile Intel Pentium 4 Processor - M with Hyper-Threading Technology =

Article ID: 824148

Article Last Modified on 10/26/2006

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APPLIES TO


 * Microsoft Windows XP Professional
 * Microsoft Windows XP Home Edition

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SYMPTOMS
When Microsoft Windows XP runs on a computer that uses the Mobile Intel Pentium 4 Processor - M with Hyper-Threading Technology (HTT), the Windows processor power management features that control processor throttling during a thermal event (high-temperature condition) may not work correctly. This issue may occur when the adaptive processor dynamic throttling policy is used, such as in the Windows Portable/Laptop power scheme.

During a thermal event, and when CPU utilization is high, the operating system tries to throttle one logical processor by transitioning to a lower processor performance state (P-state) to reduce the thermal demand, while the other logical processor tries to transition to a higher P-state in response to the high CPU utilization. Because of the dependencies between logical processors, the processor package cannot transition to the lower performance state to help reduce thermal demand.



CAUSE
This issue occurs in the Windows kernel power policy manager when Windows XP runs on the HTT-enabled system that is described in the &quot;Symptoms&quot; section.



Service pack information
To resolve this problem, obtain the latest service pack for Microsoft Windows XP. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

322389 How to obtain the latest Windows XP service pack

Hotfix information
A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, Microsoft recommends that you wait for the next Windows XP service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question. The English version of this hotfix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.   Date         Time   Version         Size       File name ---  29-Aug-2003  01:53  5.1.2600.1266   1,896,960  Ntkrnlmp.exe 29-Aug-2003 01:53  5.1.2600.1266   1,953,024  Ntkrnlpa.exe 29-Aug-2003 01:53  5.1.2600.1266   1,924,608  Ntkrpamp.exe 29-Aug-2003 16:57  5.1.2600.1266   2,049,408  Ntoskrnl.exe



STATUS
Microsoft has confirmed that this is a bug in the Microsoft products that are listed in the &quot;Applies to&quot; section of this article. This problem was first corrected in Microsoft Windows XP Service Pack 2.



MORE INFORMATION
The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, regarding the performance or reliability of these products.

