Microsoft KB Archive/838150

= Intel Physical Address Extensions cause high CPU usage in Windows 2000 =

Article ID: 838150

Article Last Modified on 10/26/2006

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APPLIES TO


 * Microsoft Windows 2000 Advanced Server
 * Microsoft Windows 2000 Datacenter Server

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SYMPTOMS
Consider this scenario: You use Intel Physical Addressing Extensions (PAE) on a computer that is running Microsoft Windows 2000 Advanced Server and that has more than 4 gigabytes of RAM. When the computer is under a heavy input/output (I/O) load, 80 to 100 percent of the CPU resources are used. If you do not use PAE, and the CPU is under a heavy I/O load, only 20 to 30 percent of the CPU resources are used. You expect that performance would be better when you use PAE.



CAUSE
This problem may occur if the Scsiport.sys driver allocates memory as non-cached, instead of cached, when you use PAE.



Hotfix information
A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that this article describes. Apply it only to systems that are experiencing this specific problem.

To resolve this problem, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone 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.

Prerequisites
You must have Windows 2000 SP4 installed to apply this hotfix.

Restart requirement
You must restart your computer after you apply this hotfix.

Hotfix replacement information
This hotfix does not replace any other hotfixes.

File information
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 --  09-Mar-2004  18:54  5.0.2195.6906      74,128  Scsiport.sys



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.



MORE INFORMATION
For additional information about PAE, click the following article numbers to view the articles in the Microsoft Knowledge Base:

268363 Intel Physical Addressing Extensions (PAE) in Windows 2000

283037 Large memory support is available in Windows 2000 and Windows Server 2003

For additional information, click the following article numbers to view the articles in the Microsoft Knowledge Base:

816915 New file naming schema for Microsoft Windows software update packages

824684 Description of the standard terminology that is used to describe Microsoft software updates

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.

Additional query words: /PAE, Boot.ini

Keywords: kbhotfixserver kbqfe kbbug kbfix kbqfe kbwin2000presp5fix KB838150

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