Microsoft KB Archive/895980

= Programs that use the QueryPerformanceCounter function may perform poorly in Windows Server 2003 and in Windows XP =

Article ID: 895980

Article Last Modified on 10/11/2007

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APPLIES TO


 * Microsoft Windows Server 2003, Datacenter x64 Edition
 * Microsoft Windows Server 2003, Enterprise x64 Edition
 * Microsoft Windows Server 2003, Standard x64 Edition
 * Microsoft Windows Server 2003, Datacenter Edition (32-bit x86)
 * Microsoft Windows Server 2003, Enterprise Edition
 * Microsoft Windows Server 2003, Standard Edition (32-bit x86)
 * Microsoft Windows Server 2003, Web Edition
 * Microsoft Windows XP Professional x64 Edition
 * Microsoft Windows XP Professional

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SYMPTOMS
In Microsoft Windows Server 2003 and in Microsoft Windows XP, a program that uses the QueryPerformanceCounter function to query system time may perform poorly. For example, if you run the ping command at the command prompt, you may receive low or incorrect latency values.

Note This problem occurs on computers that are running an x64-based version of Windows or an x86-based (32-bit) version of Windows.



CAUSE
This problem occurs when the computer has the AMD Cool'n'Quiet technology enabled in the BIOS.



RESOLUTION
To resolve this problem, update the BIOS on the computer. Or, modify the Boot.ini file to use the /usepmtimer switch. To do this, follow these steps:  Log on to the computer by using an account that has administrative credentials. Click Start, click Run, type notepad c:\boot.ini, and then click OK. In the Boot.ini file, a line that starts with &quot;default&quot; is located in the &quot;[boot loader]&quot; section. This line specifies the location of the default operating system. The line may appear as follows:

default=multi(0)disk(0)rdisk(0)partition(2)\WINDOWS

In the &quot;[operating systems]&quot; section, locate the line for the operating system that corresponds to the &quot;default&quot; line. For example, if the computer is running Microsoft Windows Server 2003, Enterprise x64 Edition, the line should resemble the following:

multi(0)disk(0)rdisk(0)partition(2)\WINDOWS=&quot;Windows Server 2003 Enterprise x64 Edition&quot; /fastdetect /NoExecute=OptIn

 At the end of the line, add a space, and then type /usepmtimer. The line should now resemble the following.

multi(0)disk(0)rdisk(0)partition(2)\WINDOWS=&quot;Windows Server 2003 Enterprise x64 Edition&quot; /fastdetect /NoExecute=OptIn /usepmtimer

 Save the file, and then exit Notepad. Restart the computer.</ol>

The following is a sample Boot.ini file for a system that contains the /usepmtimer switch.

[boot loader]

timeout=0

default=multi(0)disk(0)rdisk(0)partition(2)\WINDOWS

[operating systems]

multi(0)disk(0)rdisk(0)partition(2)\WINDOWS=&quot;Windows Server 2003 Enterprise x64 Edition&quot; /fastdetect /NoExecute=OptIn /usepmtimer

Note The Boot.ini file is located in the root folder of the system drive.

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Technical support for x64-based versions of Microsoft Windows
If your hardware came with a Microsoft Windows x64 edition already installed, your hardware manufacturer provides technical support and assistance for the Windows x64 edition. In this case, your hardware manufacturer provides support because a Windows x64 edition was included with your hardware. Your hardware manufacturer might have customized the Windows x64 edition installation by using unique components. Unique components might include specific device drivers or might include optional settings to maximize the performance of the hardware. Microsoft will provide reasonable-effort assistance if you need technical help with a Windows x64 edition. However, you might have to contact your manufacturer directly. Your manufacturer is best qualified to support the software that your manufacturer installed on the hardware. If you purchased a Windows x64 edition such as a Microsoft Windows Server 2003 x64 edition separately, contact Microsoft for technical support.

For product information about Microsoft Windows XP Professional x64 Edition, visit the following Microsoft Web site:

http://www.microsoft.com/windowsxp/64bit/default.mspx

For product information about x64-based versions of Microsoft Windows Server 2003, visit the following Microsoft Web site:

http://www.microsoft.com/windowsserver2003/64bit/x64/default.mspx

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: cool n' quiet Winx64 Windowsx64 64bit 64-bit Winx86 Windowsx86 32bit 32-bit

Keywords: kbtshoot kbprb KB895980

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