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Hypervisor does not provide timer services correctly on a Windows 2008 R2-based Hyper-V server
Article ID: 2740390 - View products that this article applies to.
On a Windows Server 2008 R2-based Hyper-V server, you experience one of the following issues.
Issue 1Assume that you have a virtual machine that is running on a Windows Server 2008 R2-based Hyper-V server. In this situation, the current calibration code in the time stamp counter (TSC) scaling factor of the hypervisor has insufficient precision in the virtual machine.
Issue 2Assume that you have a virtual machine that is running on a Windows Server 2008 R2-based Hyper-V server. Under certain circumstances, the hypervisor does not deliver one or more timer ticks to the virtual machine.
Cause of Issue 1This issues occurs because a TSC cycle source is translated to a reference time that is inaccurate. The time difference between the virtual machine and the server depends on the processor speed. This behavior is insufficient for an accurate translation from a TSC cycle source to a reference time.
Note Usually, the clock speed of the processor is equal to 10 megahertz (MHz). The time difference is less than 10 milliseconds on most processors.
Cause of Issue 2This issue occurs because the hypervisor does not use a sufficient level of precision for describing the duration of periodic timer ticks.
Hotfix informationA supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing the problem described in this article. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.
If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.
Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft website:
http://support.microsoft.com/contactus/?ws=supportNote The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.
PrerequisitesTo apply this hotfix, you must be running Windows Server 2008 R2 or Windows Server 2008 R2 Service Pack 1 (SP1). Additionally, you must have the Hyper-V role installed on the computer.
For more information about how to obtain a Windows 7 or Windows Server 2008 R2 service pack, click the following article number to view the article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/976932/ )Information about Service Pack 1 for Windows 7 and for Windows Server 2008 R2
Registry informationTo apply this hotfix, you do not have to make any changes to the registry.
Restart requirementYou must restart the computer after you apply this hotfix.
Hotfix replacement informationThis hotfix does not replace a previously released hotfix.
File informationThe global version of this hotfix installs files that have the attributes that are listed in the following tables. The dates and the times for these files are listed in Coordinated Universal Time (UTC). The dates and the times for these files on your local computer are displayed in your local time together with your current daylight saving time (DST) bias. Additionally, the dates and the times may change when you perform certain operations on the files.
Windows Server 2008 R2 file information notesImportant Windows 7 hotfixes and Windows Server 2008 R2 hotfixes are included in the same packages. However, hotfixes on the Hotfix Request page are listed under both operating systems. To request the hotfix package that applies to one or both operating systems, select the hotfix that is listed under "Windows 7/Windows Server 2008 R2" on the page. Always refer to the "Applies To" section in articles to determine the actual operating system that each hotfix applies to.
For all supported x64-based versions of Windows Server 2008 R2
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Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
For more information about the reference TSC page, go to the following Microsoft website:
General information about the reference TSC pageFor more information about the timer services that are provided by hypervisor, go to the following Microsoft website:
General information about the timer services that are provide by hypervisorFor more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/824684/ )Description of the standard terminology that is used to describe Microsoft software updates
Additional file information
Additional file information for Windows Server 2008 R2
Additional files for all supported x64-based versions of Windows Server 2008 R2
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