RSS network throughput performance decreases on Windows Server 2008 R2-based computers that have more than 32 processors

Consider the following scenario:

• A computer is running Windows Server 2008 R2.
• The computer has more than 32 processors in Group 0.
• The computer has one or more 10-gigabit Ethernet (10 GbE) network adapter cards.

When you use receive-side scaling (RSS), the computer experiences decreased network performance, and processor 0 shows 100 percent usage.

This issue occurs when a Network Driver Interface Specification (NDIS) miniport driver uses uninitialized data to select an RSS processor. When this occurs, the NDIS miniport driver selects and uses only processer 0.

Hotfix information

A 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 Web site: Note 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.

Prerequisites

There are no prerequisites for installing this hotfix package.

Registry information

To use one of the hotfixes in this package, you do not have to make any changes to the registry.

Restart requirement

You do have to restart the computer after you apply this hotfix package.

Hotfix replacement information

This hotfix does not replace a previously released hotfix package.

File information

The English (United States) version of this hotfix package uses a Microsoft Windows Installer package to install the hotfix package. The dates and the times for these files are listed in Coordinated Universal Time (UTC) in the following table. When you view the file information, the date is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

Windows Server 2008 R2 file information

The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed separately. MUM and MANIFEST files, and the associated security catalog (.cat) files, are critical to maintaining the state of the updated component. The security catalog files (attributes not listed) are signed with a Microsoft digital signature.

For all supported x64-based versions of Windows Server 2008 R2

For all supported Itanium-based versions of Windows Server 2008 R2

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section of this article.

For more information, click the following article number to view the article in the Microsoft Knowledge Base: