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HyperThreading and AppLogic

Per the 2.X documentation, Intel hyperthreading was automatically disabled by AppLogic and was not used. This is no longer the case as the new HT model does not allow us to disable it automatically any more as described in the 2.X docs. In the new model it MUST be disabled in the BIOS as we can no longer control it from the kernel programmatically. Therefore, many of our customers currently have it enabled and are not aware. http://doc.3tera.com/AppLogic30/Hardware_Config/index.htm?toc.htm?GridNodesRequirements.html

• HyperThreading (HT) is automatically enabled on servers from the factory which causes many clients to not even notice that it's been enabled even though they may have seen our notice that HyperThreading has not been tested nor is supported by AppLogic. While we are not aware of any current issues with recent releases related to HT and it being enabled on our client grids, we have not had the opportunity to properly test it on the different hardware versions out there so for business liability reasons we currently DO NOT support it and are requesting our customers who have it enabled to disable it.

With HT enabled within AppLogic it causes CPU allocation numbers to report twice as many CPU's as the actual amount. This also affects the configuration of the appliances and the reporting of CPU bandwidth being used via metering.

• This may be another reason why AppLogic users have HT enabled - so that it appears they have more CPU resources available and may be relaying that usage information to their service subscribers.
• A few of our clients have tested HT and are very pleased with the results so they may not want to disable it.
• Other AppLogic users who have HT enabled may not want to disable it because all the Appliances within the grid will need to be adjusted to reflect the difference along with educating their customer of this.

Disable HT through the BIOS during server boot up.

1. Power on the server.
2. Depress the designated key(s) command to be able to edit the BIOS.
3. Select the Hyper Threading Technology (or in some cases Intel HT Technology) option and set it to "DISABLED"
4. Save and Exit the BIOS configuration menu.