See also Power Management

See also other XenServer pages in this wiki

https://wiki.xenserver.org/index.php?title=Power_Management

http://www.ingmarverheij.com/damn-you-c-states-unexpected-xenserver-reboot/

http://support.citrix.com/article/CTX127395

With newer XenServer versions, it is no longer recommended to disable power management in the server BIOS.

Disable all power management in the BIOS:

• AMD Power Now
• Cool'n'Quiet
• Intel SpeedStep
• Enhanced Intel SpeedStep (EIST)

On the XCP/XenServer host as root:

xenpm get-cpufreq-states

No output indicates the (SpeedStep, PowerNow) power management has already been disabled.

xenpm get-cpuidle-states | grep total | uniq

If C2 or higher is listed and there is time spent in that higher level state, this indicates that higher level C-states are still active. Check BIOS settings to disable the higher C-states.

A result above 2 indicates you need to disable power management in the BIOS.

Disable all C-states, including C1E.

If the server BIOS has power management options that leave power management to the BIOS rather than the operating system such as Dell Active Power Controller or HP Power Regulator, also disable this by setting the power management option to OS Control.

Dell:

• Processor Settings → Processor C-State Control
• Processor Settings → Processor C1E

HP:

• Power Management Options → Advanced Power Mgmt Options → Minimum Processor Idle Power State → No C-States
• Power Management Options → Advanced Power Mgmt Options → Minimum Processor Idle Power Package State → No Package State

Intel:

• Advanced → CPU Configuration → Enhanced Intel SpeedStep Technology
• Advanced → CPU Configuration → Turbo Mode (Turbo Boost)
• Advanced → CPU Configuration → CPU C1E
• Advanced → CPU Configuration → CPU C3 Report
• Advanced → CPU Configuration → CPU C6 Report