On the IBM x3850 x5 and x3690 x5 systems, some CPUs may not throttle with the "userspace" CPU frequency scaling governor in Red Hat Enterprise Linux 6 or Red Hat OpenStack 3.0

Issue

When using the "userspace" CPU frequency scaling governor with the IBM x3850 x5 or x3690 x5 systems, some CPUs in the system may not throttle down to the specified speed. This will result in slightly higher power usage, however it will have no negative performance impact.

Environment

• Red Hat Enterprise Linux 6
• Red Hat OpenStack 3.0

• IBM x3850 x5 or x3690 x5

• "userspace" CPU frequency scaling governor

Resolution

Customers are advised to use the "ondemand" CPU frequency scaling governor, which is the default in Red Hat Enterprise Linux 6 or Red Hat OpenStack 3.0.