Unable to scale the CPU to minimum available frequency in Red Hat Enterprise Linux 6.3

Solution Verified - Updated -

Environment

  • Red Hat Enterprise Linux 6.3
  • kernel-2.6.32-279.el6
  • Intel(R) Core(TM) i5-2400 CPU @ 3.10GHz

Issue

  • Red Hat Enterprise Linux 6.3 is not able to scale the CPU to minimum available frequency. Is there any known limitation related to this?

Resolution

This is escalated to Engineering team through Red Hat Bugzilla #847934 (not public). Affected hardware which is certified on RHEL6.3 has got exception for CPU scaling test due to this known limitation.

Root Cause

Kernel shipped with Red Hat Enterprise Linux 6.3 is not able to scale certain Intel processors to minimum available frequency. This is known limitation caused due to the fix introduced in RHEL6.3 for Red Hat Bug #752163 (not public)
As a result of this fix, certain CPU never drops below 2.4GHz scaling frequency.

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