Red Hat Bugzilla – Bug 591448
Performance degradation with AMD PhenomII X6 Turbo-Core feature
Last modified: 2010-06-03 04:06:34 EDT
Description of problem:
AMD's Six-Core processor have a Turbo-Core feature automatically activated without software involvement. Due to a conflict with the powernow-k8 driver this feature is not activated under recent Linux kernel versions, resulting in bad performance.
Version-Release number of selected component (if applicable):
all Linux kernels starting from 2.6.30, including the Fedora13 version
Do performance testing with AMD's desktop Six-Core processors featuring Turbo-Core (PhenomII X6 1090T and 1055T). Compare the performance to that with the Cool'n'Quiet _disabled_ in the BIOS.
Steps to Reproduce:
1. Boot Fedora13 on an AMD PhenomII X6 processor
2. Do some performance testing
3. Disable Cool'n'Quiet feature in the BIOS
4. Repeat performance testing, compare numbers to that of Step2
Performance with C'n'Q enabled is worse than with C'n'Q disabled.
Performance with C'n'Q enabled should be equal or better compared to C'n'Q disabled.
Following online articles describe the problem:
The appropriate fix (a one-liner):
is already in 2.6.34-rc7 and will trickle down into stable soon.
Please cherry-pick this one into the Fedora13 release kernel.