Red Hat Bugzilla – Bug 204047
Frequency scaling fails for powernow-k8 driver with the xen0 kernel
Last modified: 2007-11-30 17:11:41 EST
Description of problem:
CPU frequency scaling does not work. Logs show a bunch of:
Aug 18 06:49:32 localhost kernel: powernow-k8: transition frequency failed
Aug 18 06:49:32 localhost kernel: powernow-k8: fid trans failed, fid 0xc, curr 0
Version-Release number of selected component (if applicable):
Tested up till kernel kernel-xen0-2.6.17-1.2174_FC5.
Steps to Reproduce:
1. Just boot up and observe logs.
Errors as above appear, CPU frequency is always at max.
Should not have above errors. CPU frequency should drop during idle load.
Understand there is a patch to fix the powernow-k8 driver. Refer to this mailing
The patch in question is:
Changing to proper owner, kernel-maint.
A new kernel update has been released (Version: 2.6.18-1.2200.fc5)
based upon a new upstream kernel release.
Please retest against this new kernel, as a large number of patches
go into each upstream release, possibly including changes that
may address this problem.
This bug has been placed in NEEDINFO state.
Due to the large volume of inactive bugs in bugzilla, if this bug is
still in this state in two weeks time, it will be closed.
Should this bug still be relevant after this period, the reporter
can reopen the bug at any time. Any other users on the Cc: list
of this bug can request that the bug be reopened by adding a
comment to the bug.
In the last few updates, some users upgrading from FC4->FC5
have reported that installing a kernel update has left their
systems unbootable. If you have been affected by this problem
please check you only have one version of device-mapper & lvm2
installed. See bug 207474 for further details.
If this bug is a problem preventing you from installing the
release this version is filed against, please see bug 169613.
If this bug has been fixed, but you are now experiencing a different
problem, please file a separate bug for the new problem.
Hi, trying out now with the new 2.6.18-1.2200.fc5xen0 kernel. The powernow-k8
errors are still present and CPU frequency scaling still does not work (always
at max frequency).
In FC6 and rawhide, we have disabled Xen CPU frequency scaling because it simply
will not work right even with simple driver or hypervisor changes.
The reason for this is that dom0 might not be running on every CPU in the
system, and dom0 has no idea how busy the guests are - hence it will end up
doing the wrong thing CPU frequency wise anyway.
Proper CPU frequency scaling for Xen will have to be done in the upstream Xen
project first. After that we can integrate the changes in Fedora.
*** Bug 204196 has been marked as a duplicate of this bug. ***