Red Hat Bugzilla – Bug 624499
cpufreq_ondemand does not work on atom
Last modified: 2013-01-10 02:28:27 EST
Description of problem: cpufreq cannot be switched to 'ondemand' but stay on 'performance' at atom machine. Version-Release number of selected component (if applicable): cpufrequtils-007-4.el6.i686 How reproducible: everytime Steps to Reproduce: 1. modprobe p4-clockmod 2. modprobe cpufreq_ondemand 3. echo ondemand > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor Actual results: # cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor performance Expected results: # cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor ondemand Additional info: this patch may help us. http://www.mail-archive.com/linux-kernel@vger.kernel.org/msg191379.html
This issue has been proposed when we are only considering blocker issues in the current Red Hat Enterprise Linux release. ** If you would still like this issue considered for the current release, ask your support representative to file as a blocker on your behalf. Otherwise ask that it be considered for the next Red Hat Enterprise Linux release. **
Thank you for your bug report. This issue was evaluated for inclusion in the current release of Red Hat Enterprise Linux. Unfortunately, we are unable to address this request in the current release. Because we are in the final stage of Red Hat Enterprise Linux 6 development, only significant, release-blocking issues involving serious regressions and data corruption can be considered. If you believe this issue meets the release blocking criteria as defined and communicated to you by your Red Hat Support representative, please ask your representative to file this issue as a blocker for the current release. Otherwise, ask that it be evaluated for inclusion in the next minor release of Red Hat Enterprise Linux.
Thank you for your response. I am not sure if the RHEL6 would take atom-box into consideration as its target. In case of 'Yes', the energy efficiency is quite important for atom-box as eco-linux-box, so that cpufreq must work on the box, I believe. On the other hand, I am afraid the patch I pointed will work fine or not. I'm not technician and not able to evaluate the patch correctly.
p4-clockmod is provided for thermal management purposes only, as it does not support voltage scaling. It will not reduce the energy required to perform a given quantity of work and as such provides no benefit with the ondemand governor. ondemand is only supported on Atom CPUs that provide the Intel Enhanced Speedstep feature.