conservative cpugovernor only does one increment

[Johan Ehnberg]

Tested in Jaunty on my Phenom II X4 810 (800/1400/1900/2600 MHz).

My use case: I want to run boinc and still save power by keeping the cpu at lowest clock speed while only load is boinc. When I do something like archiving with gzip, I want all the power I can get. To accomplish this, I need the following things:
- conservative governor (ondemand is too jumpy, reacting on the slightest demand on the same core as boinc)
- ignore nice loads enabled (to separate boinc from other processes like gzip)

So far everything was easy, I chose the governor and set the ignore_nice_load flag in /sys. Boinc did not cause the clock speed to change. However, neither did any other programs like gzip:
cat /dev/urandom |gzip > /dev/null

After investigating this, I noticed that changing the freq_step to a higher value from the default 5 would result in more expected behaviour.
echo 25 > freq_step

However, the frequency now would land at 1900 MHz and stay there, when I'd expect it to change up to 2600 MHz after a while). Changing the above value to 30 or more would cause it to immediately change to 2600 MHz. It changes back to 800 MHz when gzip quits.

For me this variant is acceptable, I expect to always want either powersave or performance, never the middle steps, while still not wasting idle time. However, as far as I can understand, the test shows that the default increment does nothing which is a problem because the governor only seems to do one increment up or down.

(The same behaviour applies for the inverse scenario. If the CPU was manually set to 2600 MHz and 5 freq_step before choosing conservative, it does not change down.)

Linux shadoweel 2.6.28-11-generic #42-Ubuntu SMP Fri Apr 17 01:58:03 UTC 2009 x86_64 GNU/Linux
Ubuntu 2.6.28-11.42-generic

[Andy Whitcroft (apw)]

This is not a bug in the linux-meta package, moving to the linux package.

[Jeremy Foshee (jeremyfoshee)]

Hi Johan,

This bug was reported a while ago and there hasn't been any activity in it recently. We were wondering if this is still an issue? Can you try with the latest development release of Ubuntu? ISO CD images are available from http://cdimage.ubuntu.com/releases/ .

If it remains an issue, could you run the following command from a Terminal (Applications->Accessories->Terminal). It will automatically gather and attach updated debug information to this report.

apport-collect -p linux 364554

Also, if you could test the latest upstream kernel available that would be great. It will allow additional upstream developers to examine the issue. Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Once you've tested the upstream kernel, please remove the 'needs-upstream-testing' tag. This can be done by clicking on the yellow pencil icon next to the tag located at the bottom of the bug description and deleting the 'needs-upstream-testing' text. Please let us know your results.

Thanks in advance.

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[Jeremy Foshee (jeremyfoshee)]

This bug report was marked as Incomplete and has not had any updated comments for quite some time. As a result this bug is being closed. Please reopen if this is still an issue in the current Ubuntu release http://www.ubuntu.com/getubuntu/download . Also, please be sure to provide any requested information that may have been missing. To reopen the bug, click on the current status under the Status column and change the status back to "New". Thanks.

[This is an automated message. Apologies if it has reached you inappropriately; please just reply to this message indicating so.]