Bugzilla – Bug 128616
powersaved should load cpufreq_conservative module
Last modified: 2007-06-05 10:01:40 UTC
I found that powersaved initscript does not load conservative governor that is preferred over ondemand for laptops. Please update /etc/init.d/powersaved, function load_governors(), just below ondemand loader: case "$govs" in *conservative*) ;; *) modprobe -q cpufreq_conservative >/dev/null 2>&1 [ $? != 0 ] && $LOGGER conservative cpufreq governor could not be loaded ;; esac TIA
Hmm, I am not happy about the kernel governors at the moment. There are enough bug reports and not running machines with the ondemand governor, specially SMP and PIII-M machines had a lot of problems in the past with kernel governors. To support and set configs for the conservative governor there is more work needed. Use the userspace governor, it runs more stable and should save the same amount of battery than conservative governor (show figures if not). Seife might also want to comment on this one.
On longterm we might want to support it... will reopen as enhancement.
Seife, will we add this governor? I think it's not worth it? Could you please go on with this bug or just close if you think we don't need this governor or better: If you think supporting it is not a good idea...
For what reasons is this governor especially helpful? It should be easy to add a configuration variable and if set, the conservative governor is used instead of the ondemand governor. But I do not exactly know what are the advantages towards the ondemand governor, though.
we could add it, but i think it is not as simple as just changing the init script. Alexander, have you actually tried it? IIRC (i am not fluent with the latest code) we write the governor to use into the sysfs file from the daemon to be able to switch from kernelspace to userspace, so the daemon needs at least to know about which kernel governor to use. I will look at it, but this is rather low priority right now, since the userspace implementation is well proven, feature rich and works on a larger variety of hardware than the kernel governors and does basically behave like cpufreq_conservative is designed to. I'd take a patch for powersaved of course ;-)
Holger: the conservative governor is a "slow ondemand" governor, which is primary keeping the frequency as low as possible and not tuned for fastest system performance (whcih the ondemand governor is).
Yes I know this, but it also stais longer at an high frequency until it switches back to a low one. Therefor I'm not sure whether it really saves much more power then the userspace governor or even ondemand governor.
Yes, Stephan, I used it a while on my prev. laptop - Toshiba Satellite Pro M30. Frankly, I hadn't noticed much obvious difference between ondemand and conservative, but since kernel people wrote it I think it's worth support it. Holger, if it stays longer in upper freq range than maybe it's time to open bug at kernel.org regarding this? In my opinion, both conservative and ondemand are useful for laptops, the difference is conservative is good for running on battery while ondemand - for running on mains...
Ok, I will do some more testing on that and if it is worth to use the conservative governor when being on battery, we should support it IMO. But as Stefan already mentioned, this is only some kind of enhancement and will go in as time permits.
Ok, this bug is inactive for quite some time. Please decide if there's some work left to do or if it can be closed.
Holger, was your research successful?
Ok, we now load cpufreq_conservative. It is, however, up to the applications that use the hal-cpufreq-addon to use it.