ondemand vs conservative

[Daniel Hollocher]

Yeah, I saw that.  I think that is also on wikipedia.  So maybe
ondemand is for battery usage.  It would still be nice to have
conservative for plugged in situations, like a desktop.

I did try to google first, I just didn't see a clear answer.

Dan

On Wed, Sep 29, 2010 at 4:54 PM, Siegfried-Angel Gevatter Pujals
<siegfried at gevatter.com> wrote:
> Hey,
>
> Google gives me this:
> http://www.thinkwiki.org/wiki/How_to_make_use_of_Dynamic_Frequency_Scaling
>
> "The ondemand (available since 2.6.10) and conservative (since 2.6.12)
> are governors based on in kernel implementations of CPU scaling
> algorithms: they scale the CPU frequencies according to the needs
> (like does the userspace frequency scaling daemons, but in kernel).
> They differs in the way they scale up and down. The ondemand governor
> switches to the highest frequency immediately when there is load,
> while the conservative governor increases frequency step by step.
> Likewise they behave the other way round for stepping down frequency
> when the CPU is idle. The conservative governor is good for battery
> powered environments on AMD64 (but may not work on older ThinkPads
> like the T21). Ondemand may not work on older laptops without Enhanced
> SpeedStep due to latency reasons. Anyway, for recent enough Intel CPU,
> ondemand is the one recommended for power efficiency (over userspace,
> and even over "powersave") by the Intel's kernel developer Arjan van
> de Ven"
>
> --
> Siegfried-Angel Gevatter Pujals (RainCT)
> Free Software Developer       363DEAE3
>



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