pm-utils-powersave-policy scripts

Amit Kucheria amit.kucheria at canonical.com
Mon Mar 15 18:36:31 UTC 2010


On 10 Mar 15, Chase Douglas wrote:
> On Mon, Mar 15, 2010 at 5:27 AM, Amit Kucheria
> <amit.kucheria at canonical.com> wrote:
> > Hi Chase,
> >
> > These are the powersave-policy scripts that I've already implemented. Once you
> > make the fixes, it might be a good idea to publish them to a PPA and put out
> > a CFT on ubuntu-devel.
> >
> > These need some fixing as follows:
> >
> > * ac97-powerdown: remove the echo into /dev/dsp, very hackish
> > * console-blanking: redirecting the setterm command to /dev/tty1 ought to
> > configure the timeout
> > * console-blanking-1: just a comment, include with previous script
> > * ethernet-wol: add ethtool dependency in the debian package
> > * sched-multicore:
> > * sched-multithread: fix the script to compare floating point loadavg values,
> > -lt cant do that.
> >
> > For the two sched tweaks, I have the following comments:
> >
> > "Add policy to tune the scheduler to first fill up all threads on a core and
> > all the core in a cpu package before scheduling processes to cores on another
> > cpu package.
> >
> > This kernel tuneable is effective in reducing power consumption on lightly
> > loaded systems.
> >
> > However, this is not a very effective policy since it only takes into account
> > the 15-min load average of the system at the time when pm-powersave is
> > called.  So if the load average changes right after this script is run, we
> > might be making the wrong decision.
> >
> > What we really need is the ability to adjust this tuning constantly, by
> > repeatedly calling this script. Basically a power-policy daemon that is run
> > everytime the processor wakes up for an interrupt. In the long run, this
> > tuning variable might disappear if the scheduler can make this decision
> > automatically."
> 
> I've fixed up all the issues you discussed above except the last part
> about checking the load every so often. The changes can be found at:
> 
> https://code.launchpad.net/~chasedouglas/lucid/pm-utils-powersave-policy

Thanks, will take a look.

> I'll work on a ppa and a CFT soon.
> 
> As for the checking load part, how do we want to deal with it? Any
> script that would check something periodically would need to be
> outside the scope of pm-utils-powersave-policy. We could make a very
> hackish script to go in there, but it's just asking for trouble IMHO.
> So what do we want to do with it? Create a new daemon just for power
> scheduling policy?
> 

I expect sched-mc/mt to eventually become default in kernel whereby the
scheduler will do power-aware scheduling. So let's not try to solve the
problem just yet.

/Amit

-- 
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Amit Kucheria, Kernel Engineer || amit.kucheria at canonical.com
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