Re: [gentoo-amd64] complete crash with ondemand scheduler

[Joshua Hoblitt <jhoblitt@ifa.hawaii.edu>]

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Your statement was that the on-demand governor is "very bad" for amd
CPUs.  I don't see how you have qualified that statement in any way.
Yes, it behaves differently then the conservative governor but that
doesn't make it "bad", "harmful", or even inefficient with power usage.

I use the ondemand govern on a large number of production Opteron
machines with great results.  According to my empirical measurements
with an ammeter it saves an average of ~35w per socket in systems with
dual core CPUs (not per core).  As you can imagine, this is a pretty use
full savings for the 8-socket system that I have.

Cheers,

-J

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On Fri, Aug 03, 2007 at 02:50:48PM +0200, Beso wrote:
> the ondemand governor steps the processor between the least step to the most
> one. for example, i have a turion 64 with steps from 800mhz to 2ghz. the
> ondemand governor would step from 800mhz directly to 2ghz when the cpu is
> under load and then return to 800 mhz when the load drops down.
> the conservative governor instead steps to the most intelligent frequency
> when it is needed. on my processor it steps to 1200mhz, or to 1,6ghz or
> 1,8ghz based on the load of the processor, but sometimes it lags a bit
> before going to upper steps. of course you can set it according to the wiki
> and forum information in the best way for your system.
> then there are powernowd and powerthend, which are based on userspace
> governor.
> i'm actually using the first one (which is in the gentoo main repository)
> and i find quite good with it, that steps quite good and in a quite smooth
> way. i'll look for some tweaking for it because there are still some things
> i don't like (mainly when copying to a truecrypted volume).
> the last one is another daemon which is outside the gentoo repository, so
> you'll have to go to their site ( http://powerthend.scheissname.de/ ) and
> add the overlay to portage or you can download the source and compile it
> manualy. i reccomend adding the overlay so that you can have it in the world
> db. this one is quite a good daemon but for my standards it jumps too much
> the processor current speed but it is really good cause i don't even know of
> processor lags when transitioning from one step to another if i don't take a
> look at kima (a little kmenu applet that let you see thermal temp, core
> temp, cpufreq speed, uptime, and proc speed, that normally is equal to the
> cpufreqspeed). if you'd like to try it, try it first and if you think that
> is steps too much turn to powernowd.
> the only thing that you need to know is that this 2 daemons need the
> userspace governor built in the kernel or loaded and set when they start.
> for that reason i use cpufrequtils to set the governor to userspace and
> powernowd/powerthend to actually set the cpu speed of my processor.
> i've read that you had a new processor with cool&quiet so i think that you
> should really use this tools to get the powernowd! technology working. maybe
> on the wiki you could find something also about cool&quiet and on how to
> tune it.
> the last thing i would advise to use is the klaptopdaemon. it is a fantastic
> kde daemon that is capable of controlling cpu steps, standby, suspend which
> are quite great, at least for my laptop. i don't know if it works also on a
> desktop, but if not there is kpowersaved which is quite good also.
> 
> 2007/8/3, Raffaele BELARDI <raffaele.belardi@st.com>:
> >
> > Beso,
> >
> > that is an interesting observation, can you elaborate a bit?
> >
> > thanks,
> >
> > raffaele
> >
> > Beso wrote:
> > >
> > > and for amd users, i suggest not using the ondemand governor cause it
> > > uses the cpu in a very bad way. use conservative one or userspace with
> > > powernowd or powerthend (the last one on my systems gave a better
> > > efficiency).
> > >
> >
> > --
> > gentoo-amd64@gentoo.org mailing list
> >
> >
> 
> 
> -- 
> dott. ing. beso

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