[vdr] Re: Shutdown frontend for saving power and heat

["Christian Vogt" <c.v@nexgo.de>]

Hi Reinhard,


----- Original Message -----
From: "Reinhard Walter Buchner" <rw.buchner@freenet.de>
>
> If you measure on the mains side,
> *any* fluctuation (HDD starting up, shutting down, CRON job,
>  background scan etc, i.e just about anything doing something
> with the HDD, graphics card, modem, LAN, ==> simply *the*
> computer hardware) will mess up the measurement.

Yes, I know what you mean and it is completely correct. But the measurement
isn't messed up, because I wanted to measure exactly this: the power
dissipation of the whole computer during different (more or less stable)
modes of operation.

( Maybe I should mention that I have a dedicated system for VDR. If a system
is used for a large amount of other tasks like router, file and/or print
server, seti@home-client or whatever at the same time, such a measurement is
really useless. )

> So e.g saying:
>
> > - additionally VDR started, watching TV using transfer
> >   mode: 57..59W
> > - doing the timeshift-thing: 59..60W
>
> says nothing if the DVB card *really* consumed more power
> during it's stay in the timing-shifting mode.

Again, you're completely right!
But I'm not interested in the DVB card only. I want to see the complete
system. The values above shows that on my system (and this is only valid for
my system, e.g. hardware, software and setup), watching TV in transfer mode
and in timeshift mode consumes both nearly the same amount of power, the
latter maybe slightly more.


> You could smooth it out a bit if you say repeat the
> measurements maybe 10 times for each situation and
> take an average value.

Yes, or even better: let the system run in the operation mode of interest
for let's say about one hour, and continuesly record the "work" (e.g. the
product of time & power) instead of the power itself. This way you got a
very nice average value, which can be easily compared with those of other
operation modes on the same machine.


> I also don't know *what* power save really shuts down on the DVB
> card. The LNB?, the tuner? the bucking step up converter? the ARM7?
> etc.

Well, I don't know either, but that doesn't matter. ;-)

Christian





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