[maemo-users] Steve's Ranty Review #1: N800 ogg support

From: Frédéric Crozat fred at crozat.net
Date: Sun Oct 21 22:18:37 EEST 2007
Le samedi 20 octobre 2007 à 10:24 +0300, Kalle Valo a écrit :
> "ext Frederic Crozat" <fred at crozat.net> writes:
> > Just curious : is the n800 really supposed to last "days" when connected
> > via Wifi (with full WLAN Power Save mode enabled), without any
> > disconnect timeout and anything doing network access on the wifi link ?
> Short answer: Yes, even with the default WLAN PSM settings.

Thanks you. So, let's investigate to find what is causing those bad

> Long answer: It depends on your network. Here are few items which
> mostly affect WLAN power consumption:
> o N800 transmitting something periodically (once in a minute is not
>   bad, once in a second is really bad, Google talk has 30s interval
>   which is ok).

I've disabled any program which might do network query in background.

> o Buggy AP which does not support WLAN PSM properly.

My AP (Freebox, an ISP set-top-box) seems to support WLAN PSM properly.
I also have a Fonera. Is there any way to check, from n800 side, if WLAN
PSM isn't working properly ? (I've enabled full PSM and pings are still

> o distance to AP (WLAN background scan will kick in if the signal level is
>   -75 dBm or less)

Not a problem here, I'm in about 2 to 5 meters of AP.

> o Lots of broadcast and multicast packets on the network (like
>   Windows samba broadcasts).

No Windows (nor Samba) on the network.

However, I tried to run tcpdump on n800 to see what is going on.

It seems Nintendo Wii "standby mode" is causing arp and DNS query, seen
on n800, every 10 minutes.

Since I have two AP available, I'll try to configure both n800 and Wii
to use separate networks, to check if it improves situation.

> Also WLAN settings (beacon and DTIM interval) affect power
> consumption, but not before the issues I have listed above are ruled
> out. And this was only about issues related to WLAN, if there are
> other processes waking up the CPU that will naturally affect the
> standby time.

I've learned this the hard way with Canola last year, with my 770 :)
Now, I make sure there is no server or background stuff running when
doing tests..

> For the background scan there are going to be some optimisations in
> OS2008, for example the limit will be lowered to -85 dBm.


> > When I check battery applet (which is really great btw), I'm never sure
> > if the "in use" time is applicable when being idle AND wifi connected.
> The applet does not provide WLAN standby time at all, sorry.


> > I know I disable network auto-connect and set disconnect timeout to 5min
> > because I had bad experience with first IT2007 version (before full WLAN
> > Power Save mode gconf key were given here). Maybe I should try it
> > again..
> I think you should, you might be pleasently surprised. If not, I would
> guess that after a bit of investigation you might find what's causing
> the high power consumption. tcpdump is your friend. And if you have
> any questions, post them here.

Can we expect any improvement when changing WLAN power from 100mA to
10mA ? 

Frédéric Crozat 

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