Re: 31-rc3-mmotm0716 - wonky wireless statistics..

From: Valdis . Kletnieks
Date: Mon Aug 03 2009 - 23:43:38 EST


On Wed, 29 Jul 2009 09:19:12 +0200, Johannes Berg said:

> > > # cat /proc/net/wireless
> > > Inter-| sta-| Quality | Discarded packets | Missed | WE
> > > face | tus | link level noise | nwid crypt frag retry misc | beacon | 22
> > > wlan0: 0000 63. -47. -256 0 0 0 0 0
> > > wlan1: 0000 0 0 0 0 0 0 0 0
> > > wlan2: 0000 0 0 0 0 0 0 0 0

> and since we have dBm for the signal strength (and dBm is "all or
> nothing") you get -256 since we don't fill noise right now.
>
> However, it goes on like this:
> stats->qual.updated & IW_QUAL_NOISE_UPDATED ? '.' : ' '
>
> so you're right -- the tool shouldn't be using the value unless followed
> by a dot (".").

OK, went back and checked a -mmotm0702 kernel, and there I see:

cat /proc/net/wireless
Inter-| sta-| Quality | Discarded packets | Missed | WE
face | tus | link level noise | nwid crypt frag retry misc | beacon | 22
wlan0: 0000 64. -46. -127. 0 0 0 0 0 0
wlan1: 0000 0 0 0 0 0 0 0 0 0
wlan2: 0000 0 0 0 0 0 0 0 0 0

so yes, it appears that the userspace program (gkrellm-wifi) is failing to
notice the lack of a trailing '.'. Looks like I need to write a patch and push
it upstream, make it do something sensible with the S/N ratio when N is
missing. Too bad probably no easy way to compute an estimate based on the level
and link-quality values....

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