Comment 109 for bug 414560

On Sun, Nov 1, 2009 at 3:34 AM, Rachel Greenham
<email address hidden> wrote:
> Howard Chu wrote:
>> That was explained in one of the previous discussions. The ath9k is an
>> a/b/g/n interface and has a lot more channels to scan, and it's the
>> extra time required to scan these additional channels that causes the
>> association to time out. Or that's the theory anyway; the ath9k driver
>> seems to still have plenty of problems of its own without NM adding to
>> them.
>>
>>
> Well, it's still the case that installing the backports, and otherwise
> changing *nothing*, so I'm still using network-manager, i get better
> signal strength and no loss of connection and good transfer rates.
>
> So I reckon while the NM issues *may* be real issues to some people,
> they're not the big story here.
>

LBM (linux-backports-modules) is based on the cutting-edge of
wireless-testing kernel tree via compat-wireless.
http://wireless.kernel.org/en/users/Download#Getting_compat-wireless_on_Ubuntu

If you follow it here:
http://git.kernel.org/?p=linux/kernel/git/linville/wireless-testing.git;a=summary

you'd see that there are quite a few changes that have gone recently into ath9k.
Maybe, that's fixed some of the older issues that we've been
discussing here - I'm yet to install karmic.

Point being that the shipped kernel drivers and lbm drivers may be worlds apart.

@Christopher,
the problem of background scanning is compounded by the fact that
ath9k takes a lot of time to complete the scan.
It's improving at a snail's pace - to add to that, the atheros guys
haven't been all that helpful either.
I'm subscribed to both wireless-devel and ath9k-devel lists.

The meaning of 'perceived' loss is wrt NM - it thinks the connection
is alive while the scan is progressing.
I agree that in reality, the tcp connections (so do udp - dns lookups
almost never work during a scan) drop like crazy during scans - even I
have to switch to wired whenever using skype or anything that requires
sustained connectivity.

@Howard,
The scanning process is a required process - otherwise, you can never
come to know about what networks are available in your vicinity.
However, the way it's implemented seems to be problematic.

Unfortunately, for me, wicd has never worked :(
And I'm not all that hopeful about NM either.

Kunal