Dan,
If I undersand correctly, what you say is that we "count" the times the
signal SCAN_RESULTS gets emitted. Please correct me if I'm wrong.
Also you mention to request two back to back scans at startup. My question
on this is:
- Is the method auto_activate_device (gpointer user_data) the one in charge
of initially activating all interfaces?
- If so, is it here where you say we should use the method
request_wireless_scan twice in order to get two scans scheduled?
You say to reduce the constant SCAN_INTERVAL_MIN to 11, In any case the
initial value of that constant is 0 so I think you mean to increase it,
right?
If the start code for an interface is within auto_activate_device, I don't
see where the initial scans are being requested. What I understand NM does,
is a lot of processes executed in parallel, some of them (or most) triggered
by different signals. What I mean by this is since I don't see any scan
request on auto_activate_device -and I think that here is where the wireless
iface gets activated- I'm assuming that the scan requests are made by
another process running in parallel.
If this is the case, I thought one could -within auto_activate_device- wait
and count the times the SCAN_RESULTS signal gets emitted, and after X
emissions, pass through to get_best_auto_connection.
A pseudocode for this would be something like this:
auto_activate_device (gpointer user_data)
{
ActivateData *data = (ActivateData *) user_data;
NMPolicy *policy;
g_slist_free (iter);
..........
}
iter = next;
}
WHILE SCAN-COUNT < X DO {} /*SCAN-COUNT gets updated in the callback
function of the emitted SCAN_RESULT signal*/
best_connection = nm_device_get_best_auto_connection (data->device,
connections, &specific_object);
..........
out:
/* Remove this call's handler ID */
policy->pending_activation_checks = g_slist_remove
(policy->pending_activation_checks, data);
g_object_unref (data->device);
g_free (data);
return FALSE;
}
Then in the callback function to the scan_results:
supplicant_iface_scan_results_cb (NMSupplicantInterface *iface,
guint32 num_results,
NMDeviceWifi *self)
{
priv = getPrivate(self);
priv->SCAN-COUNT++;/*Defined previously within NMDeviceWIFI*/
if (num_results == 0) {
/* ensure that old APs get culled, which otherwise only
* happens when there are actual scan results to process.
*/
cull_scan_list (self);
}
}
----------------------------------------------------------------------------------------------------------
What do you think about this? Am I getting it all wrong?
Thank you very much.
Cheers
2010/7/28 Dan Williams <[email protected]>
> On Wed, 2010-07-28 at 09:32 -0300, Franco Miceli wrote:
> > Dan,
> >
> > Thanks for your answer. I see what you say. You can request X number
> > of scans without being sure that the firmware will execute them.
> >
> > I understand that to do what I say, that would be mandatory. But in
> > order to mitigate the problem of not seeing all AP in range at the
> > start of the autoconnect feature, could one delay the autoconnect
> > algorithm so that it would wait for several scans to be made?
>
> Yes, this could be done. If you'd like to do a patch for this there are
> a few ways you could go about it.
>
> Since we don't get reliable scan indications, we should just do two
> back-to-back scans on startup. The problem is trying to figure out when
> they are *done*. That requires both a 10 second timeout after
> requesting the scan and a 2-second backoff timer that gets reschedule
> for two more seconds each time a scan result comes in while the 10
> second timeout timer is active. If either of the 10-second timeout or
> the 2-second backoff timer fire, then we increment a 'guint32 num_scans'
> variable in NMDeviceWifiPrivate.
>
> Then, reduce SCAN_INTERVAL_MIN to 11 (so it doesn't overlap with the
> 10-second backoff timer).
>
> Next, put a check in real_get_best_auto_connection() to return NULL if
> num_scans < 2 (so we do 2 scans before allowing autoconnect).
>
> Finally, we need a way to tell NMPolicy to retrigger autoconnect
> checking, which probably means another signal on NMDeviceInterface
> called "recheck-autoactivate" that gets emitted when num_scans changes
> to 2. The Policy listens to this variable and calls
> schedule_activate_check() when the signal is emitted.
>
> Dan
>
> > I say this because I've seen that after just ten seconds of sugar
> > being started, almost every AP is shown in the neighbour view (sort of
> > an AP list). If we could delay the time where NM_autoconnect gets
> > called at startup, I think this could be dealt with.
> >
> > I appreciate any feedback you can provide on this topic.
> >
> > Thanks once again for your answers.
> >
> > Cheers,
> >
> >
> >
> > 2010/7/28 Dan Williams <[email protected]>
> > On Fri, 2010-07-16 at 09:30 -0300, Franco Miceli wrote:
> > > So far, trying to get this problem solved, I have made a
> > initscript
> > > that runs before NM. This script enables the wireless
> > interface and
> > > performs a couple of scans (iwlist).
> > >
> > > Doing this (which performs as asked, finding almost all the
> > networks
> > > in range), doesn't cause any effect on NM. NM still shows
> > only a few
> > > of the available networks at startup.
> > >
> > > Is this something that can be dealt with at device autostart
> > or
> > > something like that. I would really appreciate if anyone
> > could point
> > > me at any direction, since I'm a bit lost inside the NM
> > code. Maybe
> > > the function that starts the network interfaces, and/or
> > where does NM
> > > take the scan results from at startup.
> >
> >
> > We should probably do more than on initial scan, but there's a
> > big
> > problem... WEXT does not really give us any information about
> > scan
> > outcomes. Sometimes the drivers and/or firmware will accept
> > the scan
> > request and then cancel it later due to internal operations.
> > And if
> > that happens, WEXT doesn't have the ability to notify
> > userspace that the
> > scan request failed.
> >
> > nl80211/cfg80211 have the ability to make this somewhat
> > better, but only
> > for drivers that have been ported to cfg80211. Libertas
> > (which the OLPC
> > XO-1 uses) is not yet full ported to cfg80211 in the 2.6.35
> > kernel.
> >
> > So once we can use cfg80211, even then we need to make sure
> > the drivers
> > get fixed up to report internal scan cancellations to
> > userspace. Then
> > we need the supplicant to push that notification up to clients
> > too.
> >
> > Until then, we can't be sure whether any scan request we send
> > to the
> > supplicant is actually successfully triggered or not, which
> > means we
> > don't know whether we need to try again.
> >
> > Dan
> >
> >
> > > Thanks in advance for any answers anyone can provide.
> > >
> > > Cheers
> > >
> > > 2010/7/13 Franco Miceli <[email protected]>
> > > Hi,
> > >
> > > I have the following question: how many scans does
> > NM wait
> > > until it calls the autoconnect
> > (real_get_best_autoconnection)
> > > feature?
> > >
> > > I ask this because the card the hardware I am
> > currently
> > > testing (OLPC XO-1) has doesn't report all the
> > wireless AP in
> > > range immediately.
> > > That's why I want to either add a waiting period or
> > something
> > > like that in order to hold on so that all the AP in
> > range are
> > > available for choosing.
> > >
> > > In order to do so, I need to know where in the
> > source code I
> > > can find the line/s where the autoconnection gets
> > called.
> > >
> > > If anyone knows where to look for I would really
> > appreciate
> > > your feedback.
> > >
> > > Thanks for your answers.
> > >
> > > Cheers
> > >
> > >
> > >
> > > --
> > > Ing. Franco Miceli
> > > CITS - Plan Ceibal - Investigación & Desarrollo
> > > Av. Italia 6201 - Montevideo, Uruguay
> > > CP: 11500
> > > Tel: (598 2) 601 5773 int.: 2227
> >
> > > _______________________________________________
> > > networkmanager-list mailing list
> > > [email protected]
> > > http://mail.gnome.org/mailman/listinfo/networkmanager-list
> >
> >
> >
> >
> >
> > --
> > Ing. Franco Miceli
> > CITS - Plan Ceibal - Investigación & Desarrollo
> > Av. Italia 6201 - Montevideo, Uruguay
> > CP: 11500
> > Tel: (598 2) 601 5773 int.: 2227
>
>
>
--
Ing. Franco Miceli
CITS - Plan Ceibal - Investigación & Desarrollo
Av. Italia 6201 - Montevideo, Uruguay
CP: 11500
Tel: (598 2) 601 5773 int.: 2227
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