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 = "" *) 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 <dcbw redhat com>On Wed, 2010-07-28 at 09:32 -0300, Franco Miceli wrote:Yes, this could be done. If you'd like to do a patch for this there are
> 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?
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 <dcbw redhat com>
> 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 <fmiceli plan ceibal edu uy>
> > 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
> > networkmanager-list gnome org
> > 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