[Ovmsdev] Poor wifi performance

Michael Balzer dexter at expeedo.de
Wed Jan 9 20:08:27 HKT 2019

On analysis of issue #189 I just did a build using the latest upstream/master.

There now are options to enable wifi debug logging:


That may help in debugging our wifi reliability issue if it's still unfixed.


Am 08.01.19 um 05:58 schrieb Mark Webb-Johnson:
> The core issue here (wifi connection being lost, but ESP stack not able to report that to the application - us) is the real culprit. I, like Michael, hope
> that later versions of the ESP IDF can solve this. Once the wear levelling version upgrade bug is fixed, perhaps we can try? I do see this in my home (despite
> the wifi access point being about 2metres from the car), so suspect it is more related to a timeout / interference. For me, it only happens once every few weeks.
> Implementing a facility for fallback to modem even if wifi is up (in the case of connections over wifi failing) is probably a sensible feature. I think we
> would need:
>  1. A way for connection success / failure over a particular transport to be reported to the network layer. Or some way for network layer to access historical
>     statistics.
>  2. Some logic in the network layer to determine wifi is unreliable (presumably based on sequential connections failures without success, over time).
>  3. Some logic in the network layer to determine wifi is reliable again. Perhaps after some time (hours) on modem failover, it could switch back to wifi and
>     try again.
>  4. The switch is done in the network layer itself, and our current default route switching mechanism should support that just fine.
> I guess a config to enable/disable this as a feature.
> But, I would really much rather ‘fix’ the wifi in the first place. It is certainly easier to see if any fix is effective at the moment, with the wifi
> unreliable, than if we had some automatic failover to modem situation.
> Regards, Mark.
>> On 5 Jan 2019, at 2:56 PM, Stephen Casner <casner at acm.org <mailto:casner at acm.org>> wrote:
>> Michael,
>> You're right that we can't depend on the websocket job queue overflow
>> to detect loss of wifi connectivity.  If the improvements in the wifi
>> driver make it sufficiently robust to detect disassociation, then we
>> may not need to do anything else to work around that problem.
>> However, there may well be situations where wifi is able to associate
>> just fine, but there is no connectivity upstream from that point to
>> the server.  To handle such cases I think it would be a good idea to
>> have a signal that both the websocket and server-v[23] can send to
>> netmanager to trigger switching to another path.
>>                                                        -- Steve
>> On Fri, 4 Jan 2019, Michael Balzer wrote:
>>> Steve,
>>> you could have enabled event logging additionally, but there clearly is no event from the wifi driver on the disassociation, or the netmanager would have logged
>>> this as well.
>>> You're probably right in the websocket job queue overflow indicating the loss, but that won't fit as a general canary, as it's only active while at least one
>>> web client is connected.
>>> Another thing you could monitor is the signal quality, or maybe check for a lack of update callbacks? That's CSIRxCallback in esp32wifi.
>>> But that's all working around the underlying wifi blob bug. We first should check if the current IDF blob does a better job.
>>> Regards,
>>> Michael
>>> Am 04.01.19 um 06:15 schrieb Stephen Casner:
>>>> Yesterday I found another instance where I could not ssh to OVMS nor
>>>> ping it.  This time I verified in my router status that the wifi
>>>> association with OVMS was "inactive" (down).  The iPhone app said that
>>>> server-v2 was not hear for 108 minutes.  This time I have a full log
>>>> file covering back to the previous day, which is attached.
>>>> I connected to OVMS with the serial console and the output from the
>>>> serial monitor is appended to the attached log file.  The "wifi stat"
>>>> and "net stat" commands both indicated that the wifi connection was up
>>>> when all the external indications were to the contrary.  Going back
>>>> 108 minutes in the log file corresponds roughly to the first instance
>>>> of "job queue overflow detected".  Perhaps the web server can act as
>>>> the canary in the coal mine?  There is no indication that the wifi
>>>> driver signaled any problem at that time.
>>>> Diagnosing this problem is difficult because the loss of connectivity
>>>> occurs after a day or a few days of operation.  I have not tried the
>>>> current esp-idf yet; I may do that, but I'm not sure how long that
>>>> would need to operate without loss to determine success.
>>>>                                                        -- Steve
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Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
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