Re: [PATCH v2 00/22] brcmsmac: Tx rework and expanded debug/trace support

[Daniel Wagner <wagi@monom.org>]

Hi Seth,

On 21.11.2012 15:35, Seth Forshee wrote:
> On Wed, Nov 21, 2012 at 10:56:47AM +0100, Daniel Wagner wrote:
>> On 21.11.2012 10:44, Arend van Spriel wrote:
>>> On 11/20/2012 11:45 PM, Daniel Wagner wrote:
>>>>>
>>>>> I am currently not able to reproduce a complete loss of connectivity.
>>>>
>>>> I fear it is a heisenbug. After turning the tracing off I was able to
>>>> reproduce it very easily.
>
> Just to clarify, you see the issue using the same kernel but without
> trace-cmd running?

Yes, exactly.

> If so you might try disabling the brcmsmac_tx
> tracepoing, which probably adds the most overhead, and see if you can
> reproduce the problem. It obviously won't give as much information but
> maybe it will still provide some clues.

Will do. To clarify what I mean with 'connectivity' loss, is that 
ConnMan/wpa_s still think everything is fine but nothing works anymore. 
So it could be a combination of issues which sums up to this behavior. 
I'll spend some more time to gather better information.

>>> That is too bad. I always wondered about the tracing overhead affecting
>>> reproducibility. So the trace that you uploaded was not showing the
>>> issue of connection loss you are having?
>>
>> The trace does only show that the throughput goes considerable down and the
>> download might even stop shortly but overall the system recovers again.
>>
>> Well, to add some random observation here, I think I see the same pattern
>> when using MacOS (yeah, sorry, dual boot). With MacOS the link is usable but
>> the throughput sometimes really goes down and recovers then. Obviously, this
>> could also be something else, I tried it with an pretty old AP which only
>> support 11g. Using the 11g AP didn't show this behavior.
>>
>> My 'test' setup is following: I downloaded a larger file and let a youtube
>> video play. With tracing enabled the download and the playback did work nicely.
>>
>> Without tracing enabled playing back only a youtube video was 'triggering'
>> the problem. It downloads a few seconds of content in a burst and then the playback
>> starts. Under normal conditions, the app will continue downloading the video at a
>> lower rate. But this normally doesn't happen right now. Often it will just stop
>> working and often the connection is completely blocked, e.g. pinging a host
>> wont work.
>
> I'll see if I can reproduce, but if it's specific to the AP then I may
> not have any luck. Don't expect to hear much from me until next week
> though; I'm on holiday starting today and will be visiting family.

Enjoy!

cheers,
daniel