Re: Reporting firmware stats to ethtool

[Arend van Spriel <arend@broadcom.com>]

On 08/08/2014 06:11 PM, Ben Greear wrote:
> On 08/08/2014 08:55 AM, Dave Taht wrote:
>> On Fri, Aug 8, 2014 at 8:42 AM, Ben Greear <greearb@candelatech.com> wrote:
>>> On 08/08/2014 02:06 AM, Kalle Valo wrote:
>>>> Ben Greear <greearb@candelatech.com> writes:
>>>>
>>>>> I'm working on a patch to report the stats seen in debugfs/...ath10k/fw_stats
>>>>> as ethtool stats, somewhat similar to how ath9k does it.
>>>>>
>>>>> I notice that my user-space tool is reporting huge numbers because
>>>>> the stats are reset to zero when firmware restarts, and so my tool
>>>>> thinks the stats wrapped.
>>>>>
>>>>> I can fix my tool easily enough, but I first wanted to see if
>>>>> anyone had strong feelings about keeping the stats from resetting
>>>>> to zero by storing history and calculating diffs in the driver.
>>>>>
>>>>> I think my preference is to punt this to user-space, but if
>>>>> someone feels otherwise, please let me know sooner than later.
>>>>
>>>> I also prefer to have this in user space, but how does user space know
>>>> when the stats have been zeroed?
>>>
>>> Poll often enough that it cannot increment more than 2 billion (or other large number)
>>> between polls, and then if polled value is less than previous (and difference is > 2 billion),
>>> we know we had a reset and not a wrap.
>>
>> I do kind of prefer 64 bit counters in the general case. Nuke it from
>> orbit, it's the only way to be sure.
>
> It's 64-bit to user-space, but that means nothing because firmware
> uses 32-bit (or even 16 bit in some cases, probably) internally.
> A great deal of counters are the same, so be very careful when
> trying to keep long term counters grabbed from firmware/drivers/hardware.
>
> And, stations come and go when you re-associate, so all sorts of wifi counters
> reset themselves all the time...

Does ath driver notify mac80211 about firmware restart, ie. through 
ieee80211_restart_hw(). If only user-space could get that info.

Gr. AvS

> Thanks,
> Ben
>
>>
>>> User-space stats will not be perfect in the case of firmware resets, or resets
>>> after the 'large number', but nothing is going to make it perfect, and in
>>> practice, this seems good enough.
>>>
>>> Thanks,
>>> Ben
>>>
>>> --
>>> Ben Greear <greearb@candelatech.com>
>>> Candela Technologies Inc  http://www.candelatech.com
>>>
>>>
>>> _______________________________________________
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>>
>>
>>
>
>