Re: [PATCH 0/3] Export TXQ parameters and statistics via nl80211

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

On 2/21/2018 12:00 PM, Toke Høiland-Jørgensen wrote:
> Arend van Spriel <arend.vanspriel@broadcom.com> writes:
>
>> On 2/19/2018 6:02 PM, Toke Høiland-Jørgensen wrote:
>>> This series adds TXQ parameters and statistics that were previously only
>>> available through debugfs to the nl80211 userspace interface and the
>>> cfg80211 kernel interface. Patches for iw to print the statistics and
>>> change the settings are included.
>>
>> So what is your motivation for having this exposed through nl80211.
>> For the average end-user the stats and parameters are fairly fuzzy.
>
> Two reasons, basically:
>
> 1. Visibility and statistics; this is basically the same information
>     that is available at the qdisc layer (with `tc -s qdisc`), but which
>     has been missing on WiFi interfaces ever sine we switched to the TXQ
>     structure. Having this available has been quite valuable for
>     debugging qdisc setups on wired links, and it's not always feasible
>     to ask users to recompile their kernels with debugfs enabled.
>
> 2. Having visibility into the queues from userspace makes it possible to
>     make decisions based upon (e.g.) which stations are currently
>     backlogged. I'm working on a "policy mode" for the airtime fairness
>     scheduler which will use this capability.

I see. Was just wondering whether there were concrete user-space 
applications planned to use the information. Cool.

>> So can we expect some manual in which is described what parameter
>> should be tweaked based on the retrieved statistics.
>
> Heh, not sure I'll promise a whole manual, but I am happy to write a
> blog post (or wiki page if that's better) explaining what these values
> mean and what insight one might gain from them.

My preference would be to have something on wireless.wiki.kernel.org. 
Another option might be to add kerneldoc section for this.

Regards,
Arend