[Cerowrt-devel] what stats do people want from conference wifi?

David Lang david at lang.hm
Sat Feb 7 22:27:39 EST 2015

On Sun, 8 Feb 2015, Dave Taht wrote:

> On Sun, Feb 8, 2015 at 3:48 PM, David Lang <david at lang.hm> wrote:
>> when you say "fairly frequently", is per minute reasonable?
> every 10 sec is easier to deal with. note the cat method I showed is
> inefficient.

I had been thinking in terms of feeding them to syslog for transport and 
timestamping (I haven't looked to see how much data is in each file)

unless these files are lengthy, gathering a couple thousand copies every 10 sec 
sounds reasonable (if they are long, but short lines, we can re-write them to 
fewer, longer lines to make it reasonable), especially if we allow this to run 
with no attempt to sync the runs precisely across APs (so that they do end up 
being pretty spread out across the time)

>> On Sun, 8 Feb 2015, Dave Taht wrote:
>>> I am very interested in per sta stats - rc_stats - captured fairly
>>> frequently - timestamped and kept on per mac order..
>>> cat /sys/kernel/debug/ieee80211/phy*/netdev:*/stations/*/rc_stats
>>> you might also get a good grip on simultaneous users and on user
>>> migration by using this.

we have already been running a per-min job to get the count of connected 
simultaneous users on each ESSID and logging each connection. We haven't done 
much analysis of the data afterwords yet.

David Lang

>>> also I have found the xmit stat to be useful.
>>> On Sun, Feb 8, 2015 at 3:02 PM, David Lang <david at lang.hm> wrote:
>>>> In the next few days I'm going to be building the openwrt images to use
>>>> at
>>>> the SCaLE conference. I will have ~50 APs deployed supporting ~3k
>>>> attendees.
>>>> This will be running on WNDR3700v2 and WNDR3800 APs. Since I am compiling
>>>> the firmware myself, I can add in patches to gather and log stats for
>>>> things
>>>> that are not normally reported
>>>> The wireless network architecture is:
>>>> separate ESSIDs for 2.4 vs 5.
>>>> each band gets bridged to a different VLAN
>>>> the APs are configured not to forward broadcast traffic from one wireless
>>>> client to another on the same AP (although broadcast traffic from one AP
>>>> probably goes out others after hitting the wire now that I think about
>>>> it)
>>>> I have all logs from the APs sent to a central logserver
>>>> I have use rrdtool to catpture normal bandwith/cpu/etc stats
>>>> I also have rrdtool capture how many clients are connected to each ESSID
>>>> every minute.
>>>> What else can I gather related to the wifi?
>>>> I think it would be useful if we could gather info along the lines of
>>>> amount of airtime used
>>>> how much latency is added to packets while waiting to transmit because
>>>> it's
>>>> hearing something else transmit?
>>>> amount of unused airtime available
>>>> average effective bit rate
>>>> percentage of time spent doing broadcasts (things required to operate at
>>>> the
>>>> lowest bit rate)
>>>> Part of the reason that I compile my own firmware images is that I
>>>> completely disable connection tracking in the kernel (because clients may
>>>> move from one AP to another in the middle of a connection it's a waste of
>>>> cpu and memory to track), and as a result of these optimizations, there
>>>> is
>>>> actually quite a bit of CPU available. The boxes almost never hit 20% cpu
>>>> utilization, so there's quite a bit available to gather other stats.
>>>> some of the stats I gather are in messages spit out by the kernel, others
>>>> from scrips running on the box querying things in /proc or /sys, and
>>>> others
>>>> from watching logs and summarizing them once a minute. I even have a
>>>> process
>>>> that goes threough all the connection logs for the duration of the show
>>>> and
>>>> graph how many unique MAC addresses we've seen and a breakdown into the
>>>> different vendor prefixes. If there's a way to get the data, I can
>>>> support
>>>> it.
>>>> If there are fq_codel stats that people would find interesting in this
>>>> environment, I can gather those as well (both on the APs and on the
>>>> Debian
>>>> based firewall/gateway)
>>>> David Lang
>>>> _______________________________________________
>>>> Cerowrt-devel mailing list
>>>> Cerowrt-devel at lists.bufferbloat.net
>>>> https://lists.bufferbloat.net/listinfo/cerowrt-devel

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