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To: Pete Heist <peteheist@gmail.com>
Cc: make-wifi-fast@lists.bufferbloat.net
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Date: Thu, 22 Feb 2018 13:32:05 +0100
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Subject: Re: [Make-wifi-fast] [PATCH v2] iw: Print TXQ statistics for
	stations and interfaces
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Pete Heist <peteheist@gmail.com> writes:

>> On Feb 22, 2018, at 11:18 AM, Toke H=C3=B8iland-J=C3=B8rgensen <toke@tok=
e.dk> wrote:
>>=20
>> Sample output:
>>=20
>> $ iw dev wlp2s0 station dump -v
>> Station xx:xx:xx:xx:xx:xx (on wlp2s0)
>> [...]
>> 	TXQs:
>> 		TID	qsz-byt	qsz-pkt	flows	drops	marks	overlmt	hashcol	tx-bytes	tx-pack=
ets
>> 		0	0	0	0	0	0	0	0	0		0
>> 		1	0	0	0	0	0	0	0	0		0
>> 		2	0	0	0	0	0	0	0	0		0
>> 		3	0	0	0	0	0	0	0	0		0
>> 		4	0	0	0	0	0	0	0	0		0
>> 		5	0	0	0	0	0	0	0	0		0
>> 		6	0	0	0	0	0	0	0	0		0
>> 		7	0	0	0	0	0	0	0	0		0
>> 		8	0	0	0	0	0	0	0	0		0
>> 		9	0	0	0	0	0	0	0	0		0
>> 		10	0	0	0	0	0	0	0	0		0
>> 		11	0	0	0	0	0	0	0	0		0
>> 		12	0	0	0	0	0	0	0	0		0
>> 		13	0	0	0	0	0	0	0	0		0
>> 		14	0	0	0	0	0	0	0	0		0
>> 		15	0	0	0	0	0	0	0	0		0
>> [...]
>>=20
>> $ iw dev wlp2s0 info
>> Interface wlp2s0
>> 	ifindex 9
>> 	wdev 0x1
>> 	addr xx:xx:xx:xx:xx:xx
>> 	type AP
>> 	wiphy 0
>> 	channel 165 (5825 MHz), width: 20 MHz, center1: 5825 MHz
>> 	txpower 24.00 dBm
>> 	multicast TXQ:
>> 		qsz-byt	qsz-pkt	flows	drops	marks	overlmt	hashcol	tx-bytes	tx-packets
>> 		0	0	72	0	0	0	0	7380		72
>>=20
>
> Could these stats make possible a userspace tool for determining the
> proportion of delay that is introduced by congestion vs by link layer
> issues? Such a tool could be really helpful for network engineers
> wanting to mitigate delay issues and not sure where to best focus
> their efforts...

Well you could combine the amount of backlogged data with the rate
control information and estimate the current queue drain time for each
station I guess. It would technically also be possible to directly
expose the queueing time of the last dequeued packet (as measured by
CoDel) as part of the statistics.

-Toke