Transport-level protocols in user space

Posted Jun 30, 2016 5:37 UTC (Thu) by marcH (subscriber, #57642)
In reply to: Transport-level protocols in user space by marcH
Parent article: Transport-level protocols in user space

> > I suspect a lot of bug reports will go straight to /dev/null once it is clear that it is a TOU TCP connection.

> Bug reports from Joe Random getting ignored: what's new?

Example: one of the many, spot reports of bufferbloat. A very simple one. Reported in 2004, more than 5 years before Jim Gettys thoroughly studied bufferbloat and gave it a catchy name. According to https://lwn.net/Articles/617070/, this had been ignored until 2014.

I find nothing wrong with ignoring bug reports from nobodies; the reputation system serves a useful filtering purpose and this is the way it's supposed to work. Everything is fine... as long as no one pretends that all reports get looked at.

> TOU-related bug reports from Facebook, Amazon or Google coming with tentative fix attached? I bet they will be looked at.

Transport-level protocols in user space

Posted Jun 30, 2016 13:33 UTC (Thu) by paulj (subscriber, #341) [Link] (5 responses)

Interesting blast from the past. After re-reading the wider comment threads there, it is sad that this is _still_ happening:

3: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000

Fedora 24. qdisc + 1k qlen.

:( :( :(

(And yeah, I've raised bugs in the past, given suggested scripts for NM to set lower qlen - rejected).

Transport-level protocols in user space

Posted Jul 5, 2016 9:39 UTC (Tue) by Lennie (subscriber, #49641) [Link] (4 responses)

It's amazing to see something like this:

"Going back to what Marc said in an earlier e-mail about having txqueuelen in the unit of bytes rather than packets to provide a fixed queueing delay in ms rather than packets. Maintaining txqueuelen in ms would be an ideal solution, but probably hard to achieve in practice."

That is actually what CoDel does, drop some packets when the length of the queue measured _in time_ becomes to long (simplification).

Transport-level protocols in user space

Posted Jul 5, 2016 9:48 UTC (Tue) by paulj (subscriber, #341) [Link] (3 responses)

Yes, and the response to my Fedora bug on lowering the default qdisc qlen (or setting it according to the negotiated bitrate - at least the initial one) was that a much better fix would just be to switch over to CoDel. Which is fair enough. And it has happened for the default for ethernet:

2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc fq_codel state UP group default qlen 1000

But wlan still seems stuck on qdisc and a massive qlen. :(

Transport-level protocols in user space

Posted Jul 17, 2016 11:45 UTC (Sun) by mtaht (subscriber, #11087) [Link] (2 responses)

Assembling the resources, ideas, code, people, etc, to tackle wifi's bufferbloat issues in linux has taken a long time.

but we are making serious progress, now on two chipsets.

http://blog.cerowrt.org/post/fq_codel_on_ath10k/

https://blog.tohojo.dk/2016/06/fixing-the-wifi-performanc...

Coming soon to a kernel tree near you, I hope.

Transport-level protocols in user space

Posted Jul 17, 2016 14:57 UTC (Sun) by Lennie (subscriber, #49641) [Link]

You folks are my heroes. Keep up the awesome work !

Transport-level protocols in user space

Posted Jul 17, 2016 21:32 UTC (Sun) by flussence (guest, #85566) [Link]

That looks amazing. I recognise that horrible mess of a graph: it's what my home network does as soon as someone else on it starts watching videos or whatever...