From: Alan Jenkins <alan.christopher.jenkins@gmail.com>
To: Sebastian Moeller <moeller0@gmx.de>
Cc: cerowrt-devel <cerowrt-devel@lists.bufferbloat.net>
Subject: Re: [Cerowrt-devel] SQM and PPPoE, more questions than answers...
Date: Thu, 19 Mar 2015 13:49:44 +0000 [thread overview]
Message-ID: <550AD3F8.1000904@gmail.com> (raw)
In-Reply-To: <E69E8133-E4BD-420A-B3E0-0E6D5550DE6A@gmx.de>
Hi Seb, I have one last suspicion on this topic
On 19/03/15 08:29, Sebastian Moeller wrote:
> My question still is, is the bandwidth sacrifice really necessary or is this test just showing a corner case in simple.qos that can be fixed. I currently lack enough time to tackle this effectively.
>>>> 2) SQM on ge00 shows better latency under load (LUL), the LUL
>>>> increases for ~2*fq_codels target so 10ms, while SQM on pppeo-ge00
>>>> shows a LUL-increase (LULI) roughly twice as large or around 20ms.
>>>>
>>>> I have no idea why that is, if anybody has an idea please chime
>>>> in.
>> I saw the same, though with higher difference for egress rate. See first three files here:
>>
>> https://www.dropbox.com/sh/shwz0l7j4syp2ea/AAAxrhDkJ3TTy_Mq5KiFF3u2a?dl=0
>>
>> [netperf-wrapper noob puzzle: most of the ping lines vanish part-way through. Maybe I failed it somehow.]
> This is not your fault, the UDP probes net-perf wrapper uses do not accept packet loss, once a packet (I believe) is lost the stream stops. This is not ideal, but it gives a good quick indicator of packet loss for sparse streams ;)
Thinking about this, I remembered the issue that sqm de-priotises ICMP
ping. (Back when I used betterspeedtest and netperf-runner, I did
assume this would be an issue).
I also notice that my test with eth1 (disabling classification) is the
only one where UDP ping (including UDP EF) is visible for any time at
all. (ok, pppoe-wan shows UDP BK, and it very clearly gets higher
latency as I would expect).
So I don't know if your results were clearer, but the results I showed
so far should be treated as a measurement problem.
>>> Once SQM on ge00 actually dives into the PPPoE packets and
>>> applies/tests u32 filters the LUL increases to be almost identical to
>>> pppoe-ge00’s if both ingress and egress classification are active and
>>> do work. So it looks like the u32 filters I naively set up are quite
>>> costly. Maybe there is a better way to set these up...
>> Later you mentioned testing for coupling with egress rate. But you didn't test coupling with classification!
> True, I was interesting in getting the 3-tier shaper to behave sanely, so I did not look at the 1-tier simplest.qos.
>
>> I switched from simple.qos to simplest.qos, and that achieved the lower latency on pppoe-wan. So I think your naive u32 filter setup wasn't the real problem.
> Erm, but simplest.qos is not using the relevant tc filters, so the these could still account for the issue; that or some loss due to the 3 htb shapers...
next prev parent reply other threads:[~2015-03-19 13:49 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-10-11 23:12 Sebastian Moeller
2014-10-15 0:03 ` Sebastian Moeller
2014-10-15 12:02 ` Török Edwin
2014-10-15 13:39 ` Sebastian Moeller
2014-10-15 17:28 ` Dave Taht
2014-10-15 19:55 ` Sebastian Moeller
2015-03-18 22:14 ` Alan Jenkins
2015-03-19 2:43 ` David Lang
2015-03-19 3:11 ` Dave Taht
2015-03-19 8:37 ` Sebastian Moeller
2015-03-19 8:29 ` Sebastian Moeller
2015-03-19 9:42 ` Alan Jenkins
2015-03-19 9:58 ` Sebastian Moeller
2015-03-19 13:49 ` Alan Jenkins [this message]
2015-03-19 13:59 ` Toke Høiland-Jørgensen
2015-03-19 14:01 ` Dave Taht
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: https://lists.bufferbloat.net/postorius/lists/cerowrt-devel.lists.bufferbloat.net/
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=550AD3F8.1000904@gmail.com \
--to=alan.christopher.jenkins@gmail.com \
--cc=cerowrt-devel@lists.bufferbloat.net \
--cc=moeller0@gmx.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox