[aqm] ping loss "considered harmful"

Dave Taht <dave.taht@gmail.com> Mon, 02 March 2015 03:57 UTC

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From: Dave Taht <dave.taht@gmail.com>
To: "cerowrt-devel@lists.bufferbloat.net" <cerowrt-devel@lists.bufferbloat.net>, "aqm@ietf.org" <aqm@ietf.org>, bloat <bloat@lists.bufferbloat.net>
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Subject: [aqm] ping loss "considered harmful"
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On this thread over here, an otherwise pretty clueful user chose
openwrt's qos-scripts over the sqm-scripts, because sqm-scripts had
*higher ping loss*.


http://forums.dlink.com/index.php?topic=61634.msg251125#msg251125

(I note that both fq_codel enabled QoS systems outperformed
streamboost by a lot, which I am happy about)

wow. It never registered to me that users might make a value judgement
based on the amount of ping loss, and in looking back in time, I can
think of multiple people that have said things based on their
perception that losing pings was bad, and that sqm-scripts was "worse
than something else because of it."

sqm-scripts explicitly *deprioritizes* ping. In particular, this
reduces the impact of ping floods from ipv6 to your entire /64, or to
your whole ipv4, fairly well. And I had made the point that
prioritizing ping was a bad idea here (including some dripping sarcasm
later in the piece).

http://www.bufferbloat.net/projects/cerowrt/wiki/Wondershaper_Must_Die

but wow, it never occurred to me - in all these years - that ping was
the next core metric on simple tests. I can be really dumb.

I use netperf-wrapper and tend to ignore most of the ping data, but
certainly on some benchmarks we have published ping doesn't look as
good as the other stuff, *because it is deprioritized below all the
other traffic*. Not strictly rate limited - as some systems do by
default, including openwrt, which is impossible to get right - just
deprioritized....

How can we fix this user perception, short of re-prioritizing ping in
sqm-scripts?

-- 
Dave Täht
Let's make wifi fast, less jittery and reliable again!

https://plus.google.com/u/0/107942175615993706558/posts/TVX3o84jjmb