From: "Toke Høiland-Jørgensen" <toke@toke.dk>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: make-wifi-fast@lists.bufferbloat.net, linux-wireless@vger.kernel.org
Subject: Re: [Make-wifi-fast] [PATCH v3] mac80211: Dynamically set CoDel parameters per station
Date: Thu, 06 Apr 2017 17:58:25 +0200 [thread overview]
Message-ID: <87efx5ply6.fsf@alrua-kau> (raw)
In-Reply-To: <1491475915.10124.75.camel@edumazet-glaptop3.roam.corp.google.com> (Eric Dumazet's message of "Thu, 06 Apr 2017 03:51:55 -0700")
Eric Dumazet <eric.dumazet@gmail.com> writes:
> On Thu, 2017-04-06 at 11:38 +0200, Toke Høiland-Jørgensen wrote:
>
>> +
>> + if (thr && thr < STA_SLOW_THRESHOLD * sta->local->num_sta) {
>> + sta->cparams.target = MS2TIME(50);
>> + sta->cparams.interval = MS2TIME(300);
>> + sta->cparams.ecn = false;
>> + } else {
>> + sta->cparams.target = MS2TIME(20);
>> + sta->cparams.interval = MS2TIME(100);
>> + sta->cparams.ecn = true;
>> + }
>> +}
>
> Why ECN is flipped on/off like that ?
The reasoning is that at really low bandwidths we're better off dropping
the packet and getting potentially latency-sensitive data queued behind
it through (see Dave's various rants with the topic "Packets have
mass").
> ECN really should be an admin choice.
Well, the trouble is that the mac80211 queues don't really have an admin
interface currently. So it'll always use ECN (before this change).
> Also, this change in parameters looks suspect to me, adding a bimodal
> behavior. I would consult Kathleen and Van on this possibility.
Yeah, I agree that it's somewhat of a hack from a theoretical point of
view. I've also been experimenting with Kathy's recommended way of
dealing with bursty MACs (turning off CoDel when there's less than an
MTU's worth of data left), but have not had a lot of success with it.
Guess I can go back and try some variants on that, unless someone else
has better ideas?
-Toke
next prev parent reply other threads:[~2017-04-06 15:58 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-10 19:33 [Make-wifi-fast] [PATCH] " Toke Høiland-Jørgensen
2016-09-10 19:54 ` Jim Gettys
2016-09-10 20:09 ` Toke Høiland-Jørgensen
2016-09-11 3:16 ` Loganaden Velvindron
2016-09-11 0:09 ` kbuild test robot
2017-04-05 16:18 ` [Make-wifi-fast] [PATCH v2] " Toke Høiland-Jørgensen
2017-04-06 7:56 ` kbuild test robot
2017-04-06 8:45 ` kbuild test robot
2017-04-06 9:38 ` [Make-wifi-fast] [PATCH v3] " Toke Høiland-Jørgensen
2017-04-06 10:51 ` Eric Dumazet
2017-04-06 15:58 ` Toke Høiland-Jørgensen [this message]
2017-04-13 18:26 ` Dave Taht
2017-05-17 14:06 ` Johannes Berg
2017-05-19 9:27 ` Toke Høiland-Jørgensen
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