From: Eric Dumazet <eric.dumazet@gmail.com>
To: Nandita Dukkipati <nanditad@google.com>
Cc: Tomas Hruby <thruby@google.com>, netdev <netdev@vger.kernel.org>,
codel@lists.bufferbloat.net
Subject: Re: [Codel] [RFC v2] fq_codel : interval servo on hosts
Date: Tue, 04 Sep 2012 17:34:15 +0200 [thread overview]
Message-ID: <1346772855.13121.40.camel@edumazet-glaptop> (raw)
In-Reply-To: <CAB_+Fg5xPRqEZNdH0mYogmm4LitMvycSLB-X1_7ryn4RY9FvSA@mail.gmail.com>
On Tue, 2012-09-04 at 08:10 -0700, Nandita Dukkipati wrote:
> The idea of using srtt as interval makes sense to me if alongside we
> also hash flows with similar RTTs into same bucket. But with just the
> change in interval, I am not sure how codel is expected to behave.
>
> My understanding is: the interval (usually set to worst case expected
> RTT) is used to measure the standing queue or the "bad" queue. Suppose
> 1ms and 100ms RTT flows get hashed to same bucket, then the interval
> with this patch will flip flop between 1ms and 100ms. How is this
> expected to measure a standing queue? In fact I think the 1ms flow may
> land up measuring the burstiness or the "good" queue created by the
> long RTT flows, and this isn't desirable.
>
Well, how things settle with a pure codel, mixing flows of very
different RTT then ?
It seems there is a high resistance on SFQ/fq_codel model because of the
probabilities of flows sharing a bucket.
So what about removing the stochastic thing and switch to a hash with
collision resolution ?
next prev parent reply other threads:[~2012-09-04 15:34 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-31 6:55 [Codel] fq_codel : interval servo Eric Dumazet
2012-08-31 13:41 ` Jim Gettys
2012-08-31 13:50 ` [Codel] [RFC] fq_codel : interval servo on hosts Eric Dumazet
2012-08-31 13:57 ` [Codel] [RFC v2] " Eric Dumazet
2012-09-01 1:37 ` Yuchung Cheng
2012-09-01 12:51 ` Eric Dumazet
2012-09-04 15:10 ` Nandita Dukkipati
2012-09-04 15:25 ` Jonathan Morton
2012-09-04 15:39 ` Eric Dumazet
2012-09-04 15:34 ` Eric Dumazet [this message]
2012-09-04 16:40 ` Dave Taht
2012-09-04 16:54 ` Eric Dumazet
2012-09-04 16:57 ` Eric Dumazet
2012-08-31 15:53 ` [Codel] fq_codel : interval servo Rick Jones
2012-08-31 16:23 ` Eric Dumazet
2012-08-31 16:59 ` Dave Taht
2012-09-01 12:53 ` Eric Dumazet
2012-09-02 18:08 ` Dave Taht
2012-09-02 18:17 ` Dave Taht
2012-09-02 23:28 ` Eric Dumazet
2012-09-02 23:23 ` Eric Dumazet
2012-09-03 0:18 ` Dave Taht
2012-08-31 16:40 ` Jim Gettys
2012-08-31 16:49 ` Jonathan Morton
2012-08-31 17:15 ` Jim Gettys
2012-08-31 17:31 ` Rick Jones
2012-08-31 17:44 ` Jim Gettys
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