From: "Bless, Roland (TM)" <roland.bless@kit.edu>
To: Luca Muscariello <luca.muscariello@gmail.com>
Cc: Jonathan Morton <chromatix99@gmail.com>,
Mikael Abrahamsson <swmike@swm.pp.se>,
bloat <bloat@lists.bufferbloat.net>
Subject: Re: [Bloat] when does the CoDel part of fq_codel help in the real world?
Date: Tue, 27 Nov 2018 13:22:38 +0100 [thread overview]
Message-ID: <a63a38d1-5b2f-a605-6592-a21a37af0395@kit.edu> (raw)
In-Reply-To: <CAHx=1M6+-vL6CPYtJcTg3B-dzTLTnrDvim0mNNEh7PtKXnhQ6A@mail.gmail.com>
Hi,
Am 27.11.18 um 12:58 schrieb Luca Muscariello:
> A buffer in a router is sized once. RTT varies.
> So BDP varies. That’s as simple as that.
> So you just cannot be always at optimum because you don’t know what RTT
> you have at any time.
The endpoints can measure the RTT. Yes, it's probably a bit noisy and
there are several practical problems such as congestion on the reverse
path and multiple bottlenecks, but in general it's not impossible.
> Lola si not solving that. No protocol could BTW.
LoLa is exactly solving that. It measures RTTmin and effective RTT
(and there are lots of other delay-based CC proposals doing that)
and tries to control the overall queuing delay, even achieving
RTT-independent flow rate fairness.
> BTW I don’t see any formal proof about queue occupancy in the paper.
It's not in the LoLa paper, it was in a different paper, but reviewers
thought it was already common knowledge.
Regards,
Roland
> On Tue 27 Nov 2018 at 12:53, Bless, Roland (TM) <roland.bless@kit.edu
> <mailto:roland.bless@kit.edu>> wrote:
>
> Hi Luca,
>
> Am 27.11.18 um 12:01 schrieb Luca Muscariello:
> > A BDP is not a large buffer. I'm not unveiling a secret.
>
> That depends on speed and RTT (note that typically there are
> several flows with different RTTs sharing the same buffer).
> The essential point is not how much buffer capacity is available,
> but how much is actually used, because that adds queueing delay.
>
> > And it is just a rule of thumb to have an idea at which working point
> > the protocol is working.
>
> No, one can actually prove that this is the best size for
> loss-based CC with backoff factor of 0.5 (assuming a single flow).
>
> > In practice the protocol is usually working below or above that value.
>
> That depends on the protocol.
>
> > This is where AQM and ECN help also. So most of the time the
> protocol is
> > working at way
> > below 100% efficiency.
>
> > My point was that FQ_codel helps to get very close to the optimum w/o
> > adding useless queueing and latency.
> > With a single queue that's almost impossible. No, sorry. Just
> impossible.
>
> No, it's possible. Please read the TCP LoLa paper.
>
> Regards,
> Roland
>
next prev parent reply other threads:[~2018-11-27 12:22 UTC|newest]
Thread overview: 102+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-26 19:08 Pete Heist
2018-11-26 19:28 ` Neal Cardwell
2018-11-27 20:42 ` Dave Taht
2018-11-27 20:54 ` Toke Høiland-Jørgensen
2018-11-27 21:00 ` Dave Taht
2018-11-27 21:05 ` Toke Høiland-Jørgensen
2018-11-26 21:29 ` Jonathan Morton
2018-11-27 9:24 ` Luca Muscariello
2018-11-27 10:26 ` Bless, Roland (TM)
2018-11-27 10:29 ` Luca Muscariello
2018-11-27 10:35 ` Bless, Roland (TM)
2018-11-27 10:40 ` Luca Muscariello
2018-11-27 10:50 ` Mikael Abrahamsson
2018-11-27 11:01 ` Luca Muscariello
2018-11-27 11:21 ` Mikael Abrahamsson
2018-11-27 12:17 ` Jonathan Morton
2018-11-27 13:37 ` Luca Muscariello
2018-11-27 13:49 ` Mikael Abrahamsson
2018-11-27 14:07 ` Luca Muscariello
2018-11-27 14:18 ` Mikael Abrahamsson
2018-11-27 18:44 ` Kathleen Nichols
2018-11-27 19:25 ` Dave Taht
2018-11-27 21:57 ` Roland Bless
2018-11-27 11:53 ` Bless, Roland (TM)
2018-11-27 11:58 ` Luca Muscariello
2018-11-27 12:22 ` Bless, Roland (TM) [this message]
2018-11-27 11:06 ` Jonathan Morton
2018-11-27 11:07 ` Michael Welzl
2018-11-29 7:35 ` Dave Taht
2018-11-29 18:43 ` Stephen Hemminger
2018-11-29 19:08 ` Dave Taht
2018-11-30 5:51 ` Mikael Abrahamsson
2018-11-30 19:02 ` Dave Taht
2018-11-30 19:58 ` Stephen Hemminger
2018-11-27 11:04 ` Michael Welzl
2018-11-27 12:48 ` Bless, Roland (TM)
2018-11-27 11:40 ` Bless, Roland (TM)
2018-11-27 11:43 ` Bless, Roland (TM)
2018-11-29 7:39 ` Dave Taht
2018-11-29 7:45 ` Jonathan Morton
2018-11-29 7:54 ` Dave Taht
2018-11-29 8:09 ` Luca Muscariello
2018-11-29 13:49 ` Bless, Roland (TM)
2018-11-29 8:41 ` Bless, Roland (TM)
2018-11-29 7:33 ` Dave Taht
2018-11-29 8:13 ` Bless, Roland (TM)
2018-11-29 10:00 ` Pete Heist
2018-11-29 16:09 ` Luca Muscariello
2018-11-29 17:07 ` Mario Hock
2018-11-29 22:30 ` Luca Muscariello
2018-11-30 9:55 ` Mario Hock
2018-11-30 10:32 ` Luca Muscariello
2018-11-30 11:04 ` Jonathan Morton
2018-11-30 11:53 ` jf
2018-12-03 9:42 ` Mario Hock
2018-11-27 11:52 ` Toke Høiland-Jørgensen
2018-11-28 3:37 ` [Bloat] AFD Dave Taht
2018-11-27 20:58 ` [Bloat] when does the CoDel part of fq_codel help in the real world? Dave Taht
2018-11-27 22:19 ` Luca Muscariello
2018-11-27 22:30 ` Roland Bless
2018-11-27 23:17 ` Dave Taht
2018-11-28 3:47 ` Kathleen Nichols
2018-11-28 9:56 ` Luca Muscariello
2018-11-28 10:40 ` Dave Taht
2018-11-28 10:48 ` Luca Muscariello
2018-11-28 12:10 ` Bless, Roland (TM)
2018-11-29 7:22 ` Dave Taht
2018-11-29 7:20 ` Dave Taht
2018-11-27 20:50 ` Dave Taht
2018-11-26 21:56 ` Michael Welzl
2018-11-26 22:13 ` Toke Høiland-Jørgensen
2018-11-27 8:54 ` Pete Heist
2018-11-27 9:31 ` Jonathan Morton
2018-11-27 13:19 ` Michael Richardson
2018-11-27 18:59 ` Jonathan Morton
2018-11-27 20:10 ` Dave Taht
2018-11-27 21:17 ` Michael Welzl
2018-11-27 21:20 ` Michael Welzl
2018-11-29 7:11 ` Dave Taht
2018-11-29 7:28 ` [Bloat] incremental deployment, transport and L4S (Re: when does the CoDel part of fq_codel help in the real world?) Mikael Abrahamsson
2018-11-29 7:36 ` Jonathan Morton
2018-11-29 7:46 ` Mikael Abrahamsson
2018-11-29 8:08 ` Michael Welzl
2018-11-29 10:30 ` Jonathan Morton
2018-11-29 12:06 ` Michael Welzl
2018-11-29 12:52 ` Jonathan Morton
2018-11-30 7:54 ` Michael Welzl
2019-02-03 18:20 ` Dave Taht
2018-11-29 12:12 ` Michael Welzl
2018-11-29 12:56 ` Jonathan Morton
2018-11-29 13:30 ` Mikael Abrahamsson
2018-11-29 23:27 ` Jonathan Morton
2018-11-30 6:01 ` Mikael Abrahamsson
2018-11-29 14:06 ` Bless, Roland (TM)
2018-11-29 8:09 ` Jonathan Morton
2018-11-29 8:19 ` Mikael Abrahamsson
2018-11-29 8:34 ` Jonathan Morton
2018-11-29 10:15 ` Sebastian Moeller
2018-11-29 10:53 ` Mikael Abrahamsson
2018-11-30 4:54 ` Dave Taht
2018-11-28 2:04 ` [Bloat] when does the CoDel part of fq_codel help in the real world? Pete Heist
2018-11-28 3:52 ` Dave Taht
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