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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
> 


  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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