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From: "Toke Høiland-Jørgensen" <toke@toke.dk>
To: Luca Muscariello <luca.muscariello@gmail.com>
Cc: Y <intruder_tkyf@yahoo.fr>, Cake List <cake@lists.bufferbloat.net>
Subject: Re: [Cake] A few puzzling Cake results
Date: Tue, 17 Apr 2018 17:10:44 +0200	[thread overview]
Message-ID: <87sh7t3m2z.fsf@toke.dk> (raw)
In-Reply-To: <CAHx=1M6R=2LzNb+TbKfq-czptoFUf6yHPWp0435s23NnAov4YQ@mail.gmail.com>

Luca Muscariello <luca.muscariello@gmail.com> writes:

> I will check that later, still unsure.
>
> First guess: the quantum component should influence only how close to a
> fluid bit-wise approximation you are.
> So cake gets closer by automatic adjustment.
>
> The computation of the correction factor should be done by computing the
> probability that a packet
> of a sparse flow loses priority because of the quantum. Bad setting, higher
> probability, ideal setting 0 probability.
>
> So your formula seems still wrong to me...

The formula expresses the conditions under which a flow is guaranteed to
be treated as sparse by the scheduler, under some quite strong
assumptions (most notably that the sparse flow is sending packets at a
fixed rate).

It's derived from the fact that when a packet from the sparse flow
arrives, it (in the worst case) has to wait for the bulk flow packet
that just started getting service (i.e., wait for L/R), after which the
sparse flow itself will get service (in time L_s/R), then it will have
to wait for its queue to pass through a whole round of scheduling (LN/R)
before it can get service as a sparse flow again. Adding these together,
the inter-arrival time between sparse flow packets has to be greater
then (L(N+1)+L_s)/R, which when converted to a rate gives the formula I
mentioned.

You are right, of course, that in the general case it will be different;
but I was talking about the specific case of the fixed-rate sparse flow
here... :)

-Toke

  reply	other threads:[~2018-04-17 15:10 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-17  9:42 Toke Høiland-Jørgensen
2018-04-17 10:04 ` Luca Muscariello
2018-04-17 10:38   ` Toke Høiland-Jørgensen
2018-04-17 12:05     ` Y
     [not found]     ` <mailman.225.1523966725.3573.cake@lists.bufferbloat.net>
2018-04-17 12:22       ` Toke Høiland-Jørgensen
2018-04-17 13:16         ` Jonas Mårtensson
2018-04-17 13:50           ` Toke Høiland-Jørgensen
2018-04-17 13:47         ` Luca Muscariello
2018-04-17 13:52         ` Luca Muscariello
2018-04-17 14:25           ` Toke Høiland-Jørgensen
2018-04-17 14:54             ` Luca Muscariello
2018-04-17 15:10               ` Toke Høiland-Jørgensen [this message]
2018-04-17 14:03 ` Jonathan Morton
2018-04-17 14:17   ` Toke Høiland-Jørgensen
2018-04-18 11:25     ` Toke Høiland-Jørgensen
2018-04-18 12:21       ` Kevin Darbyshire-Bryant
2018-04-18 12:57         ` Toke Høiland-Jørgensen
2018-04-18 13:13       ` Jonas Mårtensson
2018-04-18 13:21         ` Toke Høiland-Jørgensen
2018-04-18 14:12       ` Jonathan Morton
2018-04-18 14:30         ` Toke Høiland-Jørgensen
2018-04-18 15:03           ` Jonathan Morton
2018-04-18 15:17             ` Sebastian Moeller
2018-04-18 15:58               ` Jonathan Morton
2018-04-18 16:11                 ` Toke Høiland-Jørgensen
2018-04-18 16:25                   ` Dave Taht
2018-04-18 16:34                     ` Georgios Amanakis
2018-04-18 17:10                       ` Sebastian Moeller
2018-04-19  7:49                     ` Luca Muscariello
2018-04-19  8:11                       ` Jonathan Morton
2018-04-19  9:00                         ` Toke Høiland-Jørgensen
2018-04-19  9:21                           ` Jonathan Morton
2018-04-19  9:26                             ` Toke Høiland-Jørgensen
2018-04-19  9:55                               ` Jonathan Morton
2018-04-19 10:33                                 ` Toke Høiland-Jørgensen
2018-04-19 11:55                                   ` Luca Muscariello
2018-04-18 16:54                   ` Jonathan Morton
2018-04-18 17:02                     ` Dave Taht
2018-04-18 18:06                       ` Jonas Mårtensson
2018-04-18 18:11                         ` Toke Høiland-Jørgensen
2018-04-18 18:16                           ` Kevin Darbyshire-Bryant
     [not found]                           ` <mailman.238.1524075384.3573.cake@lists.bufferbloat.net>
2018-04-19  8:31                             ` Kevin Darbyshire-Bryant
2018-04-18 18:11                     ` Jonas Mårtensson
2018-04-18 19:53                     ` David Lang
2018-04-18 21:53                       ` Jonathan Morton
2018-04-19  9:22                         ` Toke Høiland-Jørgensen
2018-04-19  9:32                           ` Jonathan Morton

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