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From: Jonathan Morton <chromatix99@gmail.com>
To: Eric Dumazet <eric.dumazet@gmail.com>
Cc: make-wifi-fast@lists.bufferbloat.net,
	"codel@lists.bufferbloat.net" <codel@lists.bufferbloat.net>,
	Dave Taht <dave.taht@gmail.com>,
	ath10k <ath10k@lists.infradead.org>
Subject: Re: [Codel] fq_codel_drop vs a udp flood
Date: Sun, 1 May 2016 21:20:10 +0300	[thread overview]
Message-ID: <865DA393-262D-40B6-A9D3-1B978CD5F6C6@gmail.com> (raw)
In-Reply-To: <1462125592.5535.194.camel@edumazet-glaptop3.roam.corp.google.com>


> On 1 May, 2016, at 20:59, Eric Dumazet <eric.dumazet@gmail.com> wrote:
> 
> fq_codel_drop() could drop _all_ packets of the fat flow, instead of a
> single one.

Unfortunately, that could have bad consequences if the “fat flow” happens to be a TCP in slow-start on a long-RTT path.  Such a flow is responsive, but on an order-magnitude longer timescale than may have been configured as optimum.

The real problem is that fq_codel_drop() performs the same (excessive) amount of work to cope with a single unresponsive flow as it would for a true DDoS.  Optimising the search function is sufficient.

 - Jonathan Morton


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  reply	other threads:[~2016-05-01 18:20 UTC|newest]

Thread overview: 108+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-05-01  3:41 fq_codel_drop vs a udp flood Dave Taht
2016-05-01  4:46 ` [Make-wifi-fast] " Jonathan Morton
2016-05-01  5:08 ` Ben Greear
2016-05-01  5:23   ` Dave Taht
2016-05-01 14:47     ` [Make-wifi-fast] " dpreed
2016-05-02 14:03       ` Roman Yeryomin
2016-05-02 18:40         ` Dave Taht
2016-05-05 13:55           ` Roman Yeryomin
2016-05-05 14:55             ` Roman Yeryomin
2016-05-02 19:47         ` David Lang
2016-05-01 17:59 ` [Codel] " Eric Dumazet
2016-05-01 18:20   ` Jonathan Morton [this message]
2016-05-01 18:46     ` Eric Dumazet
2016-05-01 19:55       ` Eric Dumazet
2016-05-02  7:47         ` Jesper Dangaard Brouer
2016-05-01 20:35       ` Jonathan Morton
2016-05-01 20:55         ` Eric Dumazet
2016-05-02 14:18           ` Roman Yeryomin
2016-05-02 15:07             ` Eric Dumazet
2016-05-02 15:43               ` Roman Yeryomin
2016-05-02 16:14                 ` Eric Dumazet
2016-05-02 17:08                   ` Dave Taht
2016-05-02 17:44                     ` Eric Dumazet
2016-05-05 14:32                     ` Roman Yeryomin
2016-05-05 14:53                   ` Roman Yeryomin
2016-05-05 15:32                     ` Dave Taht
2016-05-05 16:07                       ` Roman Yeryomin
2016-05-05 16:59                         ` Jonathan Morton
2016-05-05 17:39                           ` Roman Yeryomin
2016-05-05 18:16                             ` Dave Taht
2016-05-05 18:33                           ` Dave Taht
2016-05-05 16:12                     ` Eric Dumazet
2016-05-05 16:25                       ` Roman Yeryomin
2016-05-05 16:42                         ` Roman Yeryomin
2016-05-06 10:55                           ` Roman Yeryomin
2016-05-05 19:23                         ` Eric Dumazet
2016-05-05 19:41                           ` Dave Taht
2016-05-06  8:41                             ` moeller0
2016-05-06 11:33                               ` Jesper Dangaard Brouer
2016-05-06 11:46                                 ` moeller0
2016-05-06 13:25                                   ` Eric Dumazet
2016-05-06 15:25                                     ` moeller0
2016-05-06 15:58                                       ` Eric Dumazet
2016-05-06 16:30                                         ` moeller0
2016-05-06 15:55                                     ` [PATCH net-next] fq_codel: add memory limitation per queue Eric Dumazet
2016-05-09  3:49                                       ` David Miller
2016-05-09  4:14                                       ` Cong Wang
2016-05-09  4:31                                         ` Eric Dumazet
2016-05-09  5:07                                           ` Cong Wang
2016-05-09 14:26                                             ` Eric Dumazet
2016-05-10  4:34                                               ` Cong Wang
2016-05-10  4:45                                                 ` Eric Dumazet
2016-05-10  4:57                                                   ` Cong Wang
2016-05-10  5:10                                                     ` Eric Dumazet
2016-05-16  1:16                                       ` [PATCH net-next] fq_codel: fix memory limitation drift Eric Dumazet
2016-05-17  1:57                                         ` David Miller
2016-05-06  9:42                           ` OpenWRT wrong adjustment of fq_codel defaults (Was: fq_codel_drop vs a udp flood) Jesper Dangaard Brouer
2016-05-06  9:42                             ` OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " Jesper Dangaard Brouer
2016-05-06 12:47                             ` OpenWRT wrong adjustment of fq_codel defaults (Was: " Jesper Dangaard Brouer
2016-05-06 12:47                               ` OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " Jesper Dangaard Brouer
2016-05-06 18:43                               ` OpenWRT wrong adjustment of fq_codel defaults (Was: " Roman Yeryomin
2016-05-06 18:43                                 ` OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " Roman Yeryomin
2016-05-06 18:56                                 ` OpenWRT wrong adjustment of fq_codel defaults (Was: " Roman Yeryomin
2016-05-06 18:56                                   ` OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " Roman Yeryomin
2016-05-06 19:43                                   ` OpenWRT wrong adjustment of fq_codel defaults (Was: " Dave Taht
2016-05-06 19:43                                     ` OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " Dave Taht
2016-05-15 22:34                                     ` OpenWRT wrong adjustment of fq_codel defaults (Was: " Roman Yeryomin
2016-05-15 22:34                                       ` OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " Roman Yeryomin
2016-05-15 23:07                                       ` OpenWRT wrong adjustment of fq_codel defaults (Was: " Eric Dumazet
2016-05-15 23:07                                         ` OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " Eric Dumazet
2016-05-15 23:27                                         ` OpenWRT wrong adjustment of fq_codel defaults (Was: " Roman Yeryomin
2016-05-15 23:27                                           ` OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " Roman Yeryomin
2016-05-16  8:12                                       ` [Make-wifi-fast] OpenWRT wrong adjustment of fq_codel defaults (Was: " David Lang
2016-05-16  8:12                                         ` [Make-wifi-fast] OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " David Lang
2016-05-16  8:26                                         ` Roman Yeryomin
2016-05-16  8:26                                           ` Roman Yeryomin
2016-05-16  8:46                                           ` [Make-wifi-fast] OpenWRT wrong adjustment of fq_codel defaults (Was: " David Lang
2016-05-16  8:46                                             ` [Make-wifi-fast] OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " David Lang
2016-05-16 10:34                                             ` [OpenWrt-Devel] [Make-wifi-fast] OpenWRT wrong adjustment of fq_codel defaults (Was: " Sebastian Moeller
2016-05-16 10:34                                               ` [OpenWrt-Devel] [Make-wifi-fast] OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " Sebastian Moeller
2016-05-16  8:14                                       ` OpenWRT wrong adjustment of fq_codel defaults (Was: " Roman Yeryomin
2016-05-16  8:14                                         ` OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " Roman Yeryomin
2016-05-16 14:23                                         ` [Make-wifi-fast] OpenWRT wrong adjustment of fq_codel defaults (Was: " Eric Dumazet
2016-05-16 14:23                                           ` [Make-wifi-fast] OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " Eric Dumazet
2016-05-16 16:04                                         ` Dave Taht
2016-05-16 16:04                                           ` Dave Taht
2016-05-16 19:46                                           ` OpenWRT wrong adjustment of fq_codel defaults (Was: " Roman Yeryomin
2016-05-16 19:46                                             ` OpenWRT wrong adjustment of fq_codel defaults (Was: [Codel] " Roman Yeryomin
2016-05-07  9:57                             ` Kevin Darbyshire-Bryant
2016-05-15 22:47                               ` Roman Yeryomin
2016-05-15 22:47                                 ` Roman Yeryomin
2016-05-03  2:26     ` [Codel] fq_codel_drop vs a udp flood Dave Taht
2016-05-03  5:21       ` Dave Taht
2016-05-03 12:39         ` Agarwal, Anil
2016-05-03 12:50           ` Agarwal, Anil
2016-05-03 13:35             ` Eric Dumazet
2016-05-03 15:37               ` Agarwal, Anil
2016-05-03 17:37               ` Dave Taht
2016-05-03 17:54                 ` Eric Dumazet
2016-05-03 18:11                   ` Dave Taht
2016-05-03 13:20       ` Kevin Darbyshire-Bryant
2016-05-01 18:26   ` Dave Taht
2016-05-01 22:30     ` Eric Dumazet
2016-05-02 14:09   ` Roman Yeryomin
2016-05-02 15:04     ` Eric Dumazet
2016-05-02 15:42       ` Roman Yeryomin
2016-05-02 13:47 ` [Make-wifi-fast] " Roman Yeryomin
2016-05-02 15:01   ` Eric Dumazet

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