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From: Pavel Machek <pavel@ucw.cz>
To: Andreas Petlund <apetlund@simula.no>
Cc: "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
	Ilpo J?rvinen <ilpo.jarvinen@helsinki.fi>,
	Eric Dumazet <eric.dumazet@gmail.com>,
	Arnd Hannemann <hannemann@nets.rwth-aachen.de>,
	LKML <linux-kernel@vger.kernel.org>,
	shemminger@vyatta.com, David Miller <davem@davemloft.net>,
	william.allen.simpson@gmail.com, damian@tvk.rwth-aachen.de,
	"Eric W. Biederman" <ebiederm@xmission.com>
Subject: Re: [net-next PATCH v4 1/3] net: TCP thin-stream detection
Date: Sun, 21 Feb 2010 11:21:03 +0100	[thread overview]
Message-ID: <20100221102102.GB1311@ucw.cz> (raw)
In-Reply-To: <4B7AAE60.3070305@simula.no>

Hi!

> +After analysing a large number of time-dependent interactive
> +applications, we have seen that they often produce thin streams
> +and also stay with this traffic pattern throughout its entire
> +lifespan. The combination of time-dependency and the fact that the
> +streams provoke high latencies when using TCP is unfortunate.
> +
> +In order to reduce application-layer latency when packets are lost,
> +a set of mechanisms has been made, which address these latency issues
> +for thin streams. In short, if the kernel detects a thin stream,
> +the retransmission mechanisms are modified in the following manner:
> +
> +1) If the stream is thin, fast retransmit on the first dupACK.
> +2) If the stream is thin, do not apply exponential backoff.

2) seems very dangerous/unfair. If network  congestion is caused just
by thin streams, will the network just fall apart?


-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

  parent reply	other threads:[~2010-02-21 10:21 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-02-16 14:40 Andreas Petlund
2010-02-18  0:32 ` David Miller
2010-02-21 10:21 ` Pavel Machek [this message]
2010-02-21 11:23   ` Alexander Zimmermann
2010-02-21 20:04     ` Lars Eggert
2010-02-21 23:03       ` David Miller
2010-02-22  6:41         ` Lars Eggert
2010-02-22 15:17           ` Andi Kleen
2010-02-22 15:35             ` Alexander Zimmermann
2010-02-22 15:40             ` Andreas Petlund
2010-02-22 15:51             ` Andreas Petlund
2010-02-22 16:06             ` Hagen Paul Pfeifer
2010-02-22 22:13             ` David Miller
2010-02-21 22:36     ` Ilpo Järvinen
2010-02-21 22:18   ` Hagen Paul Pfeifer
2010-02-21 22:31   ` Ilpo Järvinen

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