From: Daniel Roesen <dr@cluenet.de>
To: linux-kernel@vger.kernel.org
Subject: Re: 2.6.0 NFS-server low to 0 performance
Date: Wed, 14 Jan 2004 04:00:00 +0100 [thread overview]
Message-ID: <20040114040000.A27701@homebase.cluenet.de> (raw)
In-Reply-To: <20040113003908.GB4752@elf.ucw.cz>; from pavel@suse.cz on Tue, Jan 13, 2004 at 01:39:08AM +0100
On Tue, Jan 13, 2004 at 01:39:08AM +0100, Pavel Machek wrote:
> > Hm, as long as we are already on this - can you give me a hint / pointer
> > how does TCP _detect_ a congestion? Does it adjust packet sizes, some
> > other parameters? Just for the curiousity sake.
>
> If TCP sees packets are lost, it says "oh, congestion", and starts
> sending packets more slowly ie introduces delays
> between packets. When they no longer get lost, it
> speeds up to full speed.
You missed the important part... TCP measures latency and adjusts to
that. TCP overreacts on sudden unexpected packetloss by shrinking window
down.
This is why traffic "policing" sucks for TCP, and "shaping" (queuing)
works much better (as latency rises when limit is reached, and TCP
sender adapts by sending slower, thus preventing packet loss).
Regards,
Daniel
next prev parent reply other threads:[~2004-01-14 3:00 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-01-06 0:46 Guennadi Liakhovetski
2004-01-07 13:36 ` Guennadi Liakhovetski
2004-01-07 22:30 ` bill davidsen
2004-01-08 12:48 ` Guennadi Liakhovetski
2004-01-07 17:49 ` Mike Fedyk
2004-01-07 18:13 ` Guennadi Liakhovetski
2004-01-07 18:19 ` Mike Fedyk
2004-01-07 19:06 ` Guennadi Liakhovetski
2004-01-09 10:08 ` Guennadi Liakhovetski
2004-01-09 18:00 ` Mike Fedyk
2004-01-10 0:38 ` Guennadi Liakhovetski
2004-01-10 1:38 ` Mike Fedyk
2004-01-10 11:10 ` Guennadi Liakhovetski
2004-01-10 14:30 ` Trond Myklebust
2004-01-10 20:04 ` Guennadi Liakhovetski
2004-01-10 21:57 ` Trond Myklebust
2004-01-10 22:14 ` Mike Fedyk
2004-01-10 22:47 ` Trond Myklebust
2004-01-10 22:42 ` Guennadi Liakhovetski
2004-01-10 22:51 ` Jesper Juhl
2004-01-11 13:18 ` Helge Hafting
2004-01-11 13:53 ` Russell King
2004-01-11 14:24 ` Guennadi Liakhovetski
2004-01-15 11:38 ` Pavel Machek
2004-01-12 5:06 ` Bill Davidsen
2004-01-12 14:27 ` Trond Myklebust
2004-01-12 15:12 ` Trond Myklebust
2004-01-16 5:44 ` Mike Fedyk
2004-01-16 6:05 ` Trond Myklebust
2004-01-16 6:53 ` Mike Fedyk
2004-01-10 22:34 ` Mike Fedyk
2004-01-10 22:52 ` Guennadi Liakhovetski
2004-01-10 22:57 ` Mike Fedyk
2004-01-10 23:00 ` Guennadi Liakhovetski
2004-01-08 21:42 ` Pavel Machek
2004-01-12 23:18 ` Guennadi Liakhovetski
2004-01-12 23:28 ` Jesper Juhl
2004-01-13 0:39 ` Pavel Machek
2004-01-14 3:00 ` Daniel Roesen [this message]
2004-01-14 18:16 ` Guennadi Liakhovetski
2004-01-13 1:55 ` Slow NFS performance over wireless! Roman Gaufman
2004-01-13 2:15 ` Trond Myklebust
2004-01-13 20:25 ` Joshua M. Thompson
2004-01-13 20:45 ` Trond Myklebust
2004-01-15 1:12 ` Miquel van Smoorenburg
[not found] ` <20040115013312.GO1594@srv-lnx2600.matchmail.com>
2004-01-15 2:04 ` Miquel van Smoorenburg
2004-01-15 2:35 ` Trond Myklebust
2004-01-15 19:00 ` Slowwwwwwwwwwww NFS read performance Trond Myklebust
2004-01-15 19:53 ` Ram Pai
2004-01-15 20:16 ` Trond Myklebust
2004-01-15 20:54 ` Trond Myklebust
2004-01-18 6:04 ` Greg Fitzgerald
2004-01-18 17:55 ` Mike Fedyk
2004-01-16 0:52 ` Slow NFS performance [was: over wireless!] Miquel van Smoorenburg
[not found] <1cpDr-5az-11@gated-at.bofh.it>
[not found] ` <1csrv-Er-9@gated-at.bofh.it>
2004-01-10 16:08 ` 2.6.0 NFS-server low to 0 performance Andi Kleen
2004-01-10 16:19 ` Trond Myklebust
2004-01-12 14:40 James Pearson
2004-01-12 15:22 ` Trond Myklebust
2004-01-13 11:08 ` Muli Ben-Yehuda
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