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From: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
To: David Miller <davem@davemloft.net>
Cc: shemminger@osdl.org, alex@sectorb.msk.ru, netdev@vger.kernel.org
Subject: Re: high latency with TCP connections
Date: Fri, 1 Sep 2006 13:47:15 +0400	[thread overview]
Message-ID: <20060901094715.GB13855@ms2.inr.ac.ru> (raw)
In-Reply-To: <20060831.165701.104033558.davem@davemloft.net>

Hello!

> problem.  The problem is really at the receiver because we only
> ACK every other full sized frame.  I had the idea to ACK every 2
> frames, regardless of size,

This would solve lots of problems.


>			 but that might have other problems.

BSD used to do this, everyone is happy.

It could disclose some new problems in our stack, because we have
quite a lot of code to mitigate problems caused by ACK each 2*MSS.
But they should not be essential. Actually, we could have it adjustable:
normally each 2 frames, but apply efforts to coarsen ACKs up to 2*MSS,
when lots of small frames are ACKed back to back.


> There is an assymetry between how we do congestion control on
> sending (packet counting) and our ACK policy on receive (packet
> sized based).

It is curious fact: BSD has exactly opposite assymetry.
ACK are sent each second packet, but congestion avoidance is made by size. :-)


> turn it off by default.

Yes.

Alexey


  parent reply	other threads:[~2006-09-01  9:47 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-08-30 10:07 high latency with TCP connections Alexander Vodomerov
2006-08-30 17:27 ` Stephen Hemminger
2006-08-30 21:39   ` David Miller
2006-08-30 22:04     ` Stephen Hemminger
2006-08-30 23:00     ` Rick Jones
2006-08-31  8:14     ` Alexander Vodomerov
2006-08-31 15:44       ` Sridhar Samudrala
2006-08-31 18:22     ` Kelly Burkhart
2006-08-31 19:40       ` Rick Jones
2006-08-31 21:08       ` Ian McDonald
2006-08-31 21:46   ` Alexey Kuznetsov
2006-08-31 22:14     ` Stephen Hemminger
2006-08-31 22:44       ` David Miller
2006-08-31 23:29         ` Alexey Kuznetsov
2006-08-31 23:57           ` David Miller
2006-09-01  3:23             ` Stephen Hemminger
2006-09-01  3:39               ` Ian McDonald
2006-09-01  6:23                 ` David Miller
2006-09-01  9:44             ` Pekka Savola
2006-09-01  9:49               ` David Miller
2006-09-01  9:47             ` Alexey Kuznetsov [this message]
2006-09-01 11:00               ` Evgeniy Polyakov
     [not found]                 ` <20060901090046.69b3d583@localhost.localdomain>
2006-09-01 20:55                   ` [PATCH] tcp: turn ABC off Stephen Hemminger
2006-09-02  7:22                     ` Evgeniy Polyakov
2006-09-02  8:10                       ` Herbert Xu
2006-09-04  9:10                 ` high latency with TCP connections Alexey Kuznetsov
2006-09-04 16:00 ` [PATCH][RFC] " Alexey Kuznetsov
2006-09-05 17:55   ` Rick Jones
2006-09-05 22:13     ` Alexey Kuznetsov
2006-09-18  7:39     ` David Miller
2006-09-18 17:11       ` Rick Jones
2006-09-18 20:41         ` Alexey Kuznetsov
2006-09-18 21:24           ` Rick Jones
2006-09-18 22:51             ` Alexey Kuznetsov
2006-09-19  0:37               ` Rick Jones
2006-09-22 13:46                 ` Alexey Kuznetsov
2006-09-22 17:15                   ` Rick Jones
2006-09-18  7:31   ` David Miller
2006-09-18 10:37     ` Alexey Kuznetsov
2006-09-18 13:56       ` David Miller
2006-09-20 22:44         ` Stephen Hemminger
2006-09-20 22:47           ` David Miller
2006-09-20 22:55             ` Stephen Hemminger

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