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From: David Miller <davem@davemloft.net>
To: dada1@cosmosbay.com
Cc: nuclearcat@nuclearcat.com, linux-kernel@vger.kernel.org,
	netdev@vger.kernel.org
Subject: Re: 2.6.21 -> 2.6.22 & 2.6.23-rc8 performance regression
Date: Mon, 01 Oct 2007 13:57:10 -0700 (PDT)	[thread overview]
Message-ID: <20071001.135710.99174896.davem@davemloft.net> (raw)
In-Reply-To: <4701541B.70108@cosmosbay.com>

From: Eric Dumazet <dada1@cosmosbay.com>
Date: Mon, 01 Oct 2007 22:10:03 +0200

> So maybe the following patch is necessary...
> 
> I believe IPV6 & DCCP are immune to this problem.
> 
> Thanks again Denys for spotting this.
> 
> Eric
> 
> [PATCH] TCP : secure_tcp_sequence_number() should not use a too fast clock
> 
> TCP V4 sequence numbers are 32bits, and RFC 793 assumed a 250 KHz clock.
> In order to follow network speed increase, we can use a faster clock, but
> we should limit this clock so that the delay between two rollovers is
> greater than MSL (TCP Maximum Segment Lifetime : 2 minutes)
> 
> Choosing a 64 nsec clock should be OK, since the rollovers occur every
> 274 seconds.
> 
> Problem spotted by Denys Fedoryshchenko
> 
> Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>

Thanks a lot Eric for bringing closure to this.

I'll apply this and add a reference in the commit message to the
changeset that introduced this problem, since it might help
others who look at this.

      reply	other threads:[~2007-10-01 20:57 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20070930144443.M52139@visp.net.lb>
     [not found] ` <46FFE17C.9020202@cosmosbay.com>
     [not found]   ` <200709301425.37564.nickpiggin@yahoo.com.au>
     [not found]     ` <20070930223503.M8966@nuclearcat.com>
2007-10-01  5:59       ` 2.6.21 -> 2.6.22 & 2.6.23-rc8 performance regression Eric Dumazet
2007-10-01  7:12         ` David Miller
2007-10-01  8:07           ` Denys
2007-10-01  8:20             ` Eric Dumazet
2007-10-01  8:35               ` Eric Dumazet
2007-10-01 12:10               ` Denys
2007-10-01 13:26               ` Denys
2007-10-01 20:10         ` Eric Dumazet
2007-10-01 20:57           ` David Miller [this message]

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