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Re: [tcpm] Ordering of SACK blocks, flushing of reassembly queue after inactivity

David Malone <David.Malone@nuim.ie> Thu, 24 January 2008 15:24 UTC

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To: Lars Eggert <lars.eggert@nokia.com>
Subject: Re: [tcpm] Ordering of SACK blocks, flushing of reassembly queue after inactivity
In-Reply-To: Your message of "Thu, 24 Jan 2008 17:04:25 +0200." <1648983D-9F94-4C59-88AD-78496CBFA119@nokia.com>
From: David Malone <David.Malone@nuim.ie>
Date: Thu, 24 Jan 2008 15:24:29 +0000
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> The highspeed TCP folks have reported cases where SACK processing can  
> eat CPU cycles up to a degree where it significantly affects  
> performance. (I think this was under Linux.) I'm not sure if this is  
> an issue with the code or an issue with the spec; if it's the latter,  
> we may have some work to do. (But you probably know more about this  
> than I do anyway.)

I think it was mainly implementation issues, see Chapter 3 of:

	http://www.hamilton.ie/publications/baruch_even_thesis.pdf

it describes how to fix some of the problems. With that, there were
no problems running up to about 1Gbps with sizeable RTTs.

	David.


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