netdev - Re: TCP rx window autotuning harmful at LAN context

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Message-ID: <20090311150149.GG11935@one.firstfloor.org>
Date:	Wed, 11 Mar 2009 16:01:49 +0100
From:	Andi Kleen <andi@...stfloor.org>
To:	David Miller <davem@...emloft.net>
Cc:	andi@...stfloor.org, md@....sk, netdev@...r.kernel.org
Subject: Re: TCP rx window autotuning harmful at LAN context

On Wed, Mar 11, 2009 at 06:30:58AM -0700, David Miller wrote:
> From: Andi Kleen <andi@...stfloor.org>
> Date: Wed, 11 Mar 2009 11:03:35 +0100
> 
> > Perhaps this points to the default buffer sizing heuristics to 
> > be too aggressive for >= 1GB?
> 
> It's necessary Andi, you can't fill a connection on a trans-
> continental connection without at least a 4MB receive buffer.

Seems pretty arbitary to me. It's the value for a given bandwidth*latency
product, but why not half or twice the bandwidth? I don't think
that number is written in stone like you claim.

Anyways it was just a test patch and it indeeds seems to address
the problem at least partly.

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only.
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