netdev - Re: TCP window auto-tuning sub-optimal in GRE tunnel

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Message-ID: <1432593501.4060.193.camel@edumazet-glaptop2.roam.corp.google.com>
Date:	Mon, 25 May 2015 15:38:21 -0700
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	"John A. Sullivan III" <jsullivan@...nsourcedevel.com>
Cc:	netdev@...r.kernel.org
Subject: Re: TCP window auto-tuning sub-optimal in GRE tunnel

On Mon, 2015-05-25 at 18:22 -0400, John A. Sullivan III wrote:

> 2) Why do we still not negotiate the 16MB buffer that we get when we are
> not using GRE?

What exact NIC handles receive side ?

If drivers allocate a full 4KB page to hold each frame,
plus sk_buff overhead,
then 32MB of kernel memory translates to 8MB of TCP window space.

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