From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: TCP and reordering
Date: Wed, 28 Nov 2012 09:16:36 -0800
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Cc: Benjamin LaHaise <bcrl@kvack.org>,
	Vijay Subramanian <subramanian.vijay@gmail.com>,
	David Miller <davem@davemloft.net>, saku@ytti.fi,
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To: David Woodhouse <dwmw2@infradead.org>
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On Wed, 2012-11-28 at 16:41 +0000, David Woodhouse wrote:

> Another fun issue with tunnelling protocols and BQL... packets tend to
> *grow* as they get encapsulated. So you might end up calling
> netdev_sent_queue() with a given size, then netdev_completed_queue()
> with a bigger packet later...

Its the driver responsibility to maintain the coherent 'bytes' value for
each transmitted/completed packet.

If a driver calls an external entity, it cannot possibly use BQL, unless
doing an approximation (bytes becomes a fixed value)

BQL was really something to control/limit queueing on ethernet links,
not for stacked devices, as stacked devices normally have no queue.