Subject: Re: [PATCH] NET: Multiqueue network device support.

From: jamal <[email-masked]>
Date: Tue, 12 Jun 2007 08:17:42 -0400

On Tue, 2007-12-06 at 11:19 +0200, Johannes Berg wrote:
> On Mon, 2007-06-11 at 08:23 -0400, jamal wrote:

> > Sure. Packets stashed on the any DMA ring are considered "gone to the
> > wire". That is a very valid assumption to make.
> 
> Not at all! Packets could be on the DMA queue forever if you're feeding
> out more packets. Heck, on most wireless hardware packets can even be
> *expired* from the DMA queue and you get an indication that it was
> impossible to send them.

The spirit of the discussion you are quoting was much higher level than
that. Yes what you describe can happen on any DMA (to hard-disk etc)
A simpler example, if you tcpdump on an outgoing packet you see it on
its way to the driver - it is accounted for as "gone"[1].
In any case, read the rest of the thread.

cheers,
jamal

[1] Current Linux tcpdumping is not that accurate, but i dont wanna go
into that discussion