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From: Jonathan Morton <chromatix99@gmail.com>
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To: Stephen Hemminger <stephen@networkplumber.org>
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Subject: Re: [Cake] the meta problem of memory, locks, and multiple cpus
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> On 3 Nov, 2015, at 02:55, Stephen Hemminger =
<stephen@networkplumber.org> wrote:
>=20
> Why not measure the egress rate like PIE?

Because there is often quite a lot of buffering in the device and/or =
driver which can easily mask the true link rate, by absorbing bursts of =
traffic at extremely high rates.  This is a greater problem in ordinary =
Ethernet NICs than in cable modems.  It is likewise (and more obviously) =
a problem when a fast Ethernet link exists between the router and a slow =
last-mile modem.

> Also many devices (like wifi) can't report real link rate.

On the contrary, Minstrel knows what rate it has (momentarily) selected =
for the wifi device to use (though it is then diluted by contention for =
the medium).  Exposing that to other layers of the network stack is the =
challenge.

 - Jonathan Morton