David S. Miller wrote:
From: John Ronciak <[EMAIL PROTECTED]>
Date: Wed, 7 Dec 2005 11:48:46 -0800
Copybreak probably shouldn't be used in routing use cases.
I think even this is arguable, routers route a lot more than
small 64-byte frames. Unfortunately, that is what everyone
uses for packet rate tests. :-/
Assuming only TCP flows go through a router, it is safe to
say that the full-sized data frame to ACK ratio is about 2
to 1.
Sadly, the picture most routers see is the opposite: about 2 sub-100
byte frames for every 1 decent sized one - and fullsize is really rare,
maybe just 1 in 5.
This thread is semi-modern with some good data:
http://www.cctec.com/maillists/nanog/historical/0312/msg00394.html
and it is getting worse over time.. in 1998 it was more like 1:1
So the all-64byte test isn't that crazy.
BTW - this has been a great thread - enjoyed reading it very much. But
I've kind of lost a feel for what the prefetch and copybreak cases mean
for local delievery (e.g tcp termination) scenarios.. both in throughput
and cpu left for the local application. That has to be a more important
profile than ip forwarding. Any thoughts on that?
-Patrick
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