Markus Adolfsson wrote:
My name is Markus Adolfsson and I'm a 25 year old master student at
University of Halmstad in Sweden. We are currently developing end nodes
in Linux that must be able to generate and receive Ethernet frames with
as little interference as possible from existing protocols.
We know how to solve the problem in user space by developing some sort
of deamon that uses PF_SOCKET and delivers incoming traffic matching a
certain pattern to our end node application. However, our master thesis
project's keyword is determinism and a latency > 5 ms is not acceptable.
You cannot guarantee low latency just by putting stuff in the kernel,
though that may help your average case. You may get better luck by
using scheduling tricks to make your program run at a high priority.
You could even use some of the many near-realtime patches for linux.
What speeds are you looking to achieve?
Ben
Since the only way out of this requires a kernel space implementation,
we need to build our own protocol handler that receives and handles our
traffic. I've studied a couple of your articles at www.linuxjournal.com
but would really appreciate your guidance.
I'd like to be able to do a "Other Layer 3 Protocol Handler" as seen in
www.linuxjournal.com/modules/NS-lj-issues/issue95/5617f1.png but I find
it quite difficult to understand all of the source code in similar
handlers such as /net/ipv4. Which files should I look into and what are
the essential functions that I would have to redefine? The files are
quite big and some sort of map would really be nice, indicating which
function that calls ip_init() in net/ipv4/ip_output.c? Where would I
need to register my "own" protocol handler? I'm an experienced
programmer but I have never been hacking in the Linux kernel before...
.I realize that this probably is a quite big question that probably need
a rather big answer but I'm starting to get a little bit desperate and
any help of yours is highly appreciated;)
-- Best regards, Markus Adolfsson
--
Ben Greear <greearb@xxxxxxxxxxxxxxx> <Ben_Greear AT excite.com>
President of Candela Technologies Inc http://www.candelatech.com
ScryMUD: http://scry.wanfear.com http://scry.wanfear.com/~greear
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