Date: Fri, 10 Jan 2003 19:35:01 +0100
Message-Id: <200301101835.h0AIZ1B04255@mail.intergenia.de>
To: <200301101645.39535.dark_lkml@mymail.ro>
From: Gianni Tedesco <gianni@ecsc.co.uk>
Subject: Re: Kernel hooks just to get rid of copy_[to/from]_user() and [rescued]
CC: linux-kernel@vger.kernel.org
Sender: linux-kernel-owner@vger.kernel.org
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On Fri, 2003-01-10 at 14:45, Mihnea Balta wrote:
> Hi,
>=20
> I have to implement a system which grabs udp packets off a gigabit connec=
tion,=20
> take some basic action based on what they contain, repack their data with=
 a=20
> custom protocol header and send them through a gigabit ethernet interface=
 on=20
> broadcast.
>=20
> I know how to do this in userspace, but I need to know if doing everyting=
 in=20
> the kernel would show a considerable speed improvement due to removing=20
> syscall and memory copy overhead. The system will be quite stressed, havi=
ng=20
> to deal with around 15-20000 packets/second.

mmap() packet socket interface eliminates the need for system calls when
traffic is coming in at a high rate.  The kernel -> user copy is also
eliminated, but its just replaced with a kernel -> kernel copy :P

You could perhaps also use linux socket filters to minimize the number
of packets you need to evaluate...

Check out this sample code: http://www.scaramanga.co.uk/code-fu/lincap.c

HTH

--=20
// Gianni Tedesco (gianni at scaramanga dot co dot uk)
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