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SubjectRe: Kernel hooks just to get rid of copy_[to/from]_user() and syscall overhead?
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On Fri, 2003-01-10 at 14:45, Mihnea Balta wrote:
> Hi,
>
> I have to implement a system which grabs udp packets off a gigabit connection,
> take some basic action based on what they contain, repack their data with a
> custom protocol header and send them through a gigabit ethernet interface on
> broadcast.
>
> I know how to do this in userspace, but I need to know if doing everyting in
> the kernel would show a considerable speed improvement due to removing
> syscall and memory copy overhead. The system will be quite stressed, having
> 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

--
// Gianni Tedesco (gianni at scaramanga dot co dot uk)
lynx --source www.scaramanga.co.uk/gianni-at-ecsc.asc | gpg --import
8646BE7D: 6D9F 2287 870E A2C9 8F60 3A3C 91B5 7669 8646 BE7D
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