Questions about Optimizing network I/O

From: Vadim Lebedev
Date: Tue Jul 01 2014 - 11:30:14 EST


Hello,

I'm looking for advice on optimizing a SOCKS proxy software which i modified
to support TCP <=> UDP tunnelling.
The modification of standard SOCKS protocol is pretty straightforward, i've
added a command that tells to socks server that destination socket is a UDP
socket so the server expects the tcp packets for this destination to be
prefixed with 4 byte length. The server reads the length prefix the reads the
'length' bytes for the tcp stream and send the data (without the length
prefix) to the destination address as UDP datagram.
The return path (from UDP to TCP) is even simpler: The server read UDP
datagram into a buffer whre 4 bytes are reserved for length prefix, fill
this prefix with the length of just read packet and send the buffer to the
tcp socket.

When testing my SOCKS server i see that the TCP -> UDP processing generates a
lot o CPU load while UDP -> TCP or normal SOCKS TCP <=> TCP processing
generates relatively light cpu load.

So i'm looking for the way to optimize TCP -> UDP path.
My idea is to write a kernel module which will define an ioctl with 2 params
TCP_fd and UDP_fd and will do TCP to UDP processing completely in kernel mode
without copying data frmo/to skbufs....


Any ideas about this approach?

Thanks
Vadim

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