QNX messaging vs. TCP/IP

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#1

Is there and data on the relative efficiencies of QNX messaging vs. TCP/IP?
Any comments would be appreciated.

Thanks,

Kevin

#2

On Thu, 24 Jul 2003 17:16:21 -0400, Kevin Miller
<kevin.miller@transcore.com> wrote:

Is there and data on the relative efficiencies of QNX messaging vs.
TCP/IP?
Any comments would be appreciated.

Thanks,

Kevin

Here are a couple of non-scientific observations that might help:

  1. We wrote a library that tries to implement S/R/R semantics using a
    TCP/IP transport. It was far from complete when we abandoned it, as
    tests showed that it would be 1/20th the speed of native S/R/R over the
    network, and even worse on a local transmission.

  2. Andre Koppel wrote a library that implements S/R/R in TCP/IP for
    Linux. We tested it against our SRRIPC kernel module, and the TCP/IP
    implementation was 1/5000th the speed of the SRRIPC module on the
    local machine. There is no networking in the SRRIPC kernel module,
    and we did not test Andre’s library vs. native QNX messaging on the
    network. For reference, the SRRIPC kernel module is a nearly-perfect
    source-level replacement for the QNX4 messaging API on Linux.

  3. Bitctrl.de sells a product calls QoIP (QNX over IP), which appears
    to use native messaging for local messages (SRRIPC in Linux, S/R/R in
    QNX 4 and 6), and UDP over the network. I am very interested in
    testing this, but I haven’t received my copy yet. Of all the possible
    solutions to QNX messaging over TCP/IP, this one seems to be the only
    candidate I have seen for good throughput and adherence to the QNX
    semantics.

  4. The Linux SIMPL project is an approximation of QNX S/R/R semantics
    using TCP/IP and UNIX sockets. The interface is a little odd, but it
    does a good job - about 1/2 the speed of the SRRIPC module, which is
    itself about 1/2 the speed of native QNX messaging. I have not tested
    its network performance.

Hope this helps,
Andrew

#3

Kevin Miller <kevin.miller@transcore.com> wrote:

Is there and data on the relative efficiencies of QNX messaging vs. TCP/IP?
Any comments would be appreciated.

For local interactions, S/R/R will be more than twice the speed of
TCP/IP.

Over a network, it will vary. QNX S/R/R will probably be better
in a completely dependable environment – but get into a lossy
network, and TCP/IP will handle it better. Also, QNX networking
is not routable, which can greatly limit the network distance
you can reach. (The protocol is bridgeable, though.)

-David

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