

THE MT_CUBIT EXAMPLE
--------------------

This directory contains the source code for the TAO "MT_Cubit"
benchmark, which enables us to measure the real-time performance of
TAO.  MT_Cubit measures the latency, jitter, determinism, CPU
utilization, and degree of priority inversion incurred by TAO twoway
operations invoked under different workloads and priorities.  For
more information and empirical results, please see

http://www.cs.wustl.edu/~schmidt/PDF/RT-perf.pdf
http://www.cs.wustl.edu/~schmidt/PDF/RT-OS.pdf

COMPILING
---------

Makefile is provided.  Use make to compile.

You can either run the server in the background in the same window as
the client or open a separate window for the client and server.

OPTIONS
-------
Options are case sensitive, e.g., "-U" has a different meaning than "-u".

(1) server:

./server [-e <endpoint>]                // Endpoint to use (URL style endpoint)
         [-t <number_of_servants>]      // # of servant threads to create
         [-f <ior_file> ]               // specify a file to output all ior's
         [-m ]                          // Use multiple priorities for threads
         [-r ]                          // Run the thread-per-rate test

[-e <endpoint>] indicates the endpoint the ORB should bind to.
  This is useful when a machine has more than one network interface.

        Default Value: Whatever the current active pluggable protocol
                       uses as its default endpoint.

[-t <number_of_servants>] tells the server how many servants to create.

        Default Value: 2

[-f <ior_file> ] Use to specify a file to write all the iors from the
  different servants out to disk.

        Default Value: nil, which means not to write the iors to disk.

[-m ] For the 1 to n low priority servants, this parameter indicates
  the use of a range of priorities for the threads.

        Default Value: Disabled.  One priority will be used for the
                       low priority threads.

[-r] turn on the thread-per-rate tests.  (Priority inversion tests)

        Default Value: Disabled.

The server will print the IOR of the servants, but it is not required
by the client.

(2) client:

./client [<ORB OPTIONS>]        // ORB options, e.g., "-ORBObjRefStyle url"
         [-d <datatype>]        // what datatype to use for calls
         [-n <num_calls>]       // number of CORBA calls to make.
         [-t <num_of_clients>]  // number of client threads to create
         [-f <ior_file>]        // specify the file from which we read the object references (iors), if any.
         [-r]                   // run thread-per-rate test.
         [-o]                   // makes client use oneway calls.  By default, twoway calls are used.
         [-x]                   // makes a call to servant to shutdown
         [-u <requests> ]       // run the client utilization test for a number of <requests>.
         [-1]                   // run the one-to-n test.
         [-g <granularity>]     // choose the granularity of the timing of CORBA calls
         [-c]                   // run the number of context switches test.
         [-m]                   // use multiple priorities for the low priority clients.

[-d <datatype>]  <datatype> is one of the following:

   0 Octet
   1 Short
   2 Long
   3 Struct of the above 3 types

        Default Value: 0

[-n <num_calls>] is the number of CORBA twoway calls to be made

        Default Value: 1000

[-t <num_of_clients>] is the total number of concurrent clients to be
   created. The clients will have successively decreasing
   priorities if "-m" is specified.

        Default Value: 2

[-f <ior_file> ] Use to specify a file to read the object references (iors) of the
  different servants from disk.

        Default Value: nil, which means not to read the iors from disk.

[-r] run the thread-per-rate test.  (Priority inversion tests)

        Default Value: Disabled.

[-o] enables oneway calls instead of two-way calls.  The oneway call
   is a noop call (for now).

        Default Value: Disabled

[-x] makes the client call the shutdown() method on the servant which in turn
   invokes the shutdown() method on the ORB and causes it to exit gracefully.

        Default Value: Disabled

[-u <seconds>] runs the client/server utilization test for a number of <requests>.
        The output is the number of seconds for the test to make such number of requests.
        Now run the same test but with the -l option to make the same number of requests,
        this time not using CORBA, instead directly making function calls.  The difference
        in time for each test to make the same number of requests is the utilization of
        the OS/ORB combined.
     (Note: This option overrides any specified "-t" option)

        Default Value: Disabled

[-1] runs one-to-n test.  One servant services all low priority clients.

        Default Value: Disabled

[-g <granularity>] choose the granularity of timing the CORBA calls.
  This option should disappear sometime in the future, together with
  all the modifications done to support this.

  What happens when this options is not used, is that (1) we start a
  timer, (2) invoke the CORBA call, (3) stop the timer after call
  returns.  Some platforms have a very coarse grain timer (e.g. 10
  msec) and timing individual calls does not report very accurate
  latency results.

  This option enables a way to (1) start the timer, (2) invoke
  <granularity> calls, and (3) stop the timer.  This way, we get a
  better sense of the average latency of the CORBA calls.

  The downside is that the mechanism to enforce the frequency of calls
  (i.e., 20 Hz, 10Hz, etc) is in conflict with this option.  Such
  mechanism depends on the individual time for each call to enforce
  the calling frequency.

        Default Value: 1  (time each CORBA call)

[-c] Obtain number of context switches.

        Default Value: Disabled

[-m] Use multiple priorities for the low priority client

        Default Value: Disabled.  Will use one priority for all low priority clients.

Running on VxWorks
------------------

A typical run of the server and client on a single VxWorks target:

  -> iam "<your login>"
  -> ld < server
  -> ld < client
  -> spa server, "-f", "ior.txt", "-t", "2"
  -> spa client, "-f", "ior.txt", "-t", "2", "-n", "1000"

RESULTS
-------

The client prints the latency observed by the high priority client,
and the average latency observed by the low priority clients. Jitter
(standard deviation of the latency) is also printed by the client.


Running MT_Cubit on CHORUS:
--------------------------

1.You should make sure that you set the HOST environment variable on the
Chorus VME Board to the IP address of that Board before you run
MT_Cubit test.

e.g
$rsh tambora1 setenv HOST 128.252.165.82

2. You should make sure that the path to IOR file has write permission
for ALL.

server:
------
$rsh host_name arun path_to_server -e iiop://DOTTED_DECIMAL_ADDRESS:0
 -f path_to_ior_file -ORBDottedDecimalAddresses 1 <server_options>

Since Chorus doesn't support DNS, you should pass
dotted_decimal_address of the server machine to -e option.

You DONT have to use -ORBDottedDecimalAddresses 1 if you have
TAO_USE_DOTTED_DECIMAL_ADDRESSES defined in your config.h file.

e.g
$rsh tambora1 arun /MT_Cubit/server -e iiop://128.252.165.82:0 -f /ior
-ORBDottedDecimalAddresses 1 -t 10 -ORBObjRefStyle url

client:
-------

$rsh host_name arun  path_to_client -f path_to_ior_file <client_options>

e.g

$rsh tambora2 arun /MT_Cubit/client -f /ior -t 10 -n 300
