Throughput

Description

The Throughput example allows the measurement of data throughput when receiving samples from a publisher.

Design

It consists of 2 units:

  • Publisher: sends samples at a specified size and rate.

  • Subscriber: Receives samples and outputs statistics about throughput

Scenario

The publisher sends samples and allows you to specify a payload size in bytes as well as allowing you to specify whether to send data in bursts. The publisher will continue to send data forever unless a time-out is specified.

Configurable:

  • payloadSize: the size of the payload in bytes

  • burstInterval: the time interval between each burst in ms

  • burstSize: the number of samples to send each burst

  • timeOut: the number of seconds the publisher should run for (0=infinite)

  • partitionName: the name of the partition

The subscriber will receive data and output the total amount received and the data-rate in bytes-per-second. It will also indicate if any samples were received out-of-order. A maximum number of cycles can be specified and once this has been reached the subscriber will terminate and output totals and averages.

The subscriber executable measures:

  • transferred: the total amount of data transferred in bytes.

  • outOfOrder: the number of samples that were received out of order.

  • transfer rate: the data transfer rate in bytes per second.

  • subscriber also calculates statistics on these values over a configurable number of cycles.

Configurable:

  • maxCycles: the number of times to output statistics before terminating

  • pollingDelay

  • partitionName: the name of the partition

Running the example

It is recommended that you run ping and pong in separate terminals to avoid mixing the output.

  • Open 2 terminals.

  • In the first terminal start Publisher by running publisher

    publisher usage (parameters must be supplied in order):

    ./publisher [payloadSize (bytes)] [burstInterval (ms)] [burstSize (samples)] [timeOut (seconds)] [partitionName]

    defaults:

    ./publisher 8192 0 1 0 "Throughput example"

  • In the second terminal start Ping by running subscriber

    subscriber usage (parameters must be supplied in order):

    ./subscriber [maxCycles (0=infinite)] [pollingDelay (ms, 0 = event based)] [partitionName]

    defaults:

    ./subscriber 0 0 "Throughput example"

  • To achieve optimal performance it is recommended to set the CPU affinity so that ping and pong run on separate CPU cores, and use real-time scheduling. In a Linux environment this can be achieved as follows:

    publisher usage:

    taskset -c 0 chrt -f 80 ./publisher [payloadSize (bytes)] [burstInterval (ms)] [burstSize (samples)] [timeOut (seconds)] [partitionName]

    subscriber usage:

    taskset -c 1 chrt -f 80 ./subscriber [maxCycles (0 = infinite)] [pollingDelay (ms, 0 = event based)] [partitionName]

    On Windows the CPU affinity and prioritized scheduling class can be set as follows:

    publisher usage:

    START /affinity 1 /high cmd /k "publisher.exe" [payloadSize (bytes)] [burstInterval (ms)] [burstSize (samples)] [timeOut (seconds)] [partitionName]

    subscriber usage:

    START /affinity 2 /high cmd /k "subscriber.exe" [maxCycles (0 = infinite)] [pollingDelay (ms, 0 = event based)] [partitionName]