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]