Shared memory examples

Note

The configuration files from Shared memory configuration are a prerequisite for the following examples.

To start running Cyclone DDS with shared memory exchange:

1. Open three terminals.

2. In the first terminal, start RouDi:

   ~/iceoryx/build/iox-roudi -c iox_config.toml
   

3. In the second terminal, run the publisher.

   export LD_LIBRARY_PATH=~/iceoryx/install/lib/${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH}
   export CYCLONEDDS_URI=file://cyclonedds.xml
   ~/cyclonedds/build/bin/ShmThroughputPublisher 16384 0 1 10 "Throughput example"
   

4. In the third terminal, run the subscriber.

   export LD_LIBRARY_PATH=~/iceoryx/install/lib/${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH}
   export CYCLONEDDS_URI=file://cyclonedds.xml
   ~/cyclonedds/build/bin/ShmThroughputSubscriber 10 0 "Throughput example" 16384
   

   Note

   Both the publisher and subscriber must be given the same message type, which for this example is 16384 (the number of bytes in the message sent).

The following shows a typical result on the subscriber side:

Cycles: 10 | PollingDelay: 0 | Partition: Throughput example
=== [Subscriber] Waiting for samples...
=== [Subscriber] 1.000 Payload size: 16384 | Total received: 26587 samples, 435601408 bytes | Out of order: 0 samples Transfer rate: 26586.48 samples/s, 3484.74 Mbit/s
=== [Subscriber] 1.000 Payload size: 16384 | Total received: 51764 samples, 848101376 bytes | Out of order: 0 samples Transfer rate: 25176.43 samples/s, 3299.92 Mbit/s
=== [Subscriber] 1.000 Payload size: 16384 | Total received: 77666 samples, 1272479744 bytes | Out of order: 0 samples Transfer rate: 25901.57 samples/s, 3394.97 Mbit/s
=== [Subscriber] 1.000 Payload size: 16384 | Total received: 103328 samples, 1692925952 bytes | Out of order: 0 samples Transfer rate: 25661.24 samples/s, 3363.47 Mbit/s
=== [Subscriber] 1.000 Payload size: 16384 | Total received: 127267 samples, 2085142528 bytes | Out of order: 0 samples Transfer rate: 23938.74 samples/s, 3137.70 Mbit/s
=== [Subscriber] 1.000 Payload size: 16384 | Total received: 151643 samples, 2484518912 bytes | Out of order: 0 samples Transfer rate: 24375.11 samples/s, 3194.89 Mbit/s
=== [Subscriber] 1.000 Payload size: 16384 | Total received: 176542 samples, 2892464128 bytes | Out of order: 0 samples Transfer rate: 24898.70 samples/s, 3263.52 Mbit/s
=== [Subscriber] 1.000 Payload size: 16384 | Total received: 201916 samples, 3308191744 bytes | Out of order: 0 samples Transfer rate: 25373.31 samples/s, 3325.73 Mbit/s
=== [Subscriber] 1.000 Payload size: 16384 | Total received: 228113 samples, 3737403392 bytes | Out of order: 0 samples Transfer rate: 26196.68 samples/s, 3433.65 Mbit/s
=== [Subscriber] 1.000 Payload size: 16384 | Total received: 254555 samples, 4170629120 bytes | Out of order: 0 samples Transfer rate: 26441.99 samples/s, 3465.80 Mbit/s

Total received: 254555 samples, 4170629120 bytes
Out of order: 0 samples
Average transfer rate: 25455.50 samples/s, Maximum transfer rate: 26586.48 samples/s, Average throughput : 3336.50 Mbit/s
Maximum throughput : 3484.74 Mbit/s

Shared memory is especially suited for exchanging large messages:

The relative performances are dependant on a large number of factors such as:

• Message size

• iceoryx memory pool configuration

• Number of other exchanges taking place

• And so on

Individual results may therefore differ.