84 lines
2.8 KiB
ReStructuredText
84 lines
2.8 KiB
ReStructuredText
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Copyright(c) 2006 to 2018 ADLINK Technology Limited and others
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This program and the accompanying materials are made available under the
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terms of the Eclipse Public License v. 2.0 which is available at
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http://www.eclipse.org/legal/epl-2.0, or the Eclipse Distribution License
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v. 1.0 which is available at
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http://www.eclipse.org/org/documents/edl-v10.php.
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SPDX-License-Identifier: EPL-2.0 OR BSD-3-Clause
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Roundtrip
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==========
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Description
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***********
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The Roundtrip example allows the measurement of roundtrip duration when sending and receiving back a single message.
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Design
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******
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It consists of 2 units:
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- Pong: waits for messages from ping and sends the same message back.
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- Ping: Sends a message to pong and waits for its return.
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Scenario
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********
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A message is sent by the **ping** executable on the "PING" partition, which the **pong** executable is waiting for.
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The **pong** executable sends the same message back on the "PONG" partition, which the **ping** executable is waiting for.
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This sequence is repeated a configurable number of times.
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The **ping** executable measures:
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- writeAccess time: time the write() method took.
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- readAccess time: time the take() method took.
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- roundTrip time: time between the call to the write() method and the return of the take() method.
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- **ping** also calculates min/max/average statistics on these values over a configurable number of samples and/or time out period.
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Configurable:
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- payloadSize: the size of the payload in bytes.
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- numSamples: the number of samples to send.
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- timeOut: the number of seconds ping should run for.
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Running the example
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*******************
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It is recommended that you run ping and pong in separate terminals to avoid mixing the output.
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- Open 2 terminals.
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- In the first terminal start Pong by running pong.
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pong usage:
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``./pong``
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- In the second terminal start Ping by running ping.
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ping usage (parameters must be supplied in order):
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``./ping [payloadSize (bytes, 0 - 655536)] [numSamples (0 = infinite)] [timeOut (seconds, 0 = infinite)]``
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``./ping quit - ping sends a quit signal to pong.``
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defaults:
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``./ping 0 0 0``
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- To achieve optimal performance it is recommended to set the CPU affinity so that ping and pong run on separate CPU cores,
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and use real-time scheduling. In a Linux environment this can be achieved as follows:
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pong usage:
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``taskset -c 0 chrt -f 80 ./pong``
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ping usage:
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``taskset -c 1 chrt -f 80 ./ping [payloadSize (bytes, 0 - 655536)] [numSamples (0 = infinite)] [timeOut (seconds, 0 = infinite)]``
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On Windows the CPU affinity and scheduling class can be set as follows:
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pong usage:
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``START /affinity 1 /high cmd /k "pong.exe"``
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ping usage:
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``START /affinity 2 /high cmd /k "ping.exe" [payloadSize (bytes, 0 - 655536)] [numSamples (0 = infinite)] [timeOut (seconds, 0 = infinite)]``
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