4. Running a program on the IPU¶
You can now run one of the example programs from the SDK. The Poplar examples
are in the directory
adder_ipu.cpp builds a simple graph to add two vectors together and return the result.
Make a copy of the
adderexample directory in your working directory
Compile the program
Run the program. It will produce the following output:
$ ./adder_ipu Creating graph Building engine v1 sum = 10 v2 sum = 65
4.1. Hardware and software monitoring¶
The IPU hardware, and any programs running on it, can be monitored and analysed in various ways.
4.1.1. Command line tools¶
The IPU driver software includes a number of software tools that provide information on the current status of the connected hardware. These include:
gc-info: determine what IPU devices are present in the system.
gc-monitor: passively monitor IPU activity and telemetry such as power draw, temperature and clock speed.
gc-reset: reset one or more IPU devices.
These are in the directory
The use of these tools is described in the IPU Command Line Tools document.
4.1.2. Trace output¶
When running a program, you have the option to output a trace from the running code which allows you to see the phases that the graph compiler uses when preparing and compiling the graph processes to execute on the IPU. Going back to the simple adder example in Running a program on the IPU, try running:
$ POPLAR_LOG_LEVEL=DEBUG ./adder_ipu
You will see each stage of the process listed before the program output appears. The logging options are documented in the Poplar & PopLibs User Guide.
4.1.3. Execution profiling¶
The PopVision analysis tools are available on the Graphcore software download portal.
The PopVision Graph Analyser provides a graphical view of the graph execution trace, showing memory use, tile mapping and other vital information to help you optimise your application.
The PopVision System Analyser provides information about the behaviour of the host-side application code. It shows an interactive graphical view of the timeline of execution steps, helping you to identify any bottlenecks between the CPUs and IPUs.
For more information see the PopVision User Guide.