MATLAB Examples

Assigning Tasks to Cores for Multicore Programming

This example shows how to take advantage of executing code on a multicore processor by graphical partitioning. This example requires Simulink Coder™ to generate multithreaded code.

Contents

Introduction

Multicore programming allows you to make use of the processing power of modern multicore processors to create high-performance applications. Simulink™ allows you to take advantage of multicore programming by allowing you to graphically partition your algorithms and to assign the code generated from those partitions to parallel threads on your multicore processor.

The parallel threads are typically scheduled by an operating system, assigning threads to cores dynamically. This allows the scheduler to make good use of the cores while providing a notion of fairness. However, in many applications, you may need additional control on how the cores are used or you may want to dedicate a set of cores to specific logic, for example to improve determinism. This level of control is achievable through graphical partitioning and is illustrated in this example.

Try the Example

A typical situation for multicore consists of a multi-rate model for which you want to assign code for the fast rates to one core and the code for the slower rates to other cores. This may allow you to add more logic to these faster rates or to achieve more determinism. More generally, you may want to dedicate cores to application logic with the greatest demand on resources. To begin, open the multicore project:

slexMulticoreExample

Generate Multithreaded Code

This application model is already partitioned into four concurrent tasks through the Concurrent Execution dialog which you may access from the Solvers pane of the model's Configuration Parameters. Use this dialog to specify logic, task and core assignments. In this example, we have partitioned the application logic as:

Double-click on the 'Generate Code and Profile Report' button to generate multi-threaded code, and profile its execution. This action runs and instruments the generated executable and produces both profiling results and a core occupancy map, the latter illustrated below. The illustration shows how the cores were utilized at each time step of execution. In this example, the first core was used for the fast rates (Task1 and Task2) and the second core was used for the slower rates (Task3 and Task4).

You may go back to the Concurrent Execution dialog to try out different core assignments. In particular, you may try to specify no core affinity by leaving the 'Affinity' property as '[]'. This is the default setting which allows Simulink™ to generate multi-threaded code suitable for dynamic scheduling on your multicore processor.