Using Simulink

Profiler

The Simulink simulation profiler collects performance data while simulating your model and generates a report, called a simulation profile, based on the data. The simulation profile generated by the profiler shows you how much time Simulink spends executing each function required to simulate your model. The profile enables you to determine the parts of your model that require the most time to simulate and hence where to focus your model optimization efforts.

Note    You must have the Simulink Performance Tools option installed on your system to use the profiler.

How the Profiler Works

The following pseudocode summarizes the execution model on which the profiler is based.

• Sim() 
      ModelInitialize(). 
      ModelExecute() 
          for t = tStart to tEnd
          Output()
          Update()
          Integrate()
              Compute states from derivs by repeatedly calling: 
                   MinorOutput() 
                   MinorDeriv() 
              Locate any zero crossings by repeatedly calling: 
                   MinorOutput() 
                   MinorZeroCrossings() 
          EndIntegrate 
          Set time t = tNew. 
      EndModelExecute
      ModelTerminate
  EndSim 
  

According to this conceptual model, Simulink executes a Simulink model by invoking the following functions zero, one, or more times, depending on the function and the model.

Function	Purpose	Level
sim	Simulate the model. This top-level function invokes the other functions required to simulate the model. The time spent in this function is the total time required to simulate the model.	System
ModelInitialize	Set up the model for simulation.	System
ModelExecute	Execute the model by invoking the output, update, integrate, etc., functions for each block at each time step from the start to the end of simulation.	System
Output	Compute the outputs of a block at the current time step.	Block
Update	Update a block's state at the current time step.	Block
Integrate	Compute a block's continuous states by integrating the state derivatives at the current time step.	Block
MinorOutput	Compute a block's output at a minor time step.	Block
MinorDeriv	Compute a block's state derivatives at a minor time step.	Block
MinorZeroCrossings	Compute a block's zero-crossing values at a minor time step.	Block
ModelTerminate	Free memory and perform any other end-of-simulation cleanup.	System
Nonvirtual Subsystem	Compute the output of a nonvirtual subsystem (see Atomic Versus Virtual Subsystems) at the current time step by invoking the output, update, integrate, etc., functions for each block that it contains. The time spent in this function is the time required to execute the nonvirtual subsystem.	Block

The profiler measures the time required to execute each invocation of these functions and generates a report at the end of the model that describes how much time was spent in each function.

Enabling the Profiler

To profile a model, open the model and select Profiler from the Simulink Tools menu. Then start the simulation. When the simulation finishes, Simulink generates and displays the simulation profile for the model in the MATLAB help browser.

The Simulation Profile

Simulink stores the simulation profile in the MATLAB working directory.

The report has two sections: a summary and a detailed report.

Summary Section

The summary file displays the following performance totals.

Item	Description
Total Recorded Time	Total time required to simulate the model
Number of Block Methods	Total number of invocations of block-level functions (e.g., Output())
Number of Internal Methods	Total number of invocations of system-level functions (e.g., ModelExecute)
Number of Nonvirtual Subsystem Methods	Total number of invocations of nonvirtual subsystem functions
Clock Precision	Precision of the profiler's time measurement

The summary section then shows summary profiles for each function invoked to simulate the model. For each function listed, the summary profile specifies the following information.

Item	Description
Name	Name of function. This item is a hyperlink. Clicking it displays a detailed profile of this function.
Time	Total time spent executing all invocations of this function as an absolute value and as a percentage of the total simulation time
Calls	Number of times this function was invoked
Time/Call	Average time required for each invocation of this function, including the time spent in functions invoked by this function
Self Time	Average time required to execute this function, excluding time spent in functions called by this function
Location	Specifies the block or model executed for which this function is invoked. This item is a hyperlink. Clicking it highlights the corresponding icon in the model diagram. Note that the link works only if you are viewing the profile in the MATLAB help browser.

Detailed Profile Section

This section contains detailed profiles for each function invoked to simulate the model. Each detailed profile contains all the information shown in the summary profile for the function. In addition, the detailed profile displays the function (parent function) that invoked the profiled function and the functions (child functions) invoked by the profiled function. Clicking the name of the parent or a child function takes you to the detailed profile for that function.

Merging Model Differences

Model Coverage Tool