Capturing Performance Data :: Accelerating Models (Simulink®)

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Capturing Performance Data

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What Is the Profiler? How the Profiler Works Enabling the Profiler How to Save Simulink Profiler Results

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What Is the Profiler?

The profiler captures data while your model runs and identifies the parts of your model requiring the most time to simulate. You use this information to decide where to focus your model optimization efforts.

Note You cannot use the Rapid Accelerator mode with the Profiler.

Performance data showing the time spent executing each function in your model is placed in a report called the simulation profile.

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, your model is executed 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 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 Tools menu. Then start the simulation. When the simulation finishes, the Simulink code generates and displays the simulation profile for the model in the Help browser.

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. The link works only if you are viewing the profile in the 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.

Note Enabling the Profiler on a parent model does not enable profiling for referenced models. You must enable profiling separately for each submodel. Profiling occurs only if the submodel executes in Normal mode. See Referencing a Model for more information.

How to Save Simulink Profiler Results

You can save the Profiler report to a variable in the MATLAB workspace, and subsequently, to a mat file. At a later time, you can regenerate and review the report.

To save the Profiler report for a model vdp to the variable profile1 and to the data file report1.mat, complete the following steps:

In the Simulink Profiler Report window, click click here. Simulink saves the report data to the variable vdpProfileData.
Navigate to the MATLAB command window.
To review the report, at the command line enter:
```
slprofreport(vdpProfileData)
```
To save the data to a variable named profile1 in the base workspace, enter:
```
profile1 = vdpProfileData;
```
To save the data to a mat file named report1, enter:
```
save report1 profile1
```

To view the report at a later time, from the MATLAB command window, enter:

% Load the mat file and recreate the profile1 object
load report1
% Recreate the html report from the object
slprofreport(profile1);

Using the Accelerator Mode with the Simulink Debugger

Customizing the Simulink User Interface

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