Chapter 7. GProf Profile Plugin Support

To check whether the Linux Tools GProf plugin is installed, within Eclipse select from the menu Help → About Eclipse IDE and press the Installation Details button. Within the resulting dialog illustrated in Figure 7.1, “Eclipse Installation Details - GProf” look in the Configuration contents: section for “GProf Integration”. If present, the plugin is installed.

Figure 7.1. Eclipse Installation Details - GProf

To install the Linux Tools GProf plugin is installed you will need internet access. Within Eclipse select from the menu Help → Install New Software and within the Work with: field of the resulting dialog, enter the name of your Eclipse Installation and choose the download URL. An example illustration of the dialog is shown in Figure 7.2, “Eclipse Install GProf”. For example, “2018-09 - http://download.eclipse.org/releases/2018-09”.

Figure 7.2. Eclipse Install GProf

Select Performance, Profiling and Tracing Tools → GProf Integration and ensure the latter is checked. Select the Next button to confirm the install details followed by Next to confirm your acceptance of the license terms by selecting I accept the terms of the license agreement. Select the Finish button to confirm agreement and begin the installation process. On completion of the installation you will be required to restart Eclipse.

Open up your eCos configuration within the eCos Configuration Tool and select Build → Packages (Ctrl+P) and type gprof into the Keywords field as illustrated in Figure 7.3, “Configuration Tool Install GProf Package”.

Figure 7.3. Configuration Tool Install GProf Package

If already installed, the package Application profile support will appear in the right-hand column under Use these packages. If not installed, it will appear under the Available Packages column. In this case select the Add button to move the package to the right-hand column followed by selecting the OK button to accept the addition of the package. Finally select File → Save (Ctrl+S) to save your configuration followed optionally by Build → Library (F7) to rebuild the eCos library. The latter step is optional as Eclipse will rebuild the library as soon as you exit the eCos Configuration Tool if it detects a change in the active configuration file.

Open a command shell with the appropriate environment variables set and, assuming your eCos configuration is named ecos.ecc, the commands illustrated in Example 7.1, “Adding CYGPKG_PROFILE_GPROF with the command line” will add the CYGPKG_PROFILE_GPROF package and rebuild the eCos library.

$ ecosconfig add CYGPKG_PROFILE_GPROF 
$ ecosconfig tree
$ make

Normally the capture of profiling data from the target platform requires the temporary suspension of all code execution on the target platform while the data is extracted, either through the use of a GDB monitor or a hardware debugger.

However, if your eCos Configuration includes the FredBSD networking stack (the CYGPKG_NET_FREEBSD_STACK package) with the TFTP server option enabled (the default), the profiling data may be extracted from the target platform without temporarily suspending all code execution. This is achieved through the use of an additional low- priority eCos thread that provides a TFTP service (on port 69, the default) which allows the transfer of the profiling data from the target hardware to occur over TFTP. The eCos CYGPKG_PROFILE_GPROF package by default creates this thread when the CYGPKG_NET_FREEBSD_STACK package is enabled.

When capturing profiling data in this manner, the eCosPro CDT plug-in needs to be configured where the profiling data will be captured from, otherwise the default method through GDB is used. Open the debug launch configuration window you previously created to launch the binary in Section 4.1, “eCos Launch Configurations” and select the Profiling tab. This dialog is illustrated in Figure 7.4, “Profiling Data Capture through TFTP”.

Figure 7.4. Profiling Data Capture through TFTP

Check the Fetch data via TFTP instad of GDB (requires TFTP server on target) field and fill in appropriate values for the Hostname / IP address for the target platform's network address and Port number. The default port number set by the CYGPKG_NET_FREEBSD_STACK package for the TFTP server is 69.

You may enable this flag project-wide by bringing up the project's properties dialog as described in Section 5.3, “Application Project Properties”, and selecting C/C++ Build → Settings, selecting the Tool Settings tab in the right-hand panel and within tree of settings selecting either eCos gcc → Debugging or eCos g++ → Debugging whether you wish profiling data to be generated for either C or C++ code, or both. Check the Generate gprof information (-pg) field from the right-hand panel, apply the changes and close the dialog by pressing the Apply and OK buttons respectively. This is illustrated in Figure 7.5, “Enable Application Profiling Data Generation”.

Figure 7.5. Enable Application Profiling Data Generation

The -pg GNU compiler flag may also be enabled or disabled for individual source files by opening the properties dialog for each source file (similar to opening the application project's properties, but start by highlighting the source file within the Project Explorer window of the C/C++ perspective) and checking or unchecking the Generate gprof information (-pg) field.

eCos and eCosPro functions may also be included for profiling data generation and analysis. This may be acheived by adding the -pg GNU compiler flag to the value of CYGBLD_GLOBAL_CFLAGS configuration macro. To add or remove the flag, open the eCos configuration in the eCos Configuraion Tool as described in Section 6.2.1, “Editing the eCos configuration project”, and search using the Find in configuration dialog, reached through the menu options Edit → Find (Ctrl+F) for CYGBLD_GLOBAL_CFLAGS (as Find what) with Search in set to Macro Names. Once visible, left mouse click in the value field (or double-left click to bring up a String Edit dialog) and add or remove the -pg flag to/from the value as required.

Finally select File → Save (Ctrl+S) to save your configuration followed optionally by Build → Library (F7) to rebuild the eCos library.

The application must call the function profile_on to start the collection of profiling data. If the TFTP daemon is enabled, the call to profile_on must happen once the network is up and running, typically after the call to init_all_network_interfaces. This is because the TFTP daemon will be started within profile_on.

	Note
	profile_on may be invoked multiple times but each invocation will allocate a fresh profiling range, deleting the previous range.

A typical example is illustrated in Example 7.2, “Enable profiling data collection”.

#include <pkgconf/system.h>
#ifdef CYGPKG_NET
# include <network.h>
#endif
#ifdef CYGPKG_PROFILE_GPROF
# include <cyg/profile/profile.h>
#endif
…
int
main(int argc, char** argv)
{
    …
#ifdef CYGPKG_NET
    init_all_network_interfaces();
#endif
    …

#ifdef CYGPKG_PROFILE_GPROF
    {
        extern char _stext[], _etext[];
        profile_on(_stext, _etext, 16, 3500);
    }
#endif
    …
}

The profile_on function takes four arguments:

The collection of profiling data may be disabled by the application, using a call to profile_off. This will also reset any existing profile data. The function prototype is illustrated in Example 7.3, “profile_off prototype”.

void profile_off(void);

To capture the profiling data, select the application's process or one of the application's threads within the Debug Window of the Debug Perspective, and press the Take Profile Snapshot button called out as 1 in Figure 7.6, “Capture and Clear Profiling Data”.

This will extract the profiling data from the target, pausing and resuming execution if necessary, and save it to a file within the project explorer tree in the same directory as the binary executable. The file will have a .gmon extension with the date and time of the snapshot as the base name, allowing multiple snapshots to be taken and saved at different times.

	Note
	If you are using a software monitor (e.g. RedBoot) to debug your application and not a hardware debugger, and if the application is not already paused, the snapshot may not immediately be taken but may be delayed until the software monitor is active (e.g. when performing diagnostics output). This is also dependant on the eCos configuration.

To clear the profiling data, press the Reset Profile Data button called out as 2 in Figure 7.6, “Capture and Clear Profiling Data” when either the application's process or one of the application's threads within the Debug Window of the Debug Perspective is selected. Similar to the capturing of the data, this will pausie and resume execution of the application if necessary.