The timer function is included in the Executer object. It measures the time each start of a cycle (counter.tick()). Additionally it measures the run time of all threads with counter.tock(). The timer keeps track of previous measurements and calculates after each counter.tock minimal value, maximal value, mean value and the variance of the period time and run time as well.

Don't use log.trace() for data output during a real time critical process. This command introduces unwanted jitter. Use std::cout instead, which effects the jitter of the real time process much less. Don't use multiple lines (std:endl). Multiple line outputs introduces a significant jitter with a periodicity of 1 second.

This measurement provides only statistical data over 1000 (or 100) cycles at a time and not for each iteration. To measure jitter for each iteration use the signalProbeBlock.

It is possible to measure a 15% CPU load and over 300us run time per 1ms period. This indicates, that the run time measurement is not accurate.

To integrate the measurement, following code has to be integrated after a task is created and before the task is added to the Executor. Following example shows the integration of the measurement including creation and assignment to the executor of a control system:

using namespace eeros::logger;
 
 
 
eeros::task::Periodic td("control system",dt, timedomain);
 
td.monitors.push_back([&](eeros::PeriodicCounter &c, Logger<LogWriter> &log) {
	static int ticks = 0;			// mseconds				
 
	if (++ticks < 1000) return;		
	ticks = 0;
 
	// timing measurement (tictoc)
	eeros::PeriodicCounter counter = c;
	c.reset();
	std::cout 	<< "CS: period max: " << setw(7)  << counter.period.max*1000
			<< "   run max: " << std::setw(8) << counter.run.max*1000
			<< std::endl;
});
 
eeros::Executor::instance().add(td);

If the executor has a small cycle time (less than 1 second) it is not advisable to update the log output each time. In the implementation of the code example the output is only updated after 1000 cycles. Depending on the cycle time, this number can be adjusted in line 3.

Line 7 defines which date should be written to the terminal output. Following options are available for run time and period time:

• min
• max
• mean
• variance

The time is measured in nanoseconds.

Because of memory restriction or because writing a file would affect the real time behavior of the system it is maybe not possible to save the output of the terminal directly on the target system. The output can be saved on a different computer with following command:

ssh <username>@<hostname> "<path to eeros project>/eerosproject" > <path to logfile>/<name of logfile>

With this command it is possible to measure for multiple hours or even multiple days.