CPU Sampling

With the sampling method, mBProfiler records at a specified period of time the call traces of the threads of the executed application. The sampling method is recommended for large applications working for a long period of time (such as servers).

The advantage of this method is that it is much more scalable than the timing one. The sampler can also detect performance bottlenecks within methods because it is not based on method invocations. The disadvantage of this profiling technique is that it is less precise than the timing one, and does not record the number of method calls.

Turn Sampling On

To set up the sampling method to be your way for collecting CPU profiling information:

1. Go to the CPU Call Tree view.
2. In the right upper corner of the view, open the pull-down menu.
3. Switch to Sampling Mode.

   

or

1. Go to Window > Preferences (or to Eclipse >Preferences if you are using OS X) > mBProfiler .
2. In the Preferences window, check the sampling option under CPU method.

   

   Next to the sampling option, in the Sampling interval text field if needed change the period of time for taking samples.

3. Click OK.

   If this setting is changed after the CPU profiling has already begun, it will take effect the next time you start profiling.

You can additionally configure CPU profiling on top of the sampling method by using the following options:

• Use real CPU time in the mBProfiler preference page and in the pull-down menu in the CPU Call Tree view. This option defines if mBProfiler will show the real time of CPU usage, or the total execution time of the tested thread/method. For example, let's have a thread that was started at 1:30 PM and stopped at 2:30 PM. However, the thread wasn't active all the time but only for a total of 5 minutes (did some work and caused CPU usage). If the Use real CPU time option is not checked, mBProfiler will show a whole 1 hour of work for the tested thread. If that option is checked, however, mBProfiler will show only 5 minutes of work for the thread.

If the profiler agent does not support real CPU profiling, the mBProfiler will show an error in the CPU Call Tree view:

"Real CPU profiling is not supported for this platform"