Enable qemu tracing. For this to work requires running everything inside
the qemu emulator; otherwise, this method will have no effect. The trace
file is specified on the command line when the emulator is started. For
example, the following command line
emulator -trace foo
will start running the emulator and create a trace file named "foo". This
method simply enables writing the trace records to the trace file.
The main differences between this and Debug.StartMethodTracing are that tracing in the qemu emulator traces every cpu instruction of every process, including kernel code, so we have more complete information, including all context switches. We can also get more detailed information such as cache misses. The sequence of calls is determined by post-processing the instruction trace. The qemu tracing is also done without modifying the application or perturbing the timing of calls because no instrumentation is added to the application being traced.
One limitation of using this method compared to using Debug.StartMethodTracing on the real device is that the emulator does not model all of the real hardware effects such as memory and bus contention. The emulator also has a simple cache model and cannot capture all the complexities of a real cache.