Enabling and Disabling Tracing

The final step in starting up tracing is to globally enable kernel tracing. When you do this, the probes you have enabled write records into the kernel trace buffer as they are encountered.

prex> ktrace			        # check tracing status 	
Tracing is off 	
prex> ktrace on			     # enable kernel tracing 	
prex>

To trace the kernel behavior of your application (perhaps with user-level tracing enabled as well), start it running at this time. When your application finishes, or when you decide you have enough trace data to sample its behavior, globally disable kernel tracing.

prex> ktrace off		     # disable kernel tracing 	
prex> 

The trace buffer is still present in the kernel. Copy it out into a TNF file using tnfxtract. The procedure that you follow is explained in the subsection " Extracting Kernel Trace Data (tnfxtract)".