trace_start - start collecting driver trace
void trace_start(string filename, int auto_stop_sec = 30)
Calling this function will start collecting tracing information from the
driver. This includes LPC function level execution information.
The trace collection will stop and write the json data to `filename` on
`trace_end()` or after `auto_stop_sec` seconds, which defaults to 30
seconds.
Note: do not leave tracing enabled for too long or you will risk running
out of memory.
To read and analyze the json file, use Chrome or Firefox Developer Tools
Performance tab.