sampling-probability. You can set this to a value between 0 and 1 (both inclusive) to tell the tracer how often to record a trace for incoming requests. For example, if
sampling-probability = 0.1, then roughly 1 out of 10 requests will be traced. Regardless of this param's value, a trace can be force-recorded or force-suppressed using the
x-force-sampleheader parameter. See Recording Traces for details.