In addition to the RW_TRACE_BUFFER_SIZE environment variable, the trace manager also looks at the RW_TRACE_LEVEL environment variable. This is another method of filtering trace events at runtime. The environment variable can be set to one of these values: FATAL, ERROR, WARNING, INFO, TEST, DEBUG, ENTRY.

Before forwarding the trace event, the trace manager looks at this environment variable and does not forward any event that is less severe than the level specified. This variable defaults to ENTRY, thus letting all the (compiled-in) events through. See Controlling Trace Output for a discussion of compile-time versus runtime filtering of trace events.