The actions associated with speculative tracing are speculate(), commit(), and discard(). These actions are discussed in Chapter 13, Speculative Tracing.
void exit(int status)
The exit() action is used to immediately stop tracing, and to inform the DTrace consumer that it should cease tracing, perform any final processing, and call exit(3C) with the status specified. Because exit() returns a status to user-level, it is a data recording action, However, unlike other data storing actions, exit() cannot be speculatively traced. exit() will cause the DTrace consumer to exit regardless of buffer policy. Because exit() is a data recording action, it can be dropped.
When exit() is called, only DTrace actions already in progress on other CPUs will be completed. No new actions will occur on any CPU. The only exception to this rule is the processing of the END probe, which will be called after the DTrace consumer has processed the exit() action and indicated that tracing should stop.