Trace Event Call Location

Trace events, each with a unique minor code, should be placed at the following locations within a component or subsystem performing a service as a result of an external API call:

• Pre-Invocation: At the beginning of any external interface before performing any actions or changing any data. This is considered pre-invocation of a service.

• Post-Invocation: Before returning from performing any service through an external interface. This is considered post-invocation of a service, and is significant since:

  a.

  Information may be returned to the caller which is of interest for problem determination
  b.
  It causes a "service completion" event to be added to the trace buffer which may be paired with the pre-invocation trace event
  3.
  Other: Events within a component should be considered as points of interest for tracing when they may be used for problem determination within the component or subsystem. These include:

  a.

  Significant changes in the state of the machine.
  b.
  Significant changes in the state of the system. System state changes are usually those which affect system data structures. These structures are those which are referenced by more than one component or which represent significant system resources.
  c.
  Allocation or deallocation of a resource managed by a component performing a service

  This detail is determined and assigned by each component or subsystem owner.

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