-Core concepts
-~~~~~~~~~~~~~
-An _instrumentation point_ is a point, within a piece of software,
-which, when executed, creates an LTTng _event_.
-
-LTTng offers various types of instrumentation; see the
-<<inst-point-type-cond,Instrumentation point type condition>> section
-below to learn about them.
-
-An _event rule_ is a set of conditions to match a set of events.
-
-When LTTng creates an event{nbsp}__E__, a event rule{nbsp}__ER__ is said
-to __match__{nbsp}__E__ when{nbsp}__E__ satisfies *all* the conditions
-of{nbsp}__ER__. This concept is similar to a regular expression which
-matches a set of strings.
-
-When an event rule matches an event, LTTng _emits_ the event,
-therefore attempting to execute one or more actions.
-
-[NOTE]
-====
-The event creation and emission processes are documentation concepts to
-help understand the journey from an instrumentation point to the
-execution of actions.
-
-The actual creation of an event can be costly because LTTng needs to
-evalute the arguments of the instrumentation point.
-
-In practice, LTTng implements various optimizations for the Linux kernel
-and user space tracing domains (option:--domain=++kernel++ and
-option:--domain=++user++ options) to avoid actually creating an event
-when the tracer knows, thanks to properties which are independent from
-the event payload and current context, that it would never emit such an
-event. Those properties are:
-
-* The instrumentation point type (see the
- <<inst-point-type-cond,Instrumentation point type>> section below).
-* The instrumentation point name (or event name)
- (see the <<event-name-cond,Event name condition>> section below).
-* The instrumentation point log level (see the
- <<inst-point-log-level-cond,Instrumentation point log level condition>>
- section below).
-
-In other words: if, for a given instrumentation point{nbsp}__IP__, the
-LTTng tracer knows that it would never emit an event,
-executing{nbsp}__IP__ represents a simple boolean variable check.
-====
-
-
-Event rule overview
-~~~~~~~~~~~~~~~~~~~