Change Details

This is in the spirit of the long-dead _FAST eventhandlers that were removed in r126466. The existing eventhandler code is entirely dynamic in that it is safe to, for example, register a handler for a non-existent eventhandler lists. In order to achieve this eventhandler lists are added to a global list which is synchronized by a global mutex. When handlers are triggered via EVENTHANDLER_INVOKE a locked search of this list is done to find the appropriate list. Most, if not all, of the eventhandler lists do not require being dynamic in this fashion, as it is possible to statically define the list with the invokers. This allows the _INVOKE path to avoid a locked search of a global linked list, and instead execute the handlers on the specific list directly. The list must simply be available (i.e. linkable) from the invoker. To convert a list to being static it must be declared with EVENTHANDLER_STATIC_DECLARE, it must be defined in the appropriate compilation unit with EVENTHANDLER_STATIC_DEFINE, and the invoker must be changed to EVENTHANDLER_STATIC_INVOKE. EVENTHANDLER_STATIC_DEFINE has the additional duty of using SYSINIT(9) to add the statically-defined list to the global eventhandler list. This is done for simplicity, and it allows all eventhandlers to be registered with EVENTHANDLER_REGISTER regardless of whether the list is defined statically or not. There is no need to optimize this call as it is relatively infrequent. This commit also converts the various proc_* and thread_* eventhandler lists to being static. These eventhandler lists cause a lot of unnecessary cycles spent waiting on the global eventhandler lock in certain process and thread-heavy workloads (e.g. bulk ports builds). Adding reviewers I think might be interested, feel free to suggest others.

This introduces a facility to EVENTHANDLER(9) for explicitly defining a reference to an event handler list. This is useful since previously all invokers of events had to do a locked traversal of the global list of event handler lists in order to find the appropriate event handler list. By keeping a pointer to the appropriate list an invoker can avoid this traversal completely. The pointer is initialized with SYSINIT(9) during the eventhandler stage. Users registering interest in events do not need to know if the event is backed by such a list, since the list is added to the global list of lists as normal. As with lists that are not pre-defined it is safe to register for the events before the list has been created. This converts the process_* and thread_* events to using the new facility, as these are events whose traversals end up showing up significantly in ports build workflows. It may be advantageous to convert other events to using the new facility as well.

This is in the spirit of the long-dead _FAST eventhandlers that were removed in r126466. The existing eventhandler code is entirely dynamic in that it is safe to, for example, register a handler for a non-existent eventhandler lists. In order to achieve this eventhandler lists are added to a global list which is synchronized by a global mutex. When handlers are triggered via EVENTHANDLER_INVOKE a locked search of this list is done to find the appropriate list. Most, if not all,ntroduces a facility to EVENTHANDLER(9) for explicitly defining a reference to an event handler list. of the eventhandler lists do not require being dynamic in this fashion,This is useful since previously all invokers of events had to do a locked traversal of the global list of event handler lists in order to find the appropriate event handler list. as it is possibleBy keeping a pointer to statically define the list with the invokersthe appropriate list an invoker can avoid this traversal completely. This allows the _INVOKE path to avoid a locked search of a global linked list,The pointer is initialized with SYSINIT(9) during the eventhandler stage. and instead execute the handlers onUsers registering interest in events do not need to know if the specific list directly.event is backed by such a list, Tsince the list must simply be available (i.eis added to the global list of lists as normal. linkable) from As with lists that are not pre-defined it is safe to register for the events before the invokerlist has been created. To convert a list to being static it must be declared with EVENTHANDLER_STATIC_DECLARE, it must be defined in the appropriate compilation unit with EVENTHANDLER_STATIC_DEFINE, and the invoker must be changed to EVENTHANDLER_STATIC_INVOKE. EVENTHANDLER_STATIC_DEFINE has the additional duty of using SYSINIT(9) to add the statically-defined list to the global eventhandler list. This is done for simplicity, and it allows all eventhandlers to be registered with EVENTHANDLER_REGISTER regardless of whether the list is defined statically or not. There is no need to optimize this call as it is relatively infrequent. This commit also converts the various proc_* and thread_* eventhandler lists to being static. These eventhandler lists cause a lot of unnecessary cycles spent waiting on the global eventhandler lock in certain process and thread-heavy workloads (e.g.his converts the process_* and thread_* events to using the new facility, bulk ports builds). Adding reviewers I think might be interested,as these are events whose traversals end up showing up significantly in ports build workflows. feel freeIt may be advantageous to convert other events to suggest othersusing the new facility as well.