Default Events

Klogger has several base events, used to account for invocation times, buffer dump times, and the state of the system when the logging starts -- i.e. all the processes in the system.

These events are:

1. KLOGGER_START
   Logged whenever Klogger is enabled (the first event logged), saving the kernel version and the size of the memory resident buffer used per CPU.

2. KLOGGER_FINISH
   The reciprocal of the previous event. Simply marks when Klogger was stopped.

3. PROCESS_EXISTS
   When Klogger is enabled, all existing processes are logged, being the mainline of the system's status. This event is logged for each existing process, holding the process's general information: pid, scheduling priority, scheduling policy, and its command line. Admittedly, this event is pretty expensive overhead-wise, it is only logged once as part of the log's header.

4. LOGGING_EVENT
   A complement to the system status is Klogger's status, mainly the events that are being logged. Again, a LOGGING_EVENT is saved for each event name Klogger is configured to log.

5. DUMP_BEGIN
   This event is logged whenever Klogger dumps its memory resident buffer to the disk. Its main purpose is that post mortem analysis of the log can isolate event implicitly generated by Klogger itself. For example, when analyzing disk traffic, one would like to discard traffic generated by the measurement itself. This event also saved the dump index -- the index of the dump during the current logging session.

6. DUMP_FINISH
   Again, a reciprocal of the former, indicating the end of the buffer dump. Its payload also includes the number of bytes actually dumped.

7. MARK
   A special event being used to mark places in the log -- for example, a measurement can have several phases, whose transitions the user would like mark in the log. Generating this event is done by writing some number string into a special file: /proc/sys/klogger/mark. Doing this will cause the event to be logged, along with the logging process's pid and the number written into the file. The written number can be used by the user to separate the different MARK events.