tracing: add subsystem level to trace events
authorSteven Rostedt <srostedt@redhat.com>
Sat, 28 Feb 2009 02:33:02 +0000 (21:33 -0500)
committerSteven Rostedt <srostedt@redhat.com>
Sat, 28 Feb 2009 07:59:43 +0000 (02:59 -0500)
commit6ecc2d1ca39177edb6fbdb7412948b0e9f409d02
tree336a12a2f3db016f967717e1cb06e9171a239ce5
parenteb594e45f6979cd10b18d87f7b3f02119e00a108
tracing: add subsystem level to trace events

If a trace point header defines TRACE_SYSTEM, then it will add the
following trace points into that event system.

If include/trace/irq_event_types.h has:

 #define TRACE_SYSTEM irq

at the top and

 #undef TRACE_SYSTEM

at the bottom, then a directory "irq" will be created in the
/debug/tracing/events directory. Inside that directory will contain the
two trace points that are defined in include/trace/irq_event_types.h.

Only adding the above to irq and not to sched, we get:

 # ls /debug/tracing/events/
irq                     sched_process_exit  sched_signal_send  sched_wakeup_new
sched_kthread_stop      sched_process_fork  sched_switch
sched_kthread_stop_ret  sched_process_free  sched_wait_task
sched_migrate_task      sched_process_wait  sched_wakeup

 # ls /debug/tracing/events/irq
irq_handler_entry  irq_handler_exit

If we add #define TRACE_SYSTEM sched to the trace/sched_event_types.h
then the rest of the trace events will be put in a sched directory
within the events directory.

I've been playing with this idea of the subsystem for a while, but
recently Tom Zanussi posted some patches to lkml that included this
method. Tom's approach was clean and got me to finally put some effort
to clean up the event trace points.

Thanks to Tom Zanussi for demonstrating how nice the subsystem
method is.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
kernel/trace/events.c
kernel/trace/trace_events.c
kernel/trace/trace_events.h