From: Steven Rostedt 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 --- kernel/trace/events.c | 4 +++ kernel/trace/trace_events.c | 48 +++++++++++++++++++++++++++++++++++++++++++ kernel/trace/trace_events.h | 2 + 3 files changed, 54 insertions(+), 0 deletions(-) diff --git a/kernel/trace/events.c b/kernel/trace/events.c index 46e27ad..4e4e458 100644 --- a/kernel/trace/events.c +++ b/kernel/trace/events.c @@ -2,6 +2,10 @@ * This is the place to register all trace points as events. */ +/* someday this needs to go in a generic header */ +#define __STR(x) #x +#define STR(x) __STR(x) + #include #include "trace_events.h" diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 3bcb9df..1933220 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -345,11 +345,59 @@ static struct dentry *event_trace_events_dir(void) return d_events; } +struct event_subsystem { + struct list_head list; + const char *name; + struct dentry *entry; +}; + +static LIST_HEAD(event_subsystems); + +static struct dentry * +event_subsystem_dir(const char *name, struct dentry *d_events) +{ + struct event_subsystem *system; + + /* First see if we did not already create this dir */ + list_for_each_entry(system, &event_subsystems, list) { + if (strcmp(system->name, name) == 0) + return system->entry; + } + + /* need to create new entry */ + system = kmalloc(sizeof(*system), GFP_KERNEL); + if (!system) { + pr_warning("No memory to create event subsystem %s\n", + name); + return d_events; + } + + system->entry = debugfs_create_dir(name, d_events); + if (!system->entry) { + pr_warning("Could not create event subsystem %s\n", + name); + kfree(system); + return d_events; + } + + system->name = name; + list_add(&system->list, &event_subsystems); + + return system->entry; +} + static int event_create_dir(struct ftrace_event_call *call, struct dentry *d_events) { struct dentry *entry; + /* + * If the trace point header did not define TRACE_SYSTEM + * then the system would be called "TRACE_SYSTEM". + */ + if (strcmp(call->system, "TRACE_SYSTEM") != 0) + d_events = event_subsystem_dir(call->system, d_events); + call->dir = debugfs_create_dir(call->name, d_events); if (!call->dir) { pr_warning("Could not create debugfs " diff --git a/kernel/trace/trace_events.h b/kernel/trace/trace_events.h index deb95e5..b015d7b 100644 --- a/kernel/trace/trace_events.h +++ b/kernel/trace/trace_events.h @@ -7,6 +7,7 @@ struct ftrace_event_call { char *name; + char *system; struct dentry *dir; int enabled; int (*regfunc)(void); @@ -44,6 +45,7 @@ static struct ftrace_event_call __used \ __attribute__((__aligned__(4))) \ __attribute__((section("_ftrace_events"))) event_##call = { \ .name = #call, \ + .system = STR(TRACE_SYSTEM), \ .regfunc = ftrace_reg_event_##call, \ .unregfunc = ftrace_unreg_event_##call, \ } -- 1.5.6.5 -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/