[PATCH v9 05/32] tracing/timers: Add tracepoint for tracking timer base is_idle flag

Anna-Maria Behnsen
2023-12-01T09:27:29Z

When debugging timer code the timer tracepoints are very important. There
is no tracepoint when the is_idle flag of the timer base changes. Instead
of always adding manually trace_printk(), add tracepoints which can be
easily enabled whenever required.

Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
---
v9: New in v9
---
include/trace/events/timer.h | 20 ++++++++++++++++++++
kernel/time/timer.c | 2 ++
2 files changed, 22 insertions(+)

diff --git a/include/trace/events/timer.h b/include/trace/events/timer.h
index 99ada928d445..1ef58a04fc57 100644
--- a/include/trace/events/timer.h
+++ b/include/trace/events/timer.h
@@ -142,6 +142,26 @@ DEFINE_EVENT(timer_class, timer_cancel,
TP_ARGS(timer)
);

+TRACE_EVENT(timer_base_idle,
+
+ TP_PROTO(bool is_idle, unsigned int cpu),
+
+ TP_ARGS(is_idle, cpu),
+
+ TP_STRUCT__entry(
+ __field( bool, is_idle )
+ __field( unsigned int, cpu )
+ ),
+
+ TP_fast_assign(
+ __entry->is_idle = is_idle;
+ __entry->cpu = cpu;
+ ),
+
+ TP_printk("is_idle=%d cpu=%d",
+ __entry->is_idle, __entry->cpu)
+);
+
#define decode_clockid(type) \
__print_symbolic(type, \
{ CLOCK_REALTIME, "CLOCK_REALTIME" }, \
diff --git a/kernel/time/timer.c b/kernel/time/timer.c
index a81d793a43d0..46a9b96a3976 100644
--- a/kernel/time/timer.c
+++ b/kernel/time/timer.c
@@ -1964,6 +1964,7 @@ u64 get_next_timer_interrupt(unsigned long basej, u64 basem)
if ((expires - basem) > TICK_NSEC)
base->is_idle = true;
}
+ trace_timer_base_idle(base->is_idle, base->cpu);
raw_spin_unlock(&base->lock);

return cmp_next_hrtimer_event(basem, expires);
@@ -1985,6 +1986,7 @@ void timer_clear_idle(void)
* the lock in the exit from idle path.
*/
base->is_idle = false;
+ trace_timer_base_idle(0, smp_processor_id());
}
#endif

--
2.39.2