[PATCH] tick/nohz: Optimize check_tick_dependency() with early return

[Ionut Nechita (Sunlight Linux)]

Avoid iterating through individual tick dependency bits when the
tick_stop tracepoint is disabled, which is the common case. When
tracing is disabled, we can return immediately based on the atomic
value being zero or non-zero, skipping the per-bit evaluation.

This optimization improves the hot path performance of tick dependency
checks across all contexts (idle and non-idle), not just nohz_full CPUs.

Suggested-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Ionut Nechita <ionut_n2001@xxxxxxxxx>
---
 kernel/time/tick-sched.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 34b341b66f220..2c1236a1cd364 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -332,6 +332,9 @@ static bool check_tick_dependency(atomic_t *dep)
 {
 	int val = atomic_read(dep);
 
+	if (likely(!tracepoint_enabled(tick_stop)))
+		return !val;
+
 	if (val & TICK_DEP_MASK_POSIX_TIMER) {
 		trace_tick_stop(0, TICK_DEP_MASK_POSIX_TIMER);
 		return true;
-- 
2.52.0