tick/nohz: Optimize check_tick_dependency() with early return

There is no point in iterating through individual tick dependency bits when
the tick_stop tracepoint is disabled, which is the common case.

When the trace point is disabled, 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@linutronix.de>
Signed-off-by: Ionut Nechita (Sunlight Linux) <sunlightlinux@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260128074558.15433-3-sunlightlinux@gmail.com

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 8ddf74e705d35c0b84e3c2bd1597c1a758a5887f..fd928d374cfce41b9d3f9807bdfdde892663abd2 100644 (file)
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -344,6 +344,9 @@ 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;