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

[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@linutronix.de>
Signed-off-by: Ionut Nechita <ionut_n2001@yahoo.com>
---
 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

[tip: timers/core] tick/nohz: Optimize check_tick_dependency() with early return

[tip-bot2 for Ionut Nechita (Sunlight Linux)]

The following commit has been merged into the timers/core branch of tip:

Commit-ID:     8f9e1849402b34744cf3e4c8174b1907d1f99fe3
Gitweb:        https://git.kernel.org/tip/8f9e1849402b34744cf3e4c8174b1907d1f99fe3
Author:        Ionut Nechita (Sunlight Linux) <sunlightlinux@gmail.com>
AuthorDate:    Wed, 28 Jan 2026 09:45:43 +02:00
Committer:     Thomas Gleixner <tglx@kernel.org>
CommitterDate: Fri, 30 Jan 2026 09:59:34 +01:00

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 <ionut_n2001@yahoo.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://patch.msgid.link/20260128074558.15433-3-sunlightlinux@gmail.com
---
 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 8ddf74e..fd928d3 100644
--- 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;

[tip: timers/core] tick/nohz: Optimize check_tick_dependency() with early return

[tip-bot2 for Ionut Nechita (Sunlight Linux)]

The following commit has been merged into the timers/core branch of tip:

Commit-ID:     9328c0960f22e2499319e4e894abb98aa0f9d222
Gitweb:        https://git.kernel.org/tip/9328c0960f22e2499319e4e894abb98aa0f9d222
Author:        Ionut Nechita (Sunlight Linux) <sunlightlinux@gmail.com>
AuthorDate:    Wed, 28 Jan 2026 09:45:43 +02:00
Committer:     Thomas Gleixner <tglx@kernel.org>
CommitterDate: Fri, 30 Jan 2026 17:24:31 +01:00

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
---
 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 8ddf74e..fd928d3 100644
--- 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;

[tip: timers/core] tick/nohz: Optimize check_tick_dependency() with early return

[tip-bot2 for Ionut Nechita (Sunlight Linux)]

The following commit has been merged into the timers/core branch of tip:

Commit-ID:     56534673cea7f00d96a64deb58057298fe9f192e
Gitweb:        https://git.kernel.org/tip/56534673cea7f00d96a64deb58057298fe9f192e
Author:        Ionut Nechita (Sunlight Linux) <sunlightlinux@gmail.com>
AuthorDate:    Wed, 28 Jan 2026 09:45:43 +02:00
Committer:     Thomas Gleixner <tglx@kernel.org>
CommitterDate: Fri, 30 Jan 2026 22:13:13 +01:00

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
---
 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 8ddf74e..fd928d3 100644
--- 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;