From: Marcelo Tosatti <mtosa...@redhat.com>
Rather than waking up all nohz_full CPUs on the system, only wakeup
the target CPUs of member threads of the signal.
Reduces interruptions to nohz_full CPUs.
Signed-off-by: Marcelo Tosatti <mtosa...@redhat.com>
Cc: Yunfeng Ye <yeyunf...@huawei.com>
Cc: Peter Zijlstra <pet...@infradead.org>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Rafael J. Wysocki <rafael.j.wyso...@intel.com>
Signed-off-by: Frederic Weisbecker <frede...@kernel.org>
---
include/linux/tick.h | 8 ++++----
kernel/time/posix-cpu-timers.c | 4 ++--
kernel/time/tick-sched.c | 15 +++++++++++++--
3 files changed, 19 insertions(+), 8 deletions(-)
diff --git a/include/linux/tick.h b/include/linux/tick.h
index bfc96cbe955c..9e71ab1889aa 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -215,7 +215,7 @@ extern void tick_nohz_dep_set_task(struct task_struct *tsk,
enum tick_dep_bits bit);
extern void tick_nohz_dep_clear_task(struct task_struct *tsk,
enum tick_dep_bits bit);
-extern void tick_nohz_dep_set_signal(struct signal_struct *signal,
+extern void tick_nohz_dep_set_signal(struct task_struct *tsk,
enum tick_dep_bits bit);
extern void tick_nohz_dep_clear_signal(struct signal_struct *signal,
enum tick_dep_bits bit);
@@ -260,11 +260,11 @@ static inline void tick_dep_clear_task(struct task_struct
*tsk,
if (tick_nohz_full_enabled())
tick_nohz_dep_clear_task(tsk, bit);
}
-static inline void tick_dep_set_signal(struct signal_struct *signal,
+static inline void tick_dep_set_signal(struct task_struct *tsk,
enum tick_dep_bits bit)
{
if (tick_nohz_full_enabled())
- tick_nohz_dep_set_signal(signal, bit);
+ tick_nohz_dep_set_signal(tsk, bit);
}
static inline void tick_dep_clear_signal(struct signal_struct *signal,
enum tick_dep_bits bit)
@@ -293,7 +293,7 @@ static inline void tick_dep_set_task(struct task_struct
*tsk,
enum tick_dep_bits bit) { }
static inline void tick_dep_clear_task(struct task_struct *tsk,
enum tick_dep_bits bit) { }
-static inline void tick_dep_set_signal(struct signal_struct *signal,
+static inline void tick_dep_set_signal(struct task_struct *tsk,
enum tick_dep_bits bit) { }
static inline void tick_dep_clear_signal(struct signal_struct *signal,
enum tick_dep_bits bit) { }
diff --git a/kernel/time/posix-cpu-timers.c b/kernel/time/posix-cpu-timers.c
index a71758e34e45..932e0cb4b57b 100644
--- a/kernel/time/posix-cpu-timers.c
+++ b/kernel/time/posix-cpu-timers.c
@@ -523,7 +523,7 @@ static void arm_timer(struct k_itimer *timer, struct
task_struct *p)
if (CPUCLOCK_PERTHREAD(timer->it_clock))
tick_dep_set_task(p, TICK_DEP_BIT_POSIX_TIMER);
else
- tick_dep_set_signal(p->signal, TICK_DEP_BIT_POSIX_TIMER);
+ tick_dep_set_signal(p, TICK_DEP_BIT_POSIX_TIMER);
}
/*
@@ -1358,7 +1358,7 @@ void set_process_cpu_timer(struct task_struct *tsk,
unsigned int clkid,
if (*newval < *nextevt)
*nextevt = *newval;
- tick_dep_set_signal(tsk->signal, TICK_DEP_BIT_POSIX_TIMER);
+ tick_dep_set_signal(tsk, TICK_DEP_BIT_POSIX_TIMER);
}
static int do_cpu_nanosleep(const clockid_t which_clock, int flags,
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 8457f15a5073..a866fd8e7bb5 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -444,9 +444,20 @@ EXPORT_SYMBOL_GPL(tick_nohz_dep_clear_task);
* Set a per-taskgroup tick dependency. Posix CPU timers need this in order to
elapse
* per process timers.
*/
-void tick_nohz_dep_set_signal(struct signal_struct *sig, enum tick_dep_bits
bit)
+void tick_nohz_dep_set_signal(struct task_struct *tsk,
+ enum tick_dep_bits bit)
{
- tick_nohz_dep_set_all(&sig->tick_dep_mask, bit);
+ int prev;
+ struct signal_struct *sig = tsk->signal;
+
+ prev = atomic_fetch_or(BIT(bit), &sig->tick_dep_mask);
+ if (!prev) {
+ struct task_struct *t;
+
+ lockdep_assert_held(&tsk->sighand->siglock);
+ __for_each_thread(sig, t)
+ tick_nohz_kick_task(t);
+ }
}
void tick_nohz_dep_clear_signal(struct signal_struct *sig, enum tick_dep_bits
bit)
--
2.25.1
