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From: Frederic Weisbecker <frederic@kernel.org>
To: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@kernel.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	Marcelo Tosatti <mtosatti@redhat.com>,
	"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Yunfeng Ye <yeyunfeng@huawei.com>,
	Frederic Weisbecker <frederic@kernel.org>
Subject: [PATCH 07/10] tick/nohz: Change signal tick dependency to wakeup CPUs of member tasks
Date: Thu, 13 May 2021 01:29:21 +0200	[thread overview]
Message-ID: <20210512232924.150322-8-frederic@kernel.org> (raw)
In-Reply-To: <20210512232924.150322-1-frederic@kernel.org>

From: Marcelo Tosatti <mtosatti@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.

Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Yunfeng Ye <yeyunfeng@huawei.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Frederic Weisbecker <frederic@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 2258984a0e8a..0bb80a7f05b9 100644
--- a/include/linux/tick.h
+++ b/include/linux/tick.h
@@ -211,7 +211,7 @@ 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);
@@ -256,11 +256,11 @@ 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)
@@ -288,7 +288,7 @@ 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 3bb96a8b49c9..29a5e54e6e10 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 1991adf5a922..800719ea4045 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


  parent reply	other threads:[~2021-05-12 23:43 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-05-12 23:29 [GIT PULL] tick/nohz updates v3 Frederic Weisbecker
2021-05-12 23:29 ` [PATCH 01/10] tick/nohz: Evaluate the CPU expression after the static key Frederic Weisbecker
2021-05-13 13:17   ` [tip: timers/nohz] " tip-bot2 for Peter Zijlstra
2021-05-12 23:29 ` [PATCH 02/10] tick/nohz: Conditionally restart tick on idle exit Frederic Weisbecker
2021-05-13 13:17   ` [tip: timers/nohz] " tip-bot2 for Yunfeng Ye
2021-05-12 23:29 ` [PATCH 03/10] tick/nohz: Remove superflous check for CONFIG_VIRT_CPU_ACCOUNTING_NATIVE Frederic Weisbecker
2021-05-13 13:17   ` [tip: timers/nohz] " tip-bot2 for Frederic Weisbecker
2021-05-12 23:29 ` [PATCH 04/10] tick/nohz: Update idle_exittime on actual idle exit Frederic Weisbecker
2021-05-13 13:17   ` [tip: timers/nohz] " tip-bot2 for Yunfeng Ye
2021-05-12 23:29 ` [PATCH 05/10] tick/nohz: Update nohz_full Kconfig help Frederic Weisbecker
2021-05-13 13:17   ` [tip: timers/nohz] " tip-bot2 for Frederic Weisbecker
2021-05-12 23:29 ` [PATCH 06/10] tick/nohz: Only wakeup a single target cpu when kicking a task Frederic Weisbecker
2021-05-13 13:17   ` [tip: timers/nohz] tick/nohz: Only wake up " tip-bot2 for Frederic Weisbecker
2021-05-12 23:29 ` Frederic Weisbecker [this message]
2021-05-13 13:17   ` [tip: timers/nohz] tick/nohz: Change signal tick dependency to wake up CPUs of member tasks tip-bot2 for Marcelo Tosatti
2021-05-12 23:29 ` [PATCH 08/10] tick/nohz: Kick only _queued_ task whose tick dependency is updated Frederic Weisbecker
2021-05-13 13:17   ` [tip: timers/nohz] " tip-bot2 for Marcelo Tosatti
2021-05-12 23:29 ` [PATCH 09/10] tick/nohz: Call tick_nohz_task_switch() with interrupts disabled Frederic Weisbecker
2021-05-13 13:17   ` [tip: timers/nohz] " tip-bot2 for Peter Zijlstra
2021-05-12 23:29 ` [PATCH 10/10] MAINTAINERS: Add myself as context tracking maintainer Frederic Weisbecker
2021-05-19  9:21   ` [tip: timers/nohz] " tip-bot2 for Frederic Weisbecker
2021-05-13 12:23 ` [GIT PULL] tick/nohz updates v3 Ingo Molnar

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