From: Marcelo Tosatti <mtosatti@redhat.com>
To: Peter Zijlstra <peterz@infradead.org>,
Frederic Weisbecker <frederic@kernel.org>
Cc: linux-kernel@vger.kernel.org, Marcelo Tosatti <mtosatti@redhat.com>
Subject: [patch 2/3] nohz: change signal tick dependency to wakeup CPUs of member tasks
Date: Thu, 28 Jan 2021 17:21:36 -0300 [thread overview]
Message-ID: <20210128202235.849263653@fuller.cnet> (raw)
In-Reply-To: 20210128202134.608115362@fuller.cnet
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 <mtosatti@redhat.com>
Index: linux-2.6/kernel/time/tick-sched.c
===================================================================
--- linux-2.6.orig/kernel/time/tick-sched.c
+++ linux-2.6/kernel/time/tick-sched.c
@@ -444,9 +444,20 @@ EXPORT_SYMBOL_GPL(tick_nohz_dep_clear_ta
* 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)
Index: linux-2.6/include/linux/tick.h
===================================================================
--- linux-2.6.orig/include/linux/tick.h
+++ linux-2.6/include/linux/tick.h
@@ -207,7 +207,7 @@ extern void tick_nohz_dep_set_task(struc
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);
@@ -252,11 +252,11 @@ static inline void tick_dep_clear_task(s
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)
@@ -284,7 +284,7 @@ static inline void tick_dep_set_task(str
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) { }
Index: linux-2.6/kernel/time/posix-cpu-timers.c
===================================================================
--- linux-2.6.orig/kernel/time/posix-cpu-timers.c
+++ linux-2.6/kernel/time/posix-cpu-timers.c
@@ -523,7 +523,7 @@ static void arm_timer(struct k_itimer *t
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_s
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,
next prev parent reply other threads:[~2021-01-28 20:26 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-28 20:21 [patch 0/3] nohz_full: only wakeup target CPUs when notifying new tick dependency (v5) Marcelo Tosatti
2021-01-28 20:21 ` [patch 1/3] nohz: only wakeup a single target cpu when kicking a task Marcelo Tosatti
2021-01-28 20:21 ` Marcelo Tosatti [this message]
2021-02-12 12:25 ` [patch 2/3] nohz: change signal tick dependency to wakeup CPUs of member tasks Frederic Weisbecker
2021-02-12 14:00 ` Marcelo Tosatti
2021-02-12 14:18 ` Frederic Weisbecker
2021-01-28 20:21 ` [patch 3/3] nohz: tick_nohz_kick_task: only IPI if remote task is running Marcelo Tosatti
2021-02-12 14:19 ` [patch 0/3] nohz_full: only wakeup target CPUs when notifying new tick dependency (v5) Frederic Weisbecker
-- strict thread matches above, loose matches on Subject: below --
2021-01-28 18:40 [patch 0/3] nohz_full: only wakeup target CPUs when notifying new tick dependency (v4) Marcelo Tosatti
2021-01-28 18:40 ` [patch 2/3] nohz: change signal tick dependency to wakeup CPUs of member tasks Marcelo Tosatti
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