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tick/nohz: Change signal tick dependency to wake up CPUs of member tasks

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Rather than waking up all nohz_full CPUs on the system, only wake up
the target CPUs of member threads of the signal.

Reduces interruptions to nohz_full CPUs.

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210512232924.150322-8-frederic@kernel.org
This commit is contained in:
Marcelo Tosatti 2021-05-13 01:29:21 +02:00 committed by Ingo Molnar
parent 29721b8592
commit 1e4ca26d36
3 changed files with 19 additions and 8 deletions
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8
include/linux/tick.h
View File

@ -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) { }

4
kernel/time/posix-cpu-timers.c
View File

@ -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,

15
kernel/time/tick-sched.c
View File

@ -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)