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charset="utf-8" Checking if a CPU is avoid can add a slight overhead and should be=20 done only when necessary.=20 Add a static key check which makes it almost nop when key is false.=20 Arch needs to set the key when it decides to. Refer to debug patch for example.=20 Signed-off-by: Shrikanth Hegde --- This method avoids additional ifdefs. So kept it that way instead of=20 CONFIG_PARAVIRT.=20 Added a helper function for cpu_avoid, since including sched.h fails in=20 cpumask.h kernel/sched/core.c | 8 ++++---- kernel/sched/fair.c | 5 +++-- kernel/sched/rt.c | 8 ++++---- kernel/sched/sched.h | 9 +++++++++ 4 files changed, 20 insertions(+), 10 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index aea4232e3ec4..51426b17ef55 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -148,9 +148,9 @@ __read_mostly int sysctl_resched_latency_warn_once =3D = 1; * Limited because this is done with IRQs disabled. */ __read_mostly unsigned int sysctl_sched_nr_migrate =3D SCHED_NR_MIGRATE_BR= EAK; - __read_mostly int scheduler_running; =20 +DEFINE_STATIC_KEY_FALSE(paravirt_cpu_avoid_enabled); #ifdef CONFIG_SCHED_CORE =20 DEFINE_STATIC_KEY_FALSE(__sched_core_enabled); @@ -2438,7 +2438,7 @@ static inline bool is_cpu_allowed(struct task_struct = *p, int cpu) return false; =20 /* CPU marked as avoid, shouldn't chosen to run any task*/ - if (cpu_avoid(cpu)) + if (cpu_avoid_check(cpu)) return false; =20 /* But are allowed during online. */ @@ -5578,7 +5578,7 @@ void sched_tick(void) sched_clock_tick(); =20 /* push the current task out if cpu is marked as avoid */ - if (cpu_avoid(cpu)) + if (cpu_avoid_check(cpu)) push_current_task(rq); =20 rq_lock(rq, &rf); @@ -8048,7 +8048,7 @@ void push_current_task(struct rq *rq) unsigned long flags; =20 /* idle task can't be pused out */ - if (rq->curr =3D=3D rq->idle || !cpu_avoid(rq->cpu)) + if (rq->curr =3D=3D rq->idle || !cpu_avoid_check(rq->cpu)) return; =20 /* Do for only SCHED_NORMAL AND RT for now */ diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 406288aef535..21370f76d61b 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -8547,7 +8547,7 @@ select_task_rq_fair(struct task_struct *p, int prev_c= pu, int wake_flags) rcu_read_unlock(); =20 /* Don't select a CPU marked as avoid for wakeup */ - if (cpu_avoid(new_cpu)) + if (cpu_avoid_check(new_cpu)) return cpu; else return new_cpu; @@ -11668,7 +11668,8 @@ static int sched_balance_rq(int this_cpu, struct rq= *this_rq, cpumask_and(cpus, sched_domain_span(sd), cpu_active_mask); =20 /* Don't spread load into CPUs marked as avoid */ - cpumask_andnot(cpus, cpus, cpu_avoid_mask); + if (static_branch_unlikely(¶virt_cpu_avoid_enabled)) + cpumask_andnot(cpus, cpus, cpu_avoid_mask); =20 schedstat_inc(sd->lb_count[idle]); =20 diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index fd9df6f46135..0ab3fdf7a637 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1549,7 +1549,7 @@ select_task_rq_rt(struct task_struct *p, int cpu, int= flags) if (!test && target !=3D -1 && !rt_task_fits_capacity(p, target)) goto out_unlock; =20 - if (cpu_avoid(target)) + if (cpu_avoid_check(target)) goto out_unlock; /* * Don't bother moving it if the destination CPU is @@ -1873,7 +1873,7 @@ static struct rq *find_lock_lowest_rq(struct task_str= uct *task, struct rq *rq) for (tries =3D 0; tries < RT_MAX_TRIES; tries++) { cpu =3D find_lowest_rq(task); =20 - if ((cpu =3D=3D -1) || (cpu =3D=3D rq->cpu) || cpu_avoid(cpu)) + if ((cpu =3D=3D -1) || (cpu =3D=3D rq->cpu) || cpu_avoid_check(cpu)) break; =20 lowest_rq =3D cpu_rq(cpu); @@ -1971,7 +1971,7 @@ static int push_rt_task(struct rq *rq, bool pull) return 0; =20 cpu =3D find_lowest_rq(rq->curr); - if (cpu =3D=3D -1 || cpu =3D=3D rq->cpu || cpu_avoid(cpu)) + if (cpu =3D=3D -1 || cpu =3D=3D rq->cpu || cpu_avoid_check(cpu)) return 0; =20 /* @@ -2234,7 +2234,7 @@ static void pull_rt_task(struct rq *this_rq) if (likely(!rt_overload_count)) return; =20 - if (cpu_avoid(this_rq->cpu)) + if (cpu_avoid_check(this_rq->cpu)) return; =20 /* diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index b9614873762e..707fdfa46772 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1710,6 +1710,15 @@ struct rq_flags { =20 extern struct balance_callback balance_push_callback; void push_current_task(struct rq *rq); +DECLARE_STATIC_KEY_FALSE(paravirt_cpu_avoid_enabled); + +static inline bool cpu_avoid_check(int cpu) +{ + if (static_branch_unlikely(¶virt_cpu_avoid_enabled)) + return cpu_avoid(cpu); + + return false; +} =20 #ifdef CONFIG_SCHED_CLASS_EXT extern const struct sched_class ext_sched_class; --=20 2.43.0