diff options
| -rw-r--r-- | include/linux/sched/nohz.h | 2 | ||||
| -rw-r--r-- | kernel/sched/core.c | 63 | ||||
| -rw-r--r-- | kernel/sched/fair.c | 56 | ||||
| -rw-r--r-- | kernel/sched/loadavg.c | 33 | ||||
| -rw-r--r-- | kernel/sched/psi.c | 3 | ||||
| -rw-r--r-- | kernel/sched/sched.h | 15 |
6 files changed, 119 insertions, 53 deletions
diff --git a/include/linux/sched/nohz.h b/include/linux/sched/nohz.h index 1abe91ff6e4a..6d67e9a5af6b 100644 --- a/include/linux/sched/nohz.h +++ b/include/linux/sched/nohz.h @@ -15,9 +15,11 @@ static inline void nohz_balance_enter_idle(int cpu) { } #ifdef CONFIG_NO_HZ_COMMON void calc_load_nohz_start(void); +void calc_load_nohz_remote(struct rq *rq); void calc_load_nohz_stop(void); #else static inline void calc_load_nohz_start(void) { } +static inline void calc_load_nohz_remote(struct rq *rq) { } static inline void calc_load_nohz_stop(void) { } #endif /* CONFIG_NO_HZ_COMMON */ diff --git a/kernel/sched/core.c b/kernel/sched/core.c index fc1dfc007604..1a9983da4408 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -552,27 +552,32 @@ void resched_cpu(int cpu) */ int get_nohz_timer_target(void) { - int i, cpu = smp_processor_id(); + int i, cpu = smp_processor_id(), default_cpu = -1; struct sched_domain *sd; - if (!idle_cpu(cpu) && housekeeping_cpu(cpu, HK_FLAG_TIMER)) - return cpu; + if (housekeeping_cpu(cpu, HK_FLAG_TIMER)) { + if (!idle_cpu(cpu)) + return cpu; + default_cpu = cpu; + } rcu_read_lock(); for_each_domain(cpu, sd) { - for_each_cpu(i, sched_domain_span(sd)) { + for_each_cpu_and(i, sched_domain_span(sd), + housekeeping_cpumask(HK_FLAG_TIMER)) { if (cpu == i) continue; - if (!idle_cpu(i) && housekeeping_cpu(i, HK_FLAG_TIMER)) { + if (!idle_cpu(i)) { cpu = i; goto unlock; } } } - if (!housekeeping_cpu(cpu, HK_FLAG_TIMER)) - cpu = housekeeping_any_cpu(HK_FLAG_TIMER); + if (default_cpu == -1) + default_cpu = housekeeping_any_cpu(HK_FLAG_TIMER); + cpu = default_cpu; unlock: rcu_read_unlock(); return cpu; @@ -1442,17 +1447,6 @@ void check_preempt_curr(struct rq *rq, struct task_struct *p, int flags) #ifdef CONFIG_SMP -static inline bool is_per_cpu_kthread(struct task_struct *p) -{ - if (!(p->flags & PF_KTHREAD)) - return false; - - if (p->nr_cpus_allowed != 1) - return false; - - return true; -} - /* * Per-CPU kthreads are allowed to run on !active && online CPUs, see * __set_cpus_allowed_ptr() and select_fallback_rq(). @@ -3669,28 +3663,32 @@ static void sched_tick_remote(struct work_struct *work) * statistics and checks timeslices in a time-independent way, regardless * of when exactly it is running. */ - if (idle_cpu(cpu) || !tick_nohz_tick_stopped_cpu(cpu)) + if (!tick_nohz_tick_stopped_cpu(cpu)) goto out_requeue; rq_lock_irq(rq, &rf); curr = rq->curr; - if (is_idle_task(curr) || cpu_is_offline(cpu)) + if (cpu_is_offline(cpu)) goto out_unlock; + curr = rq->curr; update_rq_clock(rq); - delta = rq_clock_task(rq) - curr->se.exec_start; - /* - * Make sure the next tick runs within a reasonable - * amount of time. - */ - WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3); + if (!is_idle_task(curr)) { + /* + * Make sure the next tick runs within a reasonable + * amount of time. + */ + delta = rq_clock_task(rq) - curr->se.exec_start; + WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3); + } curr->sched_class->task_tick(rq, curr, 0); + calc_load_nohz_remote(rq); out_unlock: rq_unlock_irq(rq, &rf); - out_requeue: + /* * Run the remote tick once per second (1Hz). This arbitrary * frequency is large enough to avoid overload but short enough @@ -7063,8 +7061,15 @@ void sched_move_task(struct task_struct *tsk) if (queued) enqueue_task(rq, tsk, queue_flags); - if (running) + if (running) { set_next_task(rq, tsk); + /* + * After changing group, the running task may have joined a + * throttled one but it's still the running task. Trigger a + * resched to make sure that task can still run. + */ + resched_curr(rq); + } task_rq_unlock(rq, tsk, &rf); } @@ -7260,7 +7265,7 @@ capacity_from_percent(char *buf) &req.percent); if (req.ret) return req; - if (req.percent > UCLAMP_PERCENT_SCALE) { + if ((u64)req.percent > UCLAMP_PERCENT_SCALE) { req.ret = -ERANGE; return req; } diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index fe4e0d775375..3c8a379c357e 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -3516,7 +3516,6 @@ update_cfs_rq_load_avg(u64 now, struct cfs_rq *cfs_rq) * attach_entity_load_avg - attach this entity to its cfs_rq load avg * @cfs_rq: cfs_rq to attach to * @se: sched_entity to attach - * @flags: migration hints * * Must call update_cfs_rq_load_avg() before this, since we rely on * cfs_rq->avg.last_update_time being current. @@ -5912,6 +5911,20 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target) (available_idle_cpu(prev) || sched_idle_cpu(prev))) return prev; + /* + * Allow a per-cpu kthread to stack with the wakee if the + * kworker thread and the tasks previous CPUs are the same. + * The assumption is that the wakee queued work for the + * per-cpu kthread that is now complete and the wakeup is + * essentially a sync wakeup. An obvious example of this + * pattern is IO completions. + */ + if (is_per_cpu_kthread(current) && + prev == smp_processor_id() && + this_rq()->nr_running <= 1) { + return prev; + } + /* Check a recently used CPU as a potential idle candidate: */ recent_used_cpu = p->recent_used_cpu; if (recent_used_cpu != prev && @@ -8658,10 +8671,6 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s /* * Try to use spare capacity of local group without overloading it or * emptying busiest. - * XXX Spreading tasks across NUMA nodes is not always the best policy - * and special care should be taken for SD_NUMA domain level before - * spreading the tasks. For now, load_balance() fully relies on - * NUMA_BALANCING and fbq_classify_group/rq to override the decision. */ if (local->group_type == group_has_spare) { if (busiest->group_type > group_fully_busy) { @@ -8701,16 +8710,37 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s env->migration_type = migrate_task; lsub_positive(&nr_diff, local->sum_nr_running); env->imbalance = nr_diff >> 1; - return; - } + } else { - /* - * If there is no overload, we just want to even the number of - * idle cpus. - */ - env->migration_type = migrate_task; - env->imbalance = max_t(long, 0, (local->idle_cpus - + /* + * If there is no overload, we just want to even the number of + * idle cpus. + */ + env->migration_type = migrate_task; + env->imbalance = max_t(long, 0, (local->idle_cpus - busiest->idle_cpus) >> 1); + } + + /* Consider allowing a small imbalance between NUMA groups */ + if (env->sd->flags & SD_NUMA) { + unsigned int imbalance_min; + + /* + * Compute an allowed imbalance based on a simple + * pair of communicating tasks that should remain + * local and ignore them. + * + * NOTE: Generally this would have been based on + * the domain size and this was evaluated. However, + * the benefit is similar across a range of workloads + * and machines but scaling by the domain size adds + * the risk that lower domains have to be rebalanced. + */ + imbalance_min = 2; + if (busiest->sum_nr_running <= imbalance_min) + env->imbalance = 0; + } + return; } diff --git a/kernel/sched/loadavg.c b/kernel/sched/loadavg.c index 28a516575c18..de22da666ac7 100644 --- a/kernel/sched/loadavg.c +++ b/kernel/sched/loadavg.c @@ -231,16 +231,11 @@ static inline int calc_load_read_idx(void) return calc_load_idx & 1; } -void calc_load_nohz_start(void) +static void calc_load_nohz_fold(struct rq *rq) { - struct rq *this_rq = this_rq(); long delta; - /* - * We're going into NO_HZ mode, if there's any pending delta, fold it - * into the pending NO_HZ delta. - */ - delta = calc_load_fold_active(this_rq, 0); + delta = calc_load_fold_active(rq, 0); if (delta) { int idx = calc_load_write_idx(); @@ -248,6 +243,24 @@ void calc_load_nohz_start(void) } } +void calc_load_nohz_start(void) +{ + /* + * We're going into NO_HZ mode, if there's any pending delta, fold it + * into the pending NO_HZ delta. + */ + calc_load_nohz_fold(this_rq()); +} + +/* + * Keep track of the load for NOHZ_FULL, must be called between + * calc_load_nohz_{start,stop}(). + */ +void calc_load_nohz_remote(struct rq *rq) +{ + calc_load_nohz_fold(rq); +} + void calc_load_nohz_stop(void) { struct rq *this_rq = this_rq(); @@ -268,7 +281,7 @@ void calc_load_nohz_stop(void) this_rq->calc_load_update += LOAD_FREQ; } -static long calc_load_nohz_fold(void) +static long calc_load_nohz_read(void) { int idx = calc_load_read_idx(); long delta = 0; @@ -323,7 +336,7 @@ static void calc_global_nohz(void) } #else /* !CONFIG_NO_HZ_COMMON */ -static inline long calc_load_nohz_fold(void) { return 0; } +static inline long calc_load_nohz_read(void) { return 0; } static inline void calc_global_nohz(void) { } #endif /* CONFIG_NO_HZ_COMMON */ @@ -346,7 +359,7 @@ void calc_global_load(unsigned long ticks) /* * Fold the 'old' NO_HZ-delta to include all NO_HZ CPUs. */ - delta = calc_load_nohz_fold(); + delta = calc_load_nohz_read(); if (delta) atomic_long_add(delta, &calc_load_tasks); diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c index ac4bd0ca11cc..028520702717 100644 --- a/kernel/sched/psi.c +++ b/kernel/sched/psi.c @@ -1199,6 +1199,9 @@ static ssize_t psi_write(struct file *file, const char __user *user_buf, if (static_branch_likely(&psi_disabled)) return -EOPNOTSUPP; + if (!nbytes) + return -EINVAL; + buf_size = min(nbytes, sizeof(buf)); if (copy_from_user(buf, user_buf, buf_size)) return -EFAULT; diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 1a88dc8ad11b..9ea647835fd6 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -896,7 +896,7 @@ struct rq { */ unsigned long nr_uninterruptible; - struct task_struct *curr; + struct task_struct __rcu *curr; struct task_struct *idle; struct task_struct *stop; unsigned long next_balance; @@ -2479,3 +2479,16 @@ static inline void membarrier_switch_mm(struct rq *rq, { } #endif + +#ifdef CONFIG_SMP +static inline bool is_per_cpu_kthread(struct task_struct *p) +{ + if (!(p->flags & PF_KTHREAD)) + return false; + + if (p->nr_cpus_allowed != 1) + return false; + + return true; +} +#endif |