diff options
Diffstat (limited to 'kernel/sched/core.c')
| -rw-r--r-- | kernel/sched/core.c | 406 |
1 files changed, 385 insertions, 21 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index ff74fca39ed2..ca2bb629595f 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -355,8 +355,9 @@ static enum hrtimer_restart hrtick(struct hrtimer *timer) static void __hrtick_restart(struct rq *rq) { struct hrtimer *timer = &rq->hrtick_timer; + ktime_t time = rq->hrtick_time; - hrtimer_start_expires(timer, HRTIMER_MODE_ABS_PINNED_HARD); + hrtimer_start(timer, time, HRTIMER_MODE_ABS_PINNED_HARD); } /* @@ -380,7 +381,6 @@ static void __hrtick_start(void *arg) void hrtick_start(struct rq *rq, u64 delay) { struct hrtimer *timer = &rq->hrtick_timer; - ktime_t time; s64 delta; /* @@ -388,9 +388,7 @@ void hrtick_start(struct rq *rq, u64 delay) * doesn't make sense and can cause timer DoS. */ delta = max_t(s64, delay, 10000LL); - time = ktime_add_ns(timer->base->get_time(), delta); - - hrtimer_set_expires(timer, time); + rq->hrtick_time = ktime_add_ns(timer->base->get_time(), delta); if (rq == this_rq()) __hrtick_restart(rq); @@ -3478,7 +3476,7 @@ out: /** * try_invoke_on_locked_down_task - Invoke a function on task in fixed state - * @p: Process for which the function is to be invoked. + * @p: Process for which the function is to be invoked, can be @current. * @func: Function to invoke. * @arg: Argument to function. * @@ -3496,12 +3494,11 @@ out: */ bool try_invoke_on_locked_down_task(struct task_struct *p, bool (*func)(struct task_struct *t, void *arg), void *arg) { - bool ret = false; struct rq_flags rf; + bool ret = false; struct rq *rq; - lockdep_assert_irqs_enabled(); - raw_spin_lock_irq(&p->pi_lock); + raw_spin_lock_irqsave(&p->pi_lock, rf.flags); if (p->on_rq) { rq = __task_rq_lock(p, &rf); if (task_rq(p) == rq) @@ -3518,7 +3515,7 @@ bool try_invoke_on_locked_down_task(struct task_struct *p, bool (*func)(struct t ret = func(p, arg); } } - raw_spin_unlock_irq(&p->pi_lock); + raw_spin_unlock_irqrestore(&p->pi_lock, rf.flags); return ret; } @@ -4971,7 +4968,7 @@ static void __sched notrace __schedule(bool preempt) schedule_debug(prev, preempt); - if (sched_feat(HRTICK)) + if (sched_feat(HRTICK) || sched_feat(HRTICK_DL)) hrtick_clear(rq); local_irq_disable(); @@ -5265,6 +5262,12 @@ asmlinkage __visible void __sched notrace preempt_schedule(void) NOKPROBE_SYMBOL(preempt_schedule); EXPORT_SYMBOL(preempt_schedule); +#ifdef CONFIG_PREEMPT_DYNAMIC +DEFINE_STATIC_CALL(preempt_schedule, __preempt_schedule_func); +EXPORT_STATIC_CALL_TRAMP(preempt_schedule); +#endif + + /** * preempt_schedule_notrace - preempt_schedule called by tracing * @@ -5317,8 +5320,197 @@ asmlinkage __visible void __sched notrace preempt_schedule_notrace(void) } EXPORT_SYMBOL_GPL(preempt_schedule_notrace); +#ifdef CONFIG_PREEMPT_DYNAMIC +DEFINE_STATIC_CALL(preempt_schedule_notrace, __preempt_schedule_notrace_func); +EXPORT_STATIC_CALL_TRAMP(preempt_schedule_notrace); +#endif + #endif /* CONFIG_PREEMPTION */ +#ifdef CONFIG_PREEMPT_DYNAMIC + +#include <linux/entry-common.h> + +/* + * SC:cond_resched + * SC:might_resched + * SC:preempt_schedule + * SC:preempt_schedule_notrace + * SC:irqentry_exit_cond_resched + * + * + * NONE: + * cond_resched <- __cond_resched + * might_resched <- RET0 + * preempt_schedule <- NOP + * preempt_schedule_notrace <- NOP + * irqentry_exit_cond_resched <- NOP + * + * VOLUNTARY: + * cond_resched <- __cond_resched + * might_resched <- __cond_resched + * preempt_schedule <- NOP + * preempt_schedule_notrace <- NOP + * irqentry_exit_cond_resched <- NOP + * + * FULL: + * cond_resched <- RET0 + * might_resched <- RET0 + * preempt_schedule <- preempt_schedule + * preempt_schedule_notrace <- preempt_schedule_notrace + * irqentry_exit_cond_resched <- irqentry_exit_cond_resched + */ + +enum { + preempt_dynamic_none = 0, + preempt_dynamic_voluntary, + preempt_dynamic_full, +}; + +static int preempt_dynamic_mode = preempt_dynamic_full; + +static int sched_dynamic_mode(const char *str) +{ + if (!strcmp(str, "none")) + return 0; + + if (!strcmp(str, "voluntary")) + return 1; + + if (!strcmp(str, "full")) + return 2; + + return -1; +} + +static void sched_dynamic_update(int mode) +{ + /* + * Avoid {NONE,VOLUNTARY} -> FULL transitions from ever ending up in + * the ZERO state, which is invalid. + */ + static_call_update(cond_resched, __cond_resched); + static_call_update(might_resched, __cond_resched); + static_call_update(preempt_schedule, __preempt_schedule_func); + static_call_update(preempt_schedule_notrace, __preempt_schedule_notrace_func); + static_call_update(irqentry_exit_cond_resched, irqentry_exit_cond_resched); + + switch (mode) { + case preempt_dynamic_none: + static_call_update(cond_resched, __cond_resched); + static_call_update(might_resched, (typeof(&__cond_resched)) __static_call_return0); + static_call_update(preempt_schedule, (typeof(&preempt_schedule)) NULL); + static_call_update(preempt_schedule_notrace, (typeof(&preempt_schedule_notrace)) NULL); + static_call_update(irqentry_exit_cond_resched, (typeof(&irqentry_exit_cond_resched)) NULL); + pr_info("Dynamic Preempt: none\n"); + break; + + case preempt_dynamic_voluntary: + static_call_update(cond_resched, __cond_resched); + static_call_update(might_resched, __cond_resched); + static_call_update(preempt_schedule, (typeof(&preempt_schedule)) NULL); + static_call_update(preempt_schedule_notrace, (typeof(&preempt_schedule_notrace)) NULL); + static_call_update(irqentry_exit_cond_resched, (typeof(&irqentry_exit_cond_resched)) NULL); + pr_info("Dynamic Preempt: voluntary\n"); + break; + + case preempt_dynamic_full: + static_call_update(cond_resched, (typeof(&__cond_resched)) __static_call_return0); + static_call_update(might_resched, (typeof(&__cond_resched)) __static_call_return0); + static_call_update(preempt_schedule, __preempt_schedule_func); + static_call_update(preempt_schedule_notrace, __preempt_schedule_notrace_func); + static_call_update(irqentry_exit_cond_resched, irqentry_exit_cond_resched); + pr_info("Dynamic Preempt: full\n"); + break; + } + + preempt_dynamic_mode = mode; +} + +static int __init setup_preempt_mode(char *str) +{ + int mode = sched_dynamic_mode(str); + if (mode < 0) { + pr_warn("Dynamic Preempt: unsupported mode: %s\n", str); + return 1; + } + + sched_dynamic_update(mode); + return 0; +} +__setup("preempt=", setup_preempt_mode); + +#ifdef CONFIG_SCHED_DEBUG + +static ssize_t sched_dynamic_write(struct file *filp, const char __user *ubuf, + size_t cnt, loff_t *ppos) +{ + char buf[16]; + int mode; + + if (cnt > 15) + cnt = 15; + + if (copy_from_user(&buf, ubuf, cnt)) + return -EFAULT; + + buf[cnt] = 0; + mode = sched_dynamic_mode(strstrip(buf)); + if (mode < 0) + return mode; + + sched_dynamic_update(mode); + + *ppos += cnt; + + return cnt; +} + +static int sched_dynamic_show(struct seq_file *m, void *v) +{ + static const char * preempt_modes[] = { + "none", "voluntary", "full" + }; + int i; + + for (i = 0; i < ARRAY_SIZE(preempt_modes); i++) { + if (preempt_dynamic_mode == i) + seq_puts(m, "("); + seq_puts(m, preempt_modes[i]); + if (preempt_dynamic_mode == i) + seq_puts(m, ")"); + + seq_puts(m, " "); + } + + seq_puts(m, "\n"); + return 0; +} + +static int sched_dynamic_open(struct inode *inode, struct file *filp) +{ + return single_open(filp, sched_dynamic_show, NULL); +} + +static const struct file_operations sched_dynamic_fops = { + .open = sched_dynamic_open, + .write = sched_dynamic_write, + .read = seq_read, + .llseek = seq_lseek, + .release = single_release, +}; + +static __init int sched_init_debug_dynamic(void) +{ + debugfs_create_file("sched_preempt", 0644, NULL, NULL, &sched_dynamic_fops); + return 0; +} +late_initcall(sched_init_debug_dynamic); + +#endif /* CONFIG_SCHED_DEBUG */ +#endif /* CONFIG_PREEMPT_DYNAMIC */ + + /* * This is the entry point to schedule() from kernel preemption * off of irq context. @@ -5616,8 +5808,12 @@ SYSCALL_DEFINE1(nice, int, increment) * @p: the task in question. * * Return: The priority value as seen by users in /proc. - * RT tasks are offset by -200. Normal tasks are centered - * around 0, value goes from -16 to +15. + * + * sched policy return value kernel prio user prio/nice + * + * normal, batch, idle [0 ... 39] [100 ... 139] 0/[-20 ... 19] + * fifo, rr [-2 ... -100] [98 ... 0] [1 ... 99] + * deadline -101 -1 0 */ int task_prio(const struct task_struct *p) { @@ -5676,6 +5872,120 @@ struct task_struct *idle_task(int cpu) return cpu_rq(cpu)->idle; } +#ifdef CONFIG_SMP +/* + * This function computes an effective utilization for the given CPU, to be + * used for frequency selection given the linear relation: f = u * f_max. + * + * The scheduler tracks the following metrics: + * + * cpu_util_{cfs,rt,dl,irq}() + * cpu_bw_dl() + * + * Where the cfs,rt and dl util numbers are tracked with the same metric and + * synchronized windows and are thus directly comparable. + * + * The cfs,rt,dl utilization are the running times measured with rq->clock_task + * which excludes things like IRQ and steal-time. These latter are then accrued + * in the irq utilization. + * + * The DL bandwidth number otoh is not a measured metric but a value computed + * based on the task model parameters and gives the minimal utilization + * required to meet deadlines. + */ +unsigned long effective_cpu_util(int cpu, unsigned long util_cfs, + unsigned long max, enum cpu_util_type type, + struct task_struct *p) +{ + unsigned long dl_util, util, irq; + struct rq *rq = cpu_rq(cpu); + + if (!uclamp_is_used() && + type == FREQUENCY_UTIL && rt_rq_is_runnable(&rq->rt)) { + return max; + } + + /* + * Early check to see if IRQ/steal time saturates the CPU, can be + * because of inaccuracies in how we track these -- see + * update_irq_load_avg(). + */ + irq = cpu_util_irq(rq); + if (unlikely(irq >= max)) + return max; + + /* + * Because the time spend on RT/DL tasks is visible as 'lost' time to + * CFS tasks and we use the same metric to track the effective + * utilization (PELT windows are synchronized) we can directly add them + * to obtain the CPU's actual utilization. + * + * CFS and RT utilization can be boosted or capped, depending on + * utilization clamp constraints requested by currently RUNNABLE + * tasks. + * When there are no CFS RUNNABLE tasks, clamps are released and + * frequency will be gracefully reduced with the utilization decay. + */ + util = util_cfs + cpu_util_rt(rq); + if (type == FREQUENCY_UTIL) + util = uclamp_rq_util_with(rq, util, p); + + dl_util = cpu_util_dl(rq); + + /* + * For frequency selection we do not make cpu_util_dl() a permanent part + * of this sum because we want to use cpu_bw_dl() later on, but we need + * to check if the CFS+RT+DL sum is saturated (ie. no idle time) such + * that we select f_max when there is no idle time. + * + * NOTE: numerical errors or stop class might cause us to not quite hit + * saturation when we should -- something for later. + */ + if (util + dl_util >= max) + return max; + + /* + * OTOH, for energy computation we need the estimated running time, so + * include util_dl and ignore dl_bw. + */ + if (type == ENERGY_UTIL) + util += dl_util; + + /* + * There is still idle time; further improve the number by using the + * irq metric. Because IRQ/steal time is hidden from the task clock we + * need to scale the task numbers: + * + * max - irq + * U' = irq + --------- * U + * max + */ + util = scale_irq_capacity(util, irq, max); + util += irq; + + /* + * Bandwidth required by DEADLINE must always be granted while, for + * FAIR and RT, we use blocked utilization of IDLE CPUs as a mechanism + * to gracefully reduce the frequency when no tasks show up for longer + * periods of time. + * + * Ideally we would like to set bw_dl as min/guaranteed freq and util + + * bw_dl as requested freq. However, cpufreq is not yet ready for such + * an interface. So, we only do the latter for now. + */ + if (type == FREQUENCY_UTIL) + util += cpu_bw_dl(rq); + + return min(max, util); +} + +unsigned long sched_cpu_util(int cpu, unsigned long max) +{ + return effective_cpu_util(cpu, cpu_util_cfs(cpu_rq(cpu)), max, + ENERGY_UTIL, NULL); +} +#endif /* CONFIG_SMP */ + /** * find_process_by_pid - find a process with a matching PID value. * @pid: the pid in question. @@ -5797,11 +6107,10 @@ recheck: /* * Valid priorities for SCHED_FIFO and SCHED_RR are - * 1..MAX_USER_RT_PRIO-1, valid priority for SCHED_NORMAL, + * 1..MAX_RT_PRIO-1, valid priority for SCHED_NORMAL, * SCHED_BATCH and SCHED_IDLE is 0. */ - if ((p->mm && attr->sched_priority > MAX_USER_RT_PRIO-1) || - (!p->mm && attr->sched_priority > MAX_RT_PRIO-1)) + if (attr->sched_priority > MAX_RT_PRIO-1) return -EINVAL; if ((dl_policy(policy) && !__checkparam_dl(attr)) || (rt_policy(policy) != (attr->sched_priority != 0))) @@ -6668,17 +6977,27 @@ SYSCALL_DEFINE0(sched_yield) return 0; } -#ifndef CONFIG_PREEMPTION -int __sched _cond_resched(void) +#if !defined(CONFIG_PREEMPTION) || defined(CONFIG_PREEMPT_DYNAMIC) +int __sched __cond_resched(void) { if (should_resched(0)) { preempt_schedule_common(); return 1; } +#ifndef CONFIG_PREEMPT_RCU rcu_all_qs(); +#endif return 0; } -EXPORT_SYMBOL(_cond_resched); +EXPORT_SYMBOL(__cond_resched); +#endif + +#ifdef CONFIG_PREEMPT_DYNAMIC +DEFINE_STATIC_CALL_RET0(cond_resched, __cond_resched); +EXPORT_STATIC_CALL_TRAMP(cond_resched); + +DEFINE_STATIC_CALL_RET0(might_resched, __cond_resched); +EXPORT_STATIC_CALL_TRAMP(might_resched); #endif /* @@ -6709,6 +7028,46 @@ int __cond_resched_lock(spinlock_t *lock) } EXPORT_SYMBOL(__cond_resched_lock); +int __cond_resched_rwlock_read(rwlock_t *lock) +{ + int resched = should_resched(PREEMPT_LOCK_OFFSET); + int ret = 0; + + lockdep_assert_held_read(lock); + + if (rwlock_needbreak(lock) || resched) { + read_unlock(lock); + if (resched) + preempt_schedule_common(); + else + cpu_relax(); + ret = 1; + read_lock(lock); + } + return ret; +} +EXPORT_SYMBOL(__cond_resched_rwlock_read); + +int __cond_resched_rwlock_write(rwlock_t *lock) +{ + int resched = should_resched(PREEMPT_LOCK_OFFSET); + int ret = 0; + + lockdep_assert_held_write(lock); + + if (rwlock_needbreak(lock) || resched) { + write_unlock(lock); + if (resched) + preempt_schedule_common(); + else + cpu_relax(); + ret = 1; + write_lock(lock); + } + return ret; +} +EXPORT_SYMBOL(__cond_resched_rwlock_write); + /** * yield - yield the current processor to other threads. * @@ -6869,7 +7228,7 @@ SYSCALL_DEFINE1(sched_get_priority_max, int, policy) switch (policy) { case SCHED_FIFO: case SCHED_RR: - ret = MAX_USER_RT_PRIO-1; + ret = MAX_RT_PRIO-1; break; case SCHED_DEADLINE: case SCHED_NORMAL: @@ -7509,6 +7868,12 @@ int sched_cpu_deactivate(unsigned int cpu) struct rq_flags rf; int ret; + /* + * Remove CPU from nohz.idle_cpus_mask to prevent participating in + * load balancing when not active + */ + nohz_balance_exit_idle(rq); + set_cpu_active(cpu, false); /* @@ -7653,7 +8018,6 @@ int sched_cpu_dying(unsigned int cpu) calc_load_migrate(rq); update_max_interval(); - nohz_balance_exit_idle(rq); hrtick_clear(rq); return 0; } |