![Paul E. McKenney](/assets/img/avatar_default.png)
[ Upstream commit 2fe2582649
]
The rcutorture test suite occasionally provokes a splat due to invoking
rt_mutex_lock() which needs to boost the priority of a task currently
sitting on a runqueue that belongs to an offline CPU:
WARNING: CPU: 0 PID: 12 at /home/paulmck/public_git/linux-rcu/arch/x86/kernel/smp.c:128 native_smp_send_reschedule+0x37/0x40
Modules linked in:
CPU: 0 PID: 12 Comm: rcub/7 Not tainted 4.14.0-rc4+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
task: ffff9ed3de5f8cc0 task.stack: ffffbbf80012c000
RIP: 0010:native_smp_send_reschedule+0x37/0x40
RSP: 0018:ffffbbf80012fd10 EFLAGS: 00010082
RAX: 000000000000002f RBX: ffff9ed3dd9cb300 RCX: 0000000000000004
RDX: 0000000080000004 RSI: 0000000000000086 RDI: 00000000ffffffff
RBP: ffffbbf80012fd10 R08: 000000000009da7a R09: 0000000000007b9d
R10: 0000000000000001 R11: ffffffffbb57c2cd R12: 000000000000000d
R13: ffff9ed3de5f8cc0 R14: 0000000000000061 R15: ffff9ed3ded59200
FS: 0000000000000000(0000) GS:ffff9ed3dea00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000080686f0 CR3: 000000001b9e0000 CR4: 00000000000006f0
Call Trace:
resched_curr+0x61/0xd0
switched_to_rt+0x8f/0xa0
rt_mutex_setprio+0x25c/0x410
task_blocks_on_rt_mutex+0x1b3/0x1f0
rt_mutex_slowlock+0xa9/0x1e0
rt_mutex_lock+0x29/0x30
rcu_boost_kthread+0x127/0x3c0
kthread+0x104/0x140
? rcu_report_unblock_qs_rnp+0x90/0x90
? kthread_create_on_node+0x40/0x40
ret_from_fork+0x22/0x30
Code: f0 00 0f 92 c0 84 c0 74 14 48 8b 05 34 74 c5 00 be fd 00 00 00 ff 90 a0 00 00 00 5d c3 89 fe 48 c7 c7 a0 c6 fc b9 e8 d5 b5 06 00 <0f> ff 5d c3 0f 1f 44 00 00 8b 05 a2 d1 13 02 85 c0 75 38 55 48
But the target task's priority has already been adjusted, so the only
purpose of switched_to_rt() invoking resched_curr() is to wake up the
CPU running some task that needs to be preempted by the boosted task.
But the CPU is offline, which presumably means that the task must be
migrated to some other CPU, and that this other CPU will undertake any
needed preemption at the time of migration. Because the runqueue lock
is held when resched_curr() is invoked, we know that the boosted task
cannot go anywhere, so it is not necessary to invoke resched_curr()
in this particular case.
This commit therefore makes switched_to_rt() refrain from invoking
resched_curr() when the target CPU is offline.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2703 lines
63 KiB
C
2703 lines
63 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Real-Time Scheduling Class (mapped to the SCHED_FIFO and SCHED_RR
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* policies)
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*/
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#include "sched.h"
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#include <linux/slab.h>
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#include <linux/irq_work.h>
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int sched_rr_timeslice = RR_TIMESLICE;
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int sysctl_sched_rr_timeslice = (MSEC_PER_SEC / HZ) * RR_TIMESLICE;
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static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun);
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struct rt_bandwidth def_rt_bandwidth;
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static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer)
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{
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struct rt_bandwidth *rt_b =
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container_of(timer, struct rt_bandwidth, rt_period_timer);
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int idle = 0;
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int overrun;
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raw_spin_lock(&rt_b->rt_runtime_lock);
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for (;;) {
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overrun = hrtimer_forward_now(timer, rt_b->rt_period);
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if (!overrun)
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break;
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raw_spin_unlock(&rt_b->rt_runtime_lock);
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idle = do_sched_rt_period_timer(rt_b, overrun);
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raw_spin_lock(&rt_b->rt_runtime_lock);
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}
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if (idle)
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rt_b->rt_period_active = 0;
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raw_spin_unlock(&rt_b->rt_runtime_lock);
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return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
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}
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void init_rt_bandwidth(struct rt_bandwidth *rt_b, u64 period, u64 runtime)
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{
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rt_b->rt_period = ns_to_ktime(period);
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rt_b->rt_runtime = runtime;
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raw_spin_lock_init(&rt_b->rt_runtime_lock);
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hrtimer_init(&rt_b->rt_period_timer,
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CLOCK_MONOTONIC, HRTIMER_MODE_REL);
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rt_b->rt_period_timer.function = sched_rt_period_timer;
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}
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static void start_rt_bandwidth(struct rt_bandwidth *rt_b)
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{
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if (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF)
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return;
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raw_spin_lock(&rt_b->rt_runtime_lock);
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if (!rt_b->rt_period_active) {
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rt_b->rt_period_active = 1;
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/*
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* SCHED_DEADLINE updates the bandwidth, as a run away
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* RT task with a DL task could hog a CPU. But DL does
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* not reset the period. If a deadline task was running
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* without an RT task running, it can cause RT tasks to
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* throttle when they start up. Kick the timer right away
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* to update the period.
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*/
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hrtimer_forward_now(&rt_b->rt_period_timer, ns_to_ktime(0));
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hrtimer_start_expires(&rt_b->rt_period_timer, HRTIMER_MODE_ABS_PINNED);
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}
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raw_spin_unlock(&rt_b->rt_runtime_lock);
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}
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void init_rt_rq(struct rt_rq *rt_rq)
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{
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struct rt_prio_array *array;
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int i;
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array = &rt_rq->active;
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for (i = 0; i < MAX_RT_PRIO; i++) {
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INIT_LIST_HEAD(array->queue + i);
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__clear_bit(i, array->bitmap);
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}
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/* delimiter for bitsearch: */
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__set_bit(MAX_RT_PRIO, array->bitmap);
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#if defined CONFIG_SMP
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rt_rq->highest_prio.curr = MAX_RT_PRIO;
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rt_rq->highest_prio.next = MAX_RT_PRIO;
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rt_rq->rt_nr_migratory = 0;
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rt_rq->overloaded = 0;
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plist_head_init(&rt_rq->pushable_tasks);
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#endif /* CONFIG_SMP */
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/* We start is dequeued state, because no RT tasks are queued */
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rt_rq->rt_queued = 0;
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rt_rq->rt_time = 0;
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rt_rq->rt_throttled = 0;
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rt_rq->rt_runtime = 0;
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raw_spin_lock_init(&rt_rq->rt_runtime_lock);
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}
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#ifdef CONFIG_RT_GROUP_SCHED
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static void destroy_rt_bandwidth(struct rt_bandwidth *rt_b)
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{
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hrtimer_cancel(&rt_b->rt_period_timer);
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}
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#define rt_entity_is_task(rt_se) (!(rt_se)->my_q)
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static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
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{
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#ifdef CONFIG_SCHED_DEBUG
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WARN_ON_ONCE(!rt_entity_is_task(rt_se));
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#endif
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return container_of(rt_se, struct task_struct, rt);
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}
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static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
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{
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return rt_rq->rq;
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}
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static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
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{
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return rt_se->rt_rq;
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}
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static inline struct rq *rq_of_rt_se(struct sched_rt_entity *rt_se)
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{
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struct rt_rq *rt_rq = rt_se->rt_rq;
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return rt_rq->rq;
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}
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void free_rt_sched_group(struct task_group *tg)
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{
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int i;
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if (tg->rt_se)
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destroy_rt_bandwidth(&tg->rt_bandwidth);
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for_each_possible_cpu(i) {
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if (tg->rt_rq)
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kfree(tg->rt_rq[i]);
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if (tg->rt_se)
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kfree(tg->rt_se[i]);
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}
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kfree(tg->rt_rq);
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kfree(tg->rt_se);
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}
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void init_tg_rt_entry(struct task_group *tg, struct rt_rq *rt_rq,
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struct sched_rt_entity *rt_se, int cpu,
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struct sched_rt_entity *parent)
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{
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struct rq *rq = cpu_rq(cpu);
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rt_rq->highest_prio.curr = MAX_RT_PRIO;
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rt_rq->rt_nr_boosted = 0;
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rt_rq->rq = rq;
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rt_rq->tg = tg;
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tg->rt_rq[cpu] = rt_rq;
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tg->rt_se[cpu] = rt_se;
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if (!rt_se)
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return;
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if (!parent)
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rt_se->rt_rq = &rq->rt;
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else
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rt_se->rt_rq = parent->my_q;
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rt_se->my_q = rt_rq;
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rt_se->parent = parent;
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INIT_LIST_HEAD(&rt_se->run_list);
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}
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int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
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{
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struct rt_rq *rt_rq;
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struct sched_rt_entity *rt_se;
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int i;
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tg->rt_rq = kzalloc(sizeof(rt_rq) * nr_cpu_ids, GFP_KERNEL);
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if (!tg->rt_rq)
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goto err;
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tg->rt_se = kzalloc(sizeof(rt_se) * nr_cpu_ids, GFP_KERNEL);
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if (!tg->rt_se)
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goto err;
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init_rt_bandwidth(&tg->rt_bandwidth,
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ktime_to_ns(def_rt_bandwidth.rt_period), 0);
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for_each_possible_cpu(i) {
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rt_rq = kzalloc_node(sizeof(struct rt_rq),
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GFP_KERNEL, cpu_to_node(i));
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if (!rt_rq)
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goto err;
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rt_se = kzalloc_node(sizeof(struct sched_rt_entity),
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GFP_KERNEL, cpu_to_node(i));
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if (!rt_se)
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goto err_free_rq;
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init_rt_rq(rt_rq);
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rt_rq->rt_runtime = tg->rt_bandwidth.rt_runtime;
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init_tg_rt_entry(tg, rt_rq, rt_se, i, parent->rt_se[i]);
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}
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return 1;
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err_free_rq:
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kfree(rt_rq);
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err:
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return 0;
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}
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#else /* CONFIG_RT_GROUP_SCHED */
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#define rt_entity_is_task(rt_se) (1)
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static inline struct task_struct *rt_task_of(struct sched_rt_entity *rt_se)
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{
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return container_of(rt_se, struct task_struct, rt);
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}
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static inline struct rq *rq_of_rt_rq(struct rt_rq *rt_rq)
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{
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return container_of(rt_rq, struct rq, rt);
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}
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static inline struct rq *rq_of_rt_se(struct sched_rt_entity *rt_se)
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{
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struct task_struct *p = rt_task_of(rt_se);
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return task_rq(p);
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}
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static inline struct rt_rq *rt_rq_of_se(struct sched_rt_entity *rt_se)
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{
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struct rq *rq = rq_of_rt_se(rt_se);
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return &rq->rt;
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}
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void free_rt_sched_group(struct task_group *tg) { }
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int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
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{
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return 1;
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}
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#endif /* CONFIG_RT_GROUP_SCHED */
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#ifdef CONFIG_SMP
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static void pull_rt_task(struct rq *this_rq);
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static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev)
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{
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/* Try to pull RT tasks here if we lower this rq's prio */
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return rq->rt.highest_prio.curr > prev->prio;
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}
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static inline int rt_overloaded(struct rq *rq)
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{
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return atomic_read(&rq->rd->rto_count);
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}
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static inline void rt_set_overload(struct rq *rq)
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{
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if (!rq->online)
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return;
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cpumask_set_cpu(rq->cpu, rq->rd->rto_mask);
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/*
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* Make sure the mask is visible before we set
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* the overload count. That is checked to determine
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* if we should look at the mask. It would be a shame
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* if we looked at the mask, but the mask was not
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* updated yet.
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*
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* Matched by the barrier in pull_rt_task().
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*/
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smp_wmb();
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atomic_inc(&rq->rd->rto_count);
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}
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static inline void rt_clear_overload(struct rq *rq)
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{
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if (!rq->online)
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return;
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/* the order here really doesn't matter */
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atomic_dec(&rq->rd->rto_count);
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cpumask_clear_cpu(rq->cpu, rq->rd->rto_mask);
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}
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static void update_rt_migration(struct rt_rq *rt_rq)
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{
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if (rt_rq->rt_nr_migratory && rt_rq->rt_nr_total > 1) {
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if (!rt_rq->overloaded) {
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rt_set_overload(rq_of_rt_rq(rt_rq));
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rt_rq->overloaded = 1;
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}
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} else if (rt_rq->overloaded) {
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rt_clear_overload(rq_of_rt_rq(rt_rq));
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rt_rq->overloaded = 0;
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}
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}
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static void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
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{
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struct task_struct *p;
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if (!rt_entity_is_task(rt_se))
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return;
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p = rt_task_of(rt_se);
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rt_rq = &rq_of_rt_rq(rt_rq)->rt;
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rt_rq->rt_nr_total++;
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if (p->nr_cpus_allowed > 1)
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rt_rq->rt_nr_migratory++;
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update_rt_migration(rt_rq);
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}
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static void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
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{
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struct task_struct *p;
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if (!rt_entity_is_task(rt_se))
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return;
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p = rt_task_of(rt_se);
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rt_rq = &rq_of_rt_rq(rt_rq)->rt;
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rt_rq->rt_nr_total--;
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if (p->nr_cpus_allowed > 1)
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rt_rq->rt_nr_migratory--;
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update_rt_migration(rt_rq);
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}
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static inline int has_pushable_tasks(struct rq *rq)
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{
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return !plist_head_empty(&rq->rt.pushable_tasks);
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}
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static DEFINE_PER_CPU(struct callback_head, rt_push_head);
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static DEFINE_PER_CPU(struct callback_head, rt_pull_head);
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static void push_rt_tasks(struct rq *);
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static void pull_rt_task(struct rq *);
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static inline void queue_push_tasks(struct rq *rq)
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{
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if (!has_pushable_tasks(rq))
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return;
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queue_balance_callback(rq, &per_cpu(rt_push_head, rq->cpu), push_rt_tasks);
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}
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static inline void queue_pull_task(struct rq *rq)
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{
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queue_balance_callback(rq, &per_cpu(rt_pull_head, rq->cpu), pull_rt_task);
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}
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static void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
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{
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plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
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plist_node_init(&p->pushable_tasks, p->prio);
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plist_add(&p->pushable_tasks, &rq->rt.pushable_tasks);
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/* Update the highest prio pushable task */
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if (p->prio < rq->rt.highest_prio.next)
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rq->rt.highest_prio.next = p->prio;
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}
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static void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
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{
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plist_del(&p->pushable_tasks, &rq->rt.pushable_tasks);
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/* Update the new highest prio pushable task */
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if (has_pushable_tasks(rq)) {
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p = plist_first_entry(&rq->rt.pushable_tasks,
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struct task_struct, pushable_tasks);
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rq->rt.highest_prio.next = p->prio;
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} else
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rq->rt.highest_prio.next = MAX_RT_PRIO;
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}
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#else
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static inline void enqueue_pushable_task(struct rq *rq, struct task_struct *p)
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{
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}
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static inline void dequeue_pushable_task(struct rq *rq, struct task_struct *p)
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{
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}
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|
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static inline
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void inc_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
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{
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}
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|
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static inline
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void dec_rt_migration(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
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{
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}
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|
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static inline bool need_pull_rt_task(struct rq *rq, struct task_struct *prev)
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{
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return false;
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}
|
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|
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static inline void pull_rt_task(struct rq *this_rq)
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{
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}
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|
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static inline void queue_push_tasks(struct rq *rq)
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{
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}
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#endif /* CONFIG_SMP */
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|
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static void enqueue_top_rt_rq(struct rt_rq *rt_rq);
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static void dequeue_top_rt_rq(struct rt_rq *rt_rq);
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|
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static inline int on_rt_rq(struct sched_rt_entity *rt_se)
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{
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return rt_se->on_rq;
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}
|
|
|
|
#ifdef CONFIG_RT_GROUP_SCHED
|
|
|
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static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
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|
{
|
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if (!rt_rq->tg)
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return RUNTIME_INF;
|
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|
|
return rt_rq->rt_runtime;
|
|
}
|
|
|
|
static inline u64 sched_rt_period(struct rt_rq *rt_rq)
|
|
{
|
|
return ktime_to_ns(rt_rq->tg->rt_bandwidth.rt_period);
|
|
}
|
|
|
|
typedef struct task_group *rt_rq_iter_t;
|
|
|
|
static inline struct task_group *next_task_group(struct task_group *tg)
|
|
{
|
|
do {
|
|
tg = list_entry_rcu(tg->list.next,
|
|
typeof(struct task_group), list);
|
|
} while (&tg->list != &task_groups && task_group_is_autogroup(tg));
|
|
|
|
if (&tg->list == &task_groups)
|
|
tg = NULL;
|
|
|
|
return tg;
|
|
}
|
|
|
|
#define for_each_rt_rq(rt_rq, iter, rq) \
|
|
for (iter = container_of(&task_groups, typeof(*iter), list); \
|
|
(iter = next_task_group(iter)) && \
|
|
(rt_rq = iter->rt_rq[cpu_of(rq)]);)
|
|
|
|
#define for_each_sched_rt_entity(rt_se) \
|
|
for (; rt_se; rt_se = rt_se->parent)
|
|
|
|
static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
|
|
{
|
|
return rt_se->my_q;
|
|
}
|
|
|
|
static void enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags);
|
|
static void dequeue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags);
|
|
|
|
static void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
|
|
{
|
|
struct task_struct *curr = rq_of_rt_rq(rt_rq)->curr;
|
|
struct rq *rq = rq_of_rt_rq(rt_rq);
|
|
struct sched_rt_entity *rt_se;
|
|
|
|
int cpu = cpu_of(rq);
|
|
|
|
rt_se = rt_rq->tg->rt_se[cpu];
|
|
|
|
if (rt_rq->rt_nr_running) {
|
|
if (!rt_se)
|
|
enqueue_top_rt_rq(rt_rq);
|
|
else if (!on_rt_rq(rt_se))
|
|
enqueue_rt_entity(rt_se, 0);
|
|
|
|
if (rt_rq->highest_prio.curr < curr->prio)
|
|
resched_curr(rq);
|
|
}
|
|
}
|
|
|
|
static void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
|
|
{
|
|
struct sched_rt_entity *rt_se;
|
|
int cpu = cpu_of(rq_of_rt_rq(rt_rq));
|
|
|
|
rt_se = rt_rq->tg->rt_se[cpu];
|
|
|
|
if (!rt_se)
|
|
dequeue_top_rt_rq(rt_rq);
|
|
else if (on_rt_rq(rt_se))
|
|
dequeue_rt_entity(rt_se, 0);
|
|
}
|
|
|
|
static inline int rt_rq_throttled(struct rt_rq *rt_rq)
|
|
{
|
|
return rt_rq->rt_throttled && !rt_rq->rt_nr_boosted;
|
|
}
|
|
|
|
static int rt_se_boosted(struct sched_rt_entity *rt_se)
|
|
{
|
|
struct rt_rq *rt_rq = group_rt_rq(rt_se);
|
|
struct task_struct *p;
|
|
|
|
if (rt_rq)
|
|
return !!rt_rq->rt_nr_boosted;
|
|
|
|
p = rt_task_of(rt_se);
|
|
return p->prio != p->normal_prio;
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
static inline const struct cpumask *sched_rt_period_mask(void)
|
|
{
|
|
return this_rq()->rd->span;
|
|
}
|
|
#else
|
|
static inline const struct cpumask *sched_rt_period_mask(void)
|
|
{
|
|
return cpu_online_mask;
|
|
}
|
|
#endif
|
|
|
|
static inline
|
|
struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
|
|
{
|
|
return container_of(rt_b, struct task_group, rt_bandwidth)->rt_rq[cpu];
|
|
}
|
|
|
|
static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
|
|
{
|
|
return &rt_rq->tg->rt_bandwidth;
|
|
}
|
|
|
|
#else /* !CONFIG_RT_GROUP_SCHED */
|
|
|
|
static inline u64 sched_rt_runtime(struct rt_rq *rt_rq)
|
|
{
|
|
return rt_rq->rt_runtime;
|
|
}
|
|
|
|
static inline u64 sched_rt_period(struct rt_rq *rt_rq)
|
|
{
|
|
return ktime_to_ns(def_rt_bandwidth.rt_period);
|
|
}
|
|
|
|
typedef struct rt_rq *rt_rq_iter_t;
|
|
|
|
#define for_each_rt_rq(rt_rq, iter, rq) \
|
|
for ((void) iter, rt_rq = &rq->rt; rt_rq; rt_rq = NULL)
|
|
|
|
#define for_each_sched_rt_entity(rt_se) \
|
|
for (; rt_se; rt_se = NULL)
|
|
|
|
static inline struct rt_rq *group_rt_rq(struct sched_rt_entity *rt_se)
|
|
{
|
|
return NULL;
|
|
}
|
|
|
|
static inline void sched_rt_rq_enqueue(struct rt_rq *rt_rq)
|
|
{
|
|
struct rq *rq = rq_of_rt_rq(rt_rq);
|
|
|
|
if (!rt_rq->rt_nr_running)
|
|
return;
|
|
|
|
enqueue_top_rt_rq(rt_rq);
|
|
resched_curr(rq);
|
|
}
|
|
|
|
static inline void sched_rt_rq_dequeue(struct rt_rq *rt_rq)
|
|
{
|
|
dequeue_top_rt_rq(rt_rq);
|
|
}
|
|
|
|
static inline int rt_rq_throttled(struct rt_rq *rt_rq)
|
|
{
|
|
return rt_rq->rt_throttled;
|
|
}
|
|
|
|
static inline const struct cpumask *sched_rt_period_mask(void)
|
|
{
|
|
return cpu_online_mask;
|
|
}
|
|
|
|
static inline
|
|
struct rt_rq *sched_rt_period_rt_rq(struct rt_bandwidth *rt_b, int cpu)
|
|
{
|
|
return &cpu_rq(cpu)->rt;
|
|
}
|
|
|
|
static inline struct rt_bandwidth *sched_rt_bandwidth(struct rt_rq *rt_rq)
|
|
{
|
|
return &def_rt_bandwidth;
|
|
}
|
|
|
|
#endif /* CONFIG_RT_GROUP_SCHED */
|
|
|
|
bool sched_rt_bandwidth_account(struct rt_rq *rt_rq)
|
|
{
|
|
struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
|
|
|
|
return (hrtimer_active(&rt_b->rt_period_timer) ||
|
|
rt_rq->rt_time < rt_b->rt_runtime);
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
/*
|
|
* We ran out of runtime, see if we can borrow some from our neighbours.
|
|
*/
|
|
static void do_balance_runtime(struct rt_rq *rt_rq)
|
|
{
|
|
struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
|
|
struct root_domain *rd = rq_of_rt_rq(rt_rq)->rd;
|
|
int i, weight;
|
|
u64 rt_period;
|
|
|
|
weight = cpumask_weight(rd->span);
|
|
|
|
raw_spin_lock(&rt_b->rt_runtime_lock);
|
|
rt_period = ktime_to_ns(rt_b->rt_period);
|
|
for_each_cpu(i, rd->span) {
|
|
struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
|
|
s64 diff;
|
|
|
|
if (iter == rt_rq)
|
|
continue;
|
|
|
|
raw_spin_lock(&iter->rt_runtime_lock);
|
|
/*
|
|
* Either all rqs have inf runtime and there's nothing to steal
|
|
* or __disable_runtime() below sets a specific rq to inf to
|
|
* indicate its been disabled and disalow stealing.
|
|
*/
|
|
if (iter->rt_runtime == RUNTIME_INF)
|
|
goto next;
|
|
|
|
/*
|
|
* From runqueues with spare time, take 1/n part of their
|
|
* spare time, but no more than our period.
|
|
*/
|
|
diff = iter->rt_runtime - iter->rt_time;
|
|
if (diff > 0) {
|
|
diff = div_u64((u64)diff, weight);
|
|
if (rt_rq->rt_runtime + diff > rt_period)
|
|
diff = rt_period - rt_rq->rt_runtime;
|
|
iter->rt_runtime -= diff;
|
|
rt_rq->rt_runtime += diff;
|
|
if (rt_rq->rt_runtime == rt_period) {
|
|
raw_spin_unlock(&iter->rt_runtime_lock);
|
|
break;
|
|
}
|
|
}
|
|
next:
|
|
raw_spin_unlock(&iter->rt_runtime_lock);
|
|
}
|
|
raw_spin_unlock(&rt_b->rt_runtime_lock);
|
|
}
|
|
|
|
/*
|
|
* Ensure this RQ takes back all the runtime it lend to its neighbours.
|
|
*/
|
|
static void __disable_runtime(struct rq *rq)
|
|
{
|
|
struct root_domain *rd = rq->rd;
|
|
rt_rq_iter_t iter;
|
|
struct rt_rq *rt_rq;
|
|
|
|
if (unlikely(!scheduler_running))
|
|
return;
|
|
|
|
for_each_rt_rq(rt_rq, iter, rq) {
|
|
struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
|
|
s64 want;
|
|
int i;
|
|
|
|
raw_spin_lock(&rt_b->rt_runtime_lock);
|
|
raw_spin_lock(&rt_rq->rt_runtime_lock);
|
|
/*
|
|
* Either we're all inf and nobody needs to borrow, or we're
|
|
* already disabled and thus have nothing to do, or we have
|
|
* exactly the right amount of runtime to take out.
|
|
*/
|
|
if (rt_rq->rt_runtime == RUNTIME_INF ||
|
|
rt_rq->rt_runtime == rt_b->rt_runtime)
|
|
goto balanced;
|
|
raw_spin_unlock(&rt_rq->rt_runtime_lock);
|
|
|
|
/*
|
|
* Calculate the difference between what we started out with
|
|
* and what we current have, that's the amount of runtime
|
|
* we lend and now have to reclaim.
|
|
*/
|
|
want = rt_b->rt_runtime - rt_rq->rt_runtime;
|
|
|
|
/*
|
|
* Greedy reclaim, take back as much as we can.
|
|
*/
|
|
for_each_cpu(i, rd->span) {
|
|
struct rt_rq *iter = sched_rt_period_rt_rq(rt_b, i);
|
|
s64 diff;
|
|
|
|
/*
|
|
* Can't reclaim from ourselves or disabled runqueues.
|
|
*/
|
|
if (iter == rt_rq || iter->rt_runtime == RUNTIME_INF)
|
|
continue;
|
|
|
|
raw_spin_lock(&iter->rt_runtime_lock);
|
|
if (want > 0) {
|
|
diff = min_t(s64, iter->rt_runtime, want);
|
|
iter->rt_runtime -= diff;
|
|
want -= diff;
|
|
} else {
|
|
iter->rt_runtime -= want;
|
|
want -= want;
|
|
}
|
|
raw_spin_unlock(&iter->rt_runtime_lock);
|
|
|
|
if (!want)
|
|
break;
|
|
}
|
|
|
|
raw_spin_lock(&rt_rq->rt_runtime_lock);
|
|
/*
|
|
* We cannot be left wanting - that would mean some runtime
|
|
* leaked out of the system.
|
|
*/
|
|
BUG_ON(want);
|
|
balanced:
|
|
/*
|
|
* Disable all the borrow logic by pretending we have inf
|
|
* runtime - in which case borrowing doesn't make sense.
|
|
*/
|
|
rt_rq->rt_runtime = RUNTIME_INF;
|
|
rt_rq->rt_throttled = 0;
|
|
raw_spin_unlock(&rt_rq->rt_runtime_lock);
|
|
raw_spin_unlock(&rt_b->rt_runtime_lock);
|
|
|
|
/* Make rt_rq available for pick_next_task() */
|
|
sched_rt_rq_enqueue(rt_rq);
|
|
}
|
|
}
|
|
|
|
static void __enable_runtime(struct rq *rq)
|
|
{
|
|
rt_rq_iter_t iter;
|
|
struct rt_rq *rt_rq;
|
|
|
|
if (unlikely(!scheduler_running))
|
|
return;
|
|
|
|
/*
|
|
* Reset each runqueue's bandwidth settings
|
|
*/
|
|
for_each_rt_rq(rt_rq, iter, rq) {
|
|
struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
|
|
|
|
raw_spin_lock(&rt_b->rt_runtime_lock);
|
|
raw_spin_lock(&rt_rq->rt_runtime_lock);
|
|
rt_rq->rt_runtime = rt_b->rt_runtime;
|
|
rt_rq->rt_time = 0;
|
|
rt_rq->rt_throttled = 0;
|
|
raw_spin_unlock(&rt_rq->rt_runtime_lock);
|
|
raw_spin_unlock(&rt_b->rt_runtime_lock);
|
|
}
|
|
}
|
|
|
|
static void balance_runtime(struct rt_rq *rt_rq)
|
|
{
|
|
if (!sched_feat(RT_RUNTIME_SHARE))
|
|
return;
|
|
|
|
if (rt_rq->rt_time > rt_rq->rt_runtime) {
|
|
raw_spin_unlock(&rt_rq->rt_runtime_lock);
|
|
do_balance_runtime(rt_rq);
|
|
raw_spin_lock(&rt_rq->rt_runtime_lock);
|
|
}
|
|
}
|
|
#else /* !CONFIG_SMP */
|
|
static inline void balance_runtime(struct rt_rq *rt_rq) {}
|
|
#endif /* CONFIG_SMP */
|
|
|
|
static int do_sched_rt_period_timer(struct rt_bandwidth *rt_b, int overrun)
|
|
{
|
|
int i, idle = 1, throttled = 0;
|
|
const struct cpumask *span;
|
|
|
|
span = sched_rt_period_mask();
|
|
#ifdef CONFIG_RT_GROUP_SCHED
|
|
/*
|
|
* FIXME: isolated CPUs should really leave the root task group,
|
|
* whether they are isolcpus or were isolated via cpusets, lest
|
|
* the timer run on a CPU which does not service all runqueues,
|
|
* potentially leaving other CPUs indefinitely throttled. If
|
|
* isolation is really required, the user will turn the throttle
|
|
* off to kill the perturbations it causes anyway. Meanwhile,
|
|
* this maintains functionality for boot and/or troubleshooting.
|
|
*/
|
|
if (rt_b == &root_task_group.rt_bandwidth)
|
|
span = cpu_online_mask;
|
|
#endif
|
|
for_each_cpu(i, span) {
|
|
int enqueue = 0;
|
|
struct rt_rq *rt_rq = sched_rt_period_rt_rq(rt_b, i);
|
|
struct rq *rq = rq_of_rt_rq(rt_rq);
|
|
int skip;
|
|
|
|
/*
|
|
* When span == cpu_online_mask, taking each rq->lock
|
|
* can be time-consuming. Try to avoid it when possible.
|
|
*/
|
|
raw_spin_lock(&rt_rq->rt_runtime_lock);
|
|
skip = !rt_rq->rt_time && !rt_rq->rt_nr_running;
|
|
raw_spin_unlock(&rt_rq->rt_runtime_lock);
|
|
if (skip)
|
|
continue;
|
|
|
|
raw_spin_lock(&rq->lock);
|
|
if (rt_rq->rt_time) {
|
|
u64 runtime;
|
|
|
|
raw_spin_lock(&rt_rq->rt_runtime_lock);
|
|
if (rt_rq->rt_throttled)
|
|
balance_runtime(rt_rq);
|
|
runtime = rt_rq->rt_runtime;
|
|
rt_rq->rt_time -= min(rt_rq->rt_time, overrun*runtime);
|
|
if (rt_rq->rt_throttled && rt_rq->rt_time < runtime) {
|
|
rt_rq->rt_throttled = 0;
|
|
enqueue = 1;
|
|
|
|
/*
|
|
* When we're idle and a woken (rt) task is
|
|
* throttled check_preempt_curr() will set
|
|
* skip_update and the time between the wakeup
|
|
* and this unthrottle will get accounted as
|
|
* 'runtime'.
|
|
*/
|
|
if (rt_rq->rt_nr_running && rq->curr == rq->idle)
|
|
rq_clock_skip_update(rq, false);
|
|
}
|
|
if (rt_rq->rt_time || rt_rq->rt_nr_running)
|
|
idle = 0;
|
|
raw_spin_unlock(&rt_rq->rt_runtime_lock);
|
|
} else if (rt_rq->rt_nr_running) {
|
|
idle = 0;
|
|
if (!rt_rq_throttled(rt_rq))
|
|
enqueue = 1;
|
|
}
|
|
if (rt_rq->rt_throttled)
|
|
throttled = 1;
|
|
|
|
if (enqueue)
|
|
sched_rt_rq_enqueue(rt_rq);
|
|
raw_spin_unlock(&rq->lock);
|
|
}
|
|
|
|
if (!throttled && (!rt_bandwidth_enabled() || rt_b->rt_runtime == RUNTIME_INF))
|
|
return 1;
|
|
|
|
return idle;
|
|
}
|
|
|
|
static inline int rt_se_prio(struct sched_rt_entity *rt_se)
|
|
{
|
|
#ifdef CONFIG_RT_GROUP_SCHED
|
|
struct rt_rq *rt_rq = group_rt_rq(rt_se);
|
|
|
|
if (rt_rq)
|
|
return rt_rq->highest_prio.curr;
|
|
#endif
|
|
|
|
return rt_task_of(rt_se)->prio;
|
|
}
|
|
|
|
static int sched_rt_runtime_exceeded(struct rt_rq *rt_rq)
|
|
{
|
|
u64 runtime = sched_rt_runtime(rt_rq);
|
|
|
|
if (rt_rq->rt_throttled)
|
|
return rt_rq_throttled(rt_rq);
|
|
|
|
if (runtime >= sched_rt_period(rt_rq))
|
|
return 0;
|
|
|
|
balance_runtime(rt_rq);
|
|
runtime = sched_rt_runtime(rt_rq);
|
|
if (runtime == RUNTIME_INF)
|
|
return 0;
|
|
|
|
if (rt_rq->rt_time > runtime) {
|
|
struct rt_bandwidth *rt_b = sched_rt_bandwidth(rt_rq);
|
|
|
|
/*
|
|
* Don't actually throttle groups that have no runtime assigned
|
|
* but accrue some time due to boosting.
|
|
*/
|
|
if (likely(rt_b->rt_runtime)) {
|
|
rt_rq->rt_throttled = 1;
|
|
printk_deferred_once("sched: RT throttling activated\n");
|
|
} else {
|
|
/*
|
|
* In case we did anyway, make it go away,
|
|
* replenishment is a joke, since it will replenish us
|
|
* with exactly 0 ns.
|
|
*/
|
|
rt_rq->rt_time = 0;
|
|
}
|
|
|
|
if (rt_rq_throttled(rt_rq)) {
|
|
sched_rt_rq_dequeue(rt_rq);
|
|
return 1;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Update the current task's runtime statistics. Skip current tasks that
|
|
* are not in our scheduling class.
|
|
*/
|
|
static void update_curr_rt(struct rq *rq)
|
|
{
|
|
struct task_struct *curr = rq->curr;
|
|
struct sched_rt_entity *rt_se = &curr->rt;
|
|
u64 delta_exec;
|
|
|
|
if (curr->sched_class != &rt_sched_class)
|
|
return;
|
|
|
|
delta_exec = rq_clock_task(rq) - curr->se.exec_start;
|
|
if (unlikely((s64)delta_exec <= 0))
|
|
return;
|
|
|
|
/* Kick cpufreq (see the comment in kernel/sched/sched.h). */
|
|
cpufreq_update_util(rq, SCHED_CPUFREQ_RT);
|
|
|
|
schedstat_set(curr->se.statistics.exec_max,
|
|
max(curr->se.statistics.exec_max, delta_exec));
|
|
|
|
curr->se.sum_exec_runtime += delta_exec;
|
|
account_group_exec_runtime(curr, delta_exec);
|
|
|
|
curr->se.exec_start = rq_clock_task(rq);
|
|
cpuacct_charge(curr, delta_exec);
|
|
|
|
sched_rt_avg_update(rq, delta_exec);
|
|
|
|
if (!rt_bandwidth_enabled())
|
|
return;
|
|
|
|
for_each_sched_rt_entity(rt_se) {
|
|
struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
|
|
|
|
if (sched_rt_runtime(rt_rq) != RUNTIME_INF) {
|
|
raw_spin_lock(&rt_rq->rt_runtime_lock);
|
|
rt_rq->rt_time += delta_exec;
|
|
if (sched_rt_runtime_exceeded(rt_rq))
|
|
resched_curr(rq);
|
|
raw_spin_unlock(&rt_rq->rt_runtime_lock);
|
|
}
|
|
}
|
|
}
|
|
|
|
static void
|
|
dequeue_top_rt_rq(struct rt_rq *rt_rq)
|
|
{
|
|
struct rq *rq = rq_of_rt_rq(rt_rq);
|
|
|
|
BUG_ON(&rq->rt != rt_rq);
|
|
|
|
if (!rt_rq->rt_queued)
|
|
return;
|
|
|
|
BUG_ON(!rq->nr_running);
|
|
|
|
sub_nr_running(rq, rt_rq->rt_nr_running);
|
|
rt_rq->rt_queued = 0;
|
|
}
|
|
|
|
static void
|
|
enqueue_top_rt_rq(struct rt_rq *rt_rq)
|
|
{
|
|
struct rq *rq = rq_of_rt_rq(rt_rq);
|
|
|
|
BUG_ON(&rq->rt != rt_rq);
|
|
|
|
if (rt_rq->rt_queued)
|
|
return;
|
|
if (rt_rq_throttled(rt_rq) || !rt_rq->rt_nr_running)
|
|
return;
|
|
|
|
add_nr_running(rq, rt_rq->rt_nr_running);
|
|
rt_rq->rt_queued = 1;
|
|
}
|
|
|
|
#if defined CONFIG_SMP
|
|
|
|
static void
|
|
inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
|
|
{
|
|
struct rq *rq = rq_of_rt_rq(rt_rq);
|
|
|
|
#ifdef CONFIG_RT_GROUP_SCHED
|
|
/*
|
|
* Change rq's cpupri only if rt_rq is the top queue.
|
|
*/
|
|
if (&rq->rt != rt_rq)
|
|
return;
|
|
#endif
|
|
if (rq->online && prio < prev_prio)
|
|
cpupri_set(&rq->rd->cpupri, rq->cpu, prio);
|
|
}
|
|
|
|
static void
|
|
dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio)
|
|
{
|
|
struct rq *rq = rq_of_rt_rq(rt_rq);
|
|
|
|
#ifdef CONFIG_RT_GROUP_SCHED
|
|
/*
|
|
* Change rq's cpupri only if rt_rq is the top queue.
|
|
*/
|
|
if (&rq->rt != rt_rq)
|
|
return;
|
|
#endif
|
|
if (rq->online && rt_rq->highest_prio.curr != prev_prio)
|
|
cpupri_set(&rq->rd->cpupri, rq->cpu, rt_rq->highest_prio.curr);
|
|
}
|
|
|
|
#else /* CONFIG_SMP */
|
|
|
|
static inline
|
|
void inc_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
|
|
static inline
|
|
void dec_rt_prio_smp(struct rt_rq *rt_rq, int prio, int prev_prio) {}
|
|
|
|
#endif /* CONFIG_SMP */
|
|
|
|
#if defined CONFIG_SMP || defined CONFIG_RT_GROUP_SCHED
|
|
static void
|
|
inc_rt_prio(struct rt_rq *rt_rq, int prio)
|
|
{
|
|
int prev_prio = rt_rq->highest_prio.curr;
|
|
|
|
if (prio < prev_prio)
|
|
rt_rq->highest_prio.curr = prio;
|
|
|
|
inc_rt_prio_smp(rt_rq, prio, prev_prio);
|
|
}
|
|
|
|
static void
|
|
dec_rt_prio(struct rt_rq *rt_rq, int prio)
|
|
{
|
|
int prev_prio = rt_rq->highest_prio.curr;
|
|
|
|
if (rt_rq->rt_nr_running) {
|
|
|
|
WARN_ON(prio < prev_prio);
|
|
|
|
/*
|
|
* This may have been our highest task, and therefore
|
|
* we may have some recomputation to do
|
|
*/
|
|
if (prio == prev_prio) {
|
|
struct rt_prio_array *array = &rt_rq->active;
|
|
|
|
rt_rq->highest_prio.curr =
|
|
sched_find_first_bit(array->bitmap);
|
|
}
|
|
|
|
} else
|
|
rt_rq->highest_prio.curr = MAX_RT_PRIO;
|
|
|
|
dec_rt_prio_smp(rt_rq, prio, prev_prio);
|
|
}
|
|
|
|
#else
|
|
|
|
static inline void inc_rt_prio(struct rt_rq *rt_rq, int prio) {}
|
|
static inline void dec_rt_prio(struct rt_rq *rt_rq, int prio) {}
|
|
|
|
#endif /* CONFIG_SMP || CONFIG_RT_GROUP_SCHED */
|
|
|
|
#ifdef CONFIG_RT_GROUP_SCHED
|
|
|
|
static void
|
|
inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
|
|
{
|
|
if (rt_se_boosted(rt_se))
|
|
rt_rq->rt_nr_boosted++;
|
|
|
|
if (rt_rq->tg)
|
|
start_rt_bandwidth(&rt_rq->tg->rt_bandwidth);
|
|
}
|
|
|
|
static void
|
|
dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
|
|
{
|
|
if (rt_se_boosted(rt_se))
|
|
rt_rq->rt_nr_boosted--;
|
|
|
|
WARN_ON(!rt_rq->rt_nr_running && rt_rq->rt_nr_boosted);
|
|
}
|
|
|
|
#else /* CONFIG_RT_GROUP_SCHED */
|
|
|
|
static void
|
|
inc_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
|
|
{
|
|
start_rt_bandwidth(&def_rt_bandwidth);
|
|
}
|
|
|
|
static inline
|
|
void dec_rt_group(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq) {}
|
|
|
|
#endif /* CONFIG_RT_GROUP_SCHED */
|
|
|
|
static inline
|
|
unsigned int rt_se_nr_running(struct sched_rt_entity *rt_se)
|
|
{
|
|
struct rt_rq *group_rq = group_rt_rq(rt_se);
|
|
|
|
if (group_rq)
|
|
return group_rq->rt_nr_running;
|
|
else
|
|
return 1;
|
|
}
|
|
|
|
static inline
|
|
unsigned int rt_se_rr_nr_running(struct sched_rt_entity *rt_se)
|
|
{
|
|
struct rt_rq *group_rq = group_rt_rq(rt_se);
|
|
struct task_struct *tsk;
|
|
|
|
if (group_rq)
|
|
return group_rq->rr_nr_running;
|
|
|
|
tsk = rt_task_of(rt_se);
|
|
|
|
return (tsk->policy == SCHED_RR) ? 1 : 0;
|
|
}
|
|
|
|
static inline
|
|
void inc_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
|
|
{
|
|
int prio = rt_se_prio(rt_se);
|
|
|
|
WARN_ON(!rt_prio(prio));
|
|
rt_rq->rt_nr_running += rt_se_nr_running(rt_se);
|
|
rt_rq->rr_nr_running += rt_se_rr_nr_running(rt_se);
|
|
|
|
inc_rt_prio(rt_rq, prio);
|
|
inc_rt_migration(rt_se, rt_rq);
|
|
inc_rt_group(rt_se, rt_rq);
|
|
}
|
|
|
|
static inline
|
|
void dec_rt_tasks(struct sched_rt_entity *rt_se, struct rt_rq *rt_rq)
|
|
{
|
|
WARN_ON(!rt_prio(rt_se_prio(rt_se)));
|
|
WARN_ON(!rt_rq->rt_nr_running);
|
|
rt_rq->rt_nr_running -= rt_se_nr_running(rt_se);
|
|
rt_rq->rr_nr_running -= rt_se_rr_nr_running(rt_se);
|
|
|
|
dec_rt_prio(rt_rq, rt_se_prio(rt_se));
|
|
dec_rt_migration(rt_se, rt_rq);
|
|
dec_rt_group(rt_se, rt_rq);
|
|
}
|
|
|
|
/*
|
|
* Change rt_se->run_list location unless SAVE && !MOVE
|
|
*
|
|
* assumes ENQUEUE/DEQUEUE flags match
|
|
*/
|
|
static inline bool move_entity(unsigned int flags)
|
|
{
|
|
if ((flags & (DEQUEUE_SAVE | DEQUEUE_MOVE)) == DEQUEUE_SAVE)
|
|
return false;
|
|
|
|
return true;
|
|
}
|
|
|
|
static void __delist_rt_entity(struct sched_rt_entity *rt_se, struct rt_prio_array *array)
|
|
{
|
|
list_del_init(&rt_se->run_list);
|
|
|
|
if (list_empty(array->queue + rt_se_prio(rt_se)))
|
|
__clear_bit(rt_se_prio(rt_se), array->bitmap);
|
|
|
|
rt_se->on_list = 0;
|
|
}
|
|
|
|
static void __enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
|
|
{
|
|
struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
|
|
struct rt_prio_array *array = &rt_rq->active;
|
|
struct rt_rq *group_rq = group_rt_rq(rt_se);
|
|
struct list_head *queue = array->queue + rt_se_prio(rt_se);
|
|
|
|
/*
|
|
* Don't enqueue the group if its throttled, or when empty.
|
|
* The latter is a consequence of the former when a child group
|
|
* get throttled and the current group doesn't have any other
|
|
* active members.
|
|
*/
|
|
if (group_rq && (rt_rq_throttled(group_rq) || !group_rq->rt_nr_running)) {
|
|
if (rt_se->on_list)
|
|
__delist_rt_entity(rt_se, array);
|
|
return;
|
|
}
|
|
|
|
if (move_entity(flags)) {
|
|
WARN_ON_ONCE(rt_se->on_list);
|
|
if (flags & ENQUEUE_HEAD)
|
|
list_add(&rt_se->run_list, queue);
|
|
else
|
|
list_add_tail(&rt_se->run_list, queue);
|
|
|
|
__set_bit(rt_se_prio(rt_se), array->bitmap);
|
|
rt_se->on_list = 1;
|
|
}
|
|
rt_se->on_rq = 1;
|
|
|
|
inc_rt_tasks(rt_se, rt_rq);
|
|
}
|
|
|
|
static void __dequeue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
|
|
{
|
|
struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
|
|
struct rt_prio_array *array = &rt_rq->active;
|
|
|
|
if (move_entity(flags)) {
|
|
WARN_ON_ONCE(!rt_se->on_list);
|
|
__delist_rt_entity(rt_se, array);
|
|
}
|
|
rt_se->on_rq = 0;
|
|
|
|
dec_rt_tasks(rt_se, rt_rq);
|
|
}
|
|
|
|
/*
|
|
* Because the prio of an upper entry depends on the lower
|
|
* entries, we must remove entries top - down.
|
|
*/
|
|
static void dequeue_rt_stack(struct sched_rt_entity *rt_se, unsigned int flags)
|
|
{
|
|
struct sched_rt_entity *back = NULL;
|
|
|
|
for_each_sched_rt_entity(rt_se) {
|
|
rt_se->back = back;
|
|
back = rt_se;
|
|
}
|
|
|
|
dequeue_top_rt_rq(rt_rq_of_se(back));
|
|
|
|
for (rt_se = back; rt_se; rt_se = rt_se->back) {
|
|
if (on_rt_rq(rt_se))
|
|
__dequeue_rt_entity(rt_se, flags);
|
|
}
|
|
}
|
|
|
|
static void enqueue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
|
|
{
|
|
struct rq *rq = rq_of_rt_se(rt_se);
|
|
|
|
dequeue_rt_stack(rt_se, flags);
|
|
for_each_sched_rt_entity(rt_se)
|
|
__enqueue_rt_entity(rt_se, flags);
|
|
enqueue_top_rt_rq(&rq->rt);
|
|
}
|
|
|
|
static void dequeue_rt_entity(struct sched_rt_entity *rt_se, unsigned int flags)
|
|
{
|
|
struct rq *rq = rq_of_rt_se(rt_se);
|
|
|
|
dequeue_rt_stack(rt_se, flags);
|
|
|
|
for_each_sched_rt_entity(rt_se) {
|
|
struct rt_rq *rt_rq = group_rt_rq(rt_se);
|
|
|
|
if (rt_rq && rt_rq->rt_nr_running)
|
|
__enqueue_rt_entity(rt_se, flags);
|
|
}
|
|
enqueue_top_rt_rq(&rq->rt);
|
|
}
|
|
|
|
/*
|
|
* Adding/removing a task to/from a priority array:
|
|
*/
|
|
static void
|
|
enqueue_task_rt(struct rq *rq, struct task_struct *p, int flags)
|
|
{
|
|
struct sched_rt_entity *rt_se = &p->rt;
|
|
|
|
if (flags & ENQUEUE_WAKEUP)
|
|
rt_se->timeout = 0;
|
|
|
|
enqueue_rt_entity(rt_se, flags);
|
|
|
|
if (!task_current(rq, p) && p->nr_cpus_allowed > 1)
|
|
enqueue_pushable_task(rq, p);
|
|
}
|
|
|
|
static void dequeue_task_rt(struct rq *rq, struct task_struct *p, int flags)
|
|
{
|
|
struct sched_rt_entity *rt_se = &p->rt;
|
|
|
|
update_curr_rt(rq);
|
|
dequeue_rt_entity(rt_se, flags);
|
|
|
|
dequeue_pushable_task(rq, p);
|
|
}
|
|
|
|
/*
|
|
* Put task to the head or the end of the run list without the overhead of
|
|
* dequeue followed by enqueue.
|
|
*/
|
|
static void
|
|
requeue_rt_entity(struct rt_rq *rt_rq, struct sched_rt_entity *rt_se, int head)
|
|
{
|
|
if (on_rt_rq(rt_se)) {
|
|
struct rt_prio_array *array = &rt_rq->active;
|
|
struct list_head *queue = array->queue + rt_se_prio(rt_se);
|
|
|
|
if (head)
|
|
list_move(&rt_se->run_list, queue);
|
|
else
|
|
list_move_tail(&rt_se->run_list, queue);
|
|
}
|
|
}
|
|
|
|
static void requeue_task_rt(struct rq *rq, struct task_struct *p, int head)
|
|
{
|
|
struct sched_rt_entity *rt_se = &p->rt;
|
|
struct rt_rq *rt_rq;
|
|
|
|
for_each_sched_rt_entity(rt_se) {
|
|
rt_rq = rt_rq_of_se(rt_se);
|
|
requeue_rt_entity(rt_rq, rt_se, head);
|
|
}
|
|
}
|
|
|
|
static void yield_task_rt(struct rq *rq)
|
|
{
|
|
requeue_task_rt(rq, rq->curr, 0);
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
static int find_lowest_rq(struct task_struct *task);
|
|
|
|
static int
|
|
select_task_rq_rt(struct task_struct *p, int cpu, int sd_flag, int flags)
|
|
{
|
|
struct task_struct *curr;
|
|
struct rq *rq;
|
|
|
|
/* For anything but wake ups, just return the task_cpu */
|
|
if (sd_flag != SD_BALANCE_WAKE && sd_flag != SD_BALANCE_FORK)
|
|
goto out;
|
|
|
|
rq = cpu_rq(cpu);
|
|
|
|
rcu_read_lock();
|
|
curr = READ_ONCE(rq->curr); /* unlocked access */
|
|
|
|
/*
|
|
* If the current task on @p's runqueue is an RT task, then
|
|
* try to see if we can wake this RT task up on another
|
|
* runqueue. Otherwise simply start this RT task
|
|
* on its current runqueue.
|
|
*
|
|
* We want to avoid overloading runqueues. If the woken
|
|
* task is a higher priority, then it will stay on this CPU
|
|
* and the lower prio task should be moved to another CPU.
|
|
* Even though this will probably make the lower prio task
|
|
* lose its cache, we do not want to bounce a higher task
|
|
* around just because it gave up its CPU, perhaps for a
|
|
* lock?
|
|
*
|
|
* For equal prio tasks, we just let the scheduler sort it out.
|
|
*
|
|
* Otherwise, just let it ride on the affined RQ and the
|
|
* post-schedule router will push the preempted task away
|
|
*
|
|
* This test is optimistic, if we get it wrong the load-balancer
|
|
* will have to sort it out.
|
|
*/
|
|
if (curr && unlikely(rt_task(curr)) &&
|
|
(curr->nr_cpus_allowed < 2 ||
|
|
curr->prio <= p->prio)) {
|
|
int target = find_lowest_rq(p);
|
|
|
|
/*
|
|
* Don't bother moving it if the destination CPU is
|
|
* not running a lower priority task.
|
|
*/
|
|
if (target != -1 &&
|
|
p->prio < cpu_rq(target)->rt.highest_prio.curr)
|
|
cpu = target;
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
out:
|
|
return cpu;
|
|
}
|
|
|
|
static void check_preempt_equal_prio(struct rq *rq, struct task_struct *p)
|
|
{
|
|
/*
|
|
* Current can't be migrated, useless to reschedule,
|
|
* let's hope p can move out.
|
|
*/
|
|
if (rq->curr->nr_cpus_allowed == 1 ||
|
|
!cpupri_find(&rq->rd->cpupri, rq->curr, NULL))
|
|
return;
|
|
|
|
/*
|
|
* p is migratable, so let's not schedule it and
|
|
* see if it is pushed or pulled somewhere else.
|
|
*/
|
|
if (p->nr_cpus_allowed != 1
|
|
&& cpupri_find(&rq->rd->cpupri, p, NULL))
|
|
return;
|
|
|
|
/*
|
|
* There appears to be other cpus that can accept
|
|
* current and none to run 'p', so lets reschedule
|
|
* to try and push current away:
|
|
*/
|
|
requeue_task_rt(rq, p, 1);
|
|
resched_curr(rq);
|
|
}
|
|
|
|
#endif /* CONFIG_SMP */
|
|
|
|
/*
|
|
* Preempt the current task with a newly woken task if needed:
|
|
*/
|
|
static void check_preempt_curr_rt(struct rq *rq, struct task_struct *p, int flags)
|
|
{
|
|
if (p->prio < rq->curr->prio) {
|
|
resched_curr(rq);
|
|
return;
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
/*
|
|
* If:
|
|
*
|
|
* - the newly woken task is of equal priority to the current task
|
|
* - the newly woken task is non-migratable while current is migratable
|
|
* - current will be preempted on the next reschedule
|
|
*
|
|
* we should check to see if current can readily move to a different
|
|
* cpu. If so, we will reschedule to allow the push logic to try
|
|
* to move current somewhere else, making room for our non-migratable
|
|
* task.
|
|
*/
|
|
if (p->prio == rq->curr->prio && !test_tsk_need_resched(rq->curr))
|
|
check_preempt_equal_prio(rq, p);
|
|
#endif
|
|
}
|
|
|
|
static struct sched_rt_entity *pick_next_rt_entity(struct rq *rq,
|
|
struct rt_rq *rt_rq)
|
|
{
|
|
struct rt_prio_array *array = &rt_rq->active;
|
|
struct sched_rt_entity *next = NULL;
|
|
struct list_head *queue;
|
|
int idx;
|
|
|
|
idx = sched_find_first_bit(array->bitmap);
|
|
BUG_ON(idx >= MAX_RT_PRIO);
|
|
|
|
queue = array->queue + idx;
|
|
next = list_entry(queue->next, struct sched_rt_entity, run_list);
|
|
|
|
return next;
|
|
}
|
|
|
|
static struct task_struct *_pick_next_task_rt(struct rq *rq)
|
|
{
|
|
struct sched_rt_entity *rt_se;
|
|
struct task_struct *p;
|
|
struct rt_rq *rt_rq = &rq->rt;
|
|
|
|
do {
|
|
rt_se = pick_next_rt_entity(rq, rt_rq);
|
|
BUG_ON(!rt_se);
|
|
rt_rq = group_rt_rq(rt_se);
|
|
} while (rt_rq);
|
|
|
|
p = rt_task_of(rt_se);
|
|
p->se.exec_start = rq_clock_task(rq);
|
|
|
|
return p;
|
|
}
|
|
|
|
static struct task_struct *
|
|
pick_next_task_rt(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
|
|
{
|
|
struct task_struct *p;
|
|
struct rt_rq *rt_rq = &rq->rt;
|
|
|
|
if (need_pull_rt_task(rq, prev)) {
|
|
/*
|
|
* This is OK, because current is on_cpu, which avoids it being
|
|
* picked for load-balance and preemption/IRQs are still
|
|
* disabled avoiding further scheduler activity on it and we're
|
|
* being very careful to re-start the picking loop.
|
|
*/
|
|
rq_unpin_lock(rq, rf);
|
|
pull_rt_task(rq);
|
|
rq_repin_lock(rq, rf);
|
|
/*
|
|
* pull_rt_task() can drop (and re-acquire) rq->lock; this
|
|
* means a dl or stop task can slip in, in which case we need
|
|
* to re-start task selection.
|
|
*/
|
|
if (unlikely((rq->stop && task_on_rq_queued(rq->stop)) ||
|
|
rq->dl.dl_nr_running))
|
|
return RETRY_TASK;
|
|
}
|
|
|
|
/*
|
|
* We may dequeue prev's rt_rq in put_prev_task().
|
|
* So, we update time before rt_nr_running check.
|
|
*/
|
|
if (prev->sched_class == &rt_sched_class)
|
|
update_curr_rt(rq);
|
|
|
|
if (!rt_rq->rt_queued)
|
|
return NULL;
|
|
|
|
put_prev_task(rq, prev);
|
|
|
|
p = _pick_next_task_rt(rq);
|
|
|
|
/* The running task is never eligible for pushing */
|
|
dequeue_pushable_task(rq, p);
|
|
|
|
queue_push_tasks(rq);
|
|
|
|
return p;
|
|
}
|
|
|
|
static void put_prev_task_rt(struct rq *rq, struct task_struct *p)
|
|
{
|
|
update_curr_rt(rq);
|
|
|
|
/*
|
|
* The previous task needs to be made eligible for pushing
|
|
* if it is still active
|
|
*/
|
|
if (on_rt_rq(&p->rt) && p->nr_cpus_allowed > 1)
|
|
enqueue_pushable_task(rq, p);
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
|
|
/* Only try algorithms three times */
|
|
#define RT_MAX_TRIES 3
|
|
|
|
static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
|
|
{
|
|
if (!task_running(rq, p) &&
|
|
cpumask_test_cpu(cpu, &p->cpus_allowed))
|
|
return 1;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Return the highest pushable rq's task, which is suitable to be executed
|
|
* on the cpu, NULL otherwise
|
|
*/
|
|
static struct task_struct *pick_highest_pushable_task(struct rq *rq, int cpu)
|
|
{
|
|
struct plist_head *head = &rq->rt.pushable_tasks;
|
|
struct task_struct *p;
|
|
|
|
if (!has_pushable_tasks(rq))
|
|
return NULL;
|
|
|
|
plist_for_each_entry(p, head, pushable_tasks) {
|
|
if (pick_rt_task(rq, p, cpu))
|
|
return p;
|
|
}
|
|
|
|
return NULL;
|
|
}
|
|
|
|
static DEFINE_PER_CPU(cpumask_var_t, local_cpu_mask);
|
|
|
|
static int find_lowest_rq(struct task_struct *task)
|
|
{
|
|
struct sched_domain *sd;
|
|
struct cpumask *lowest_mask = this_cpu_cpumask_var_ptr(local_cpu_mask);
|
|
int this_cpu = smp_processor_id();
|
|
int cpu = task_cpu(task);
|
|
|
|
/* Make sure the mask is initialized first */
|
|
if (unlikely(!lowest_mask))
|
|
return -1;
|
|
|
|
if (task->nr_cpus_allowed == 1)
|
|
return -1; /* No other targets possible */
|
|
|
|
if (!cpupri_find(&task_rq(task)->rd->cpupri, task, lowest_mask))
|
|
return -1; /* No targets found */
|
|
|
|
/*
|
|
* At this point we have built a mask of cpus representing the
|
|
* lowest priority tasks in the system. Now we want to elect
|
|
* the best one based on our affinity and topology.
|
|
*
|
|
* We prioritize the last cpu that the task executed on since
|
|
* it is most likely cache-hot in that location.
|
|
*/
|
|
if (cpumask_test_cpu(cpu, lowest_mask))
|
|
return cpu;
|
|
|
|
/*
|
|
* Otherwise, we consult the sched_domains span maps to figure
|
|
* out which cpu is logically closest to our hot cache data.
|
|
*/
|
|
if (!cpumask_test_cpu(this_cpu, lowest_mask))
|
|
this_cpu = -1; /* Skip this_cpu opt if not among lowest */
|
|
|
|
rcu_read_lock();
|
|
for_each_domain(cpu, sd) {
|
|
if (sd->flags & SD_WAKE_AFFINE) {
|
|
int best_cpu;
|
|
|
|
/*
|
|
* "this_cpu" is cheaper to preempt than a
|
|
* remote processor.
|
|
*/
|
|
if (this_cpu != -1 &&
|
|
cpumask_test_cpu(this_cpu, sched_domain_span(sd))) {
|
|
rcu_read_unlock();
|
|
return this_cpu;
|
|
}
|
|
|
|
best_cpu = cpumask_first_and(lowest_mask,
|
|
sched_domain_span(sd));
|
|
if (best_cpu < nr_cpu_ids) {
|
|
rcu_read_unlock();
|
|
return best_cpu;
|
|
}
|
|
}
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
/*
|
|
* And finally, if there were no matches within the domains
|
|
* just give the caller *something* to work with from the compatible
|
|
* locations.
|
|
*/
|
|
if (this_cpu != -1)
|
|
return this_cpu;
|
|
|
|
cpu = cpumask_any(lowest_mask);
|
|
if (cpu < nr_cpu_ids)
|
|
return cpu;
|
|
return -1;
|
|
}
|
|
|
|
/* Will lock the rq it finds */
|
|
static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
|
|
{
|
|
struct rq *lowest_rq = NULL;
|
|
int tries;
|
|
int cpu;
|
|
|
|
for (tries = 0; tries < RT_MAX_TRIES; tries++) {
|
|
cpu = find_lowest_rq(task);
|
|
|
|
if ((cpu == -1) || (cpu == rq->cpu))
|
|
break;
|
|
|
|
lowest_rq = cpu_rq(cpu);
|
|
|
|
if (lowest_rq->rt.highest_prio.curr <= task->prio) {
|
|
/*
|
|
* Target rq has tasks of equal or higher priority,
|
|
* retrying does not release any lock and is unlikely
|
|
* to yield a different result.
|
|
*/
|
|
lowest_rq = NULL;
|
|
break;
|
|
}
|
|
|
|
/* if the prio of this runqueue changed, try again */
|
|
if (double_lock_balance(rq, lowest_rq)) {
|
|
/*
|
|
* We had to unlock the run queue. In
|
|
* the mean time, task could have
|
|
* migrated already or had its affinity changed.
|
|
* Also make sure that it wasn't scheduled on its rq.
|
|
*/
|
|
if (unlikely(task_rq(task) != rq ||
|
|
!cpumask_test_cpu(lowest_rq->cpu, &task->cpus_allowed) ||
|
|
task_running(rq, task) ||
|
|
!rt_task(task) ||
|
|
!task_on_rq_queued(task))) {
|
|
|
|
double_unlock_balance(rq, lowest_rq);
|
|
lowest_rq = NULL;
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* If this rq is still suitable use it. */
|
|
if (lowest_rq->rt.highest_prio.curr > task->prio)
|
|
break;
|
|
|
|
/* try again */
|
|
double_unlock_balance(rq, lowest_rq);
|
|
lowest_rq = NULL;
|
|
}
|
|
|
|
return lowest_rq;
|
|
}
|
|
|
|
static struct task_struct *pick_next_pushable_task(struct rq *rq)
|
|
{
|
|
struct task_struct *p;
|
|
|
|
if (!has_pushable_tasks(rq))
|
|
return NULL;
|
|
|
|
p = plist_first_entry(&rq->rt.pushable_tasks,
|
|
struct task_struct, pushable_tasks);
|
|
|
|
BUG_ON(rq->cpu != task_cpu(p));
|
|
BUG_ON(task_current(rq, p));
|
|
BUG_ON(p->nr_cpus_allowed <= 1);
|
|
|
|
BUG_ON(!task_on_rq_queued(p));
|
|
BUG_ON(!rt_task(p));
|
|
|
|
return p;
|
|
}
|
|
|
|
/*
|
|
* If the current CPU has more than one RT task, see if the non
|
|
* running task can migrate over to a CPU that is running a task
|
|
* of lesser priority.
|
|
*/
|
|
static int push_rt_task(struct rq *rq)
|
|
{
|
|
struct task_struct *next_task;
|
|
struct rq *lowest_rq;
|
|
int ret = 0;
|
|
|
|
if (!rq->rt.overloaded)
|
|
return 0;
|
|
|
|
next_task = pick_next_pushable_task(rq);
|
|
if (!next_task)
|
|
return 0;
|
|
|
|
retry:
|
|
if (unlikely(next_task == rq->curr)) {
|
|
WARN_ON(1);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* It's possible that the next_task slipped in of
|
|
* higher priority than current. If that's the case
|
|
* just reschedule current.
|
|
*/
|
|
if (unlikely(next_task->prio < rq->curr->prio)) {
|
|
resched_curr(rq);
|
|
return 0;
|
|
}
|
|
|
|
/* We might release rq lock */
|
|
get_task_struct(next_task);
|
|
|
|
/* find_lock_lowest_rq locks the rq if found */
|
|
lowest_rq = find_lock_lowest_rq(next_task, rq);
|
|
if (!lowest_rq) {
|
|
struct task_struct *task;
|
|
/*
|
|
* find_lock_lowest_rq releases rq->lock
|
|
* so it is possible that next_task has migrated.
|
|
*
|
|
* We need to make sure that the task is still on the same
|
|
* run-queue and is also still the next task eligible for
|
|
* pushing.
|
|
*/
|
|
task = pick_next_pushable_task(rq);
|
|
if (task == next_task) {
|
|
/*
|
|
* The task hasn't migrated, and is still the next
|
|
* eligible task, but we failed to find a run-queue
|
|
* to push it to. Do not retry in this case, since
|
|
* other cpus will pull from us when ready.
|
|
*/
|
|
goto out;
|
|
}
|
|
|
|
if (!task)
|
|
/* No more tasks, just exit */
|
|
goto out;
|
|
|
|
/*
|
|
* Something has shifted, try again.
|
|
*/
|
|
put_task_struct(next_task);
|
|
next_task = task;
|
|
goto retry;
|
|
}
|
|
|
|
deactivate_task(rq, next_task, 0);
|
|
set_task_cpu(next_task, lowest_rq->cpu);
|
|
activate_task(lowest_rq, next_task, 0);
|
|
ret = 1;
|
|
|
|
resched_curr(lowest_rq);
|
|
|
|
double_unlock_balance(rq, lowest_rq);
|
|
|
|
out:
|
|
put_task_struct(next_task);
|
|
|
|
return ret;
|
|
}
|
|
|
|
static void push_rt_tasks(struct rq *rq)
|
|
{
|
|
/* push_rt_task will return true if it moved an RT */
|
|
while (push_rt_task(rq))
|
|
;
|
|
}
|
|
|
|
#ifdef HAVE_RT_PUSH_IPI
|
|
|
|
/*
|
|
* When a high priority task schedules out from a CPU and a lower priority
|
|
* task is scheduled in, a check is made to see if there's any RT tasks
|
|
* on other CPUs that are waiting to run because a higher priority RT task
|
|
* is currently running on its CPU. In this case, the CPU with multiple RT
|
|
* tasks queued on it (overloaded) needs to be notified that a CPU has opened
|
|
* up that may be able to run one of its non-running queued RT tasks.
|
|
*
|
|
* All CPUs with overloaded RT tasks need to be notified as there is currently
|
|
* no way to know which of these CPUs have the highest priority task waiting
|
|
* to run. Instead of trying to take a spinlock on each of these CPUs,
|
|
* which has shown to cause large latency when done on machines with many
|
|
* CPUs, sending an IPI to the CPUs to have them push off the overloaded
|
|
* RT tasks waiting to run.
|
|
*
|
|
* Just sending an IPI to each of the CPUs is also an issue, as on large
|
|
* count CPU machines, this can cause an IPI storm on a CPU, especially
|
|
* if its the only CPU with multiple RT tasks queued, and a large number
|
|
* of CPUs scheduling a lower priority task at the same time.
|
|
*
|
|
* Each root domain has its own irq work function that can iterate over
|
|
* all CPUs with RT overloaded tasks. Since all CPUs with overloaded RT
|
|
* tassk must be checked if there's one or many CPUs that are lowering
|
|
* their priority, there's a single irq work iterator that will try to
|
|
* push off RT tasks that are waiting to run.
|
|
*
|
|
* When a CPU schedules a lower priority task, it will kick off the
|
|
* irq work iterator that will jump to each CPU with overloaded RT tasks.
|
|
* As it only takes the first CPU that schedules a lower priority task
|
|
* to start the process, the rto_start variable is incremented and if
|
|
* the atomic result is one, then that CPU will try to take the rto_lock.
|
|
* This prevents high contention on the lock as the process handles all
|
|
* CPUs scheduling lower priority tasks.
|
|
*
|
|
* All CPUs that are scheduling a lower priority task will increment the
|
|
* rt_loop_next variable. This will make sure that the irq work iterator
|
|
* checks all RT overloaded CPUs whenever a CPU schedules a new lower
|
|
* priority task, even if the iterator is in the middle of a scan. Incrementing
|
|
* the rt_loop_next will cause the iterator to perform another scan.
|
|
*
|
|
*/
|
|
static int rto_next_cpu(struct root_domain *rd)
|
|
{
|
|
int next;
|
|
int cpu;
|
|
|
|
/*
|
|
* When starting the IPI RT pushing, the rto_cpu is set to -1,
|
|
* rt_next_cpu() will simply return the first CPU found in
|
|
* the rto_mask.
|
|
*
|
|
* If rto_next_cpu() is called with rto_cpu is a valid cpu, it
|
|
* will return the next CPU found in the rto_mask.
|
|
*
|
|
* If there are no more CPUs left in the rto_mask, then a check is made
|
|
* against rto_loop and rto_loop_next. rto_loop is only updated with
|
|
* the rto_lock held, but any CPU may increment the rto_loop_next
|
|
* without any locking.
|
|
*/
|
|
for (;;) {
|
|
|
|
/* When rto_cpu is -1 this acts like cpumask_first() */
|
|
cpu = cpumask_next(rd->rto_cpu, rd->rto_mask);
|
|
|
|
rd->rto_cpu = cpu;
|
|
|
|
if (cpu < nr_cpu_ids)
|
|
return cpu;
|
|
|
|
rd->rto_cpu = -1;
|
|
|
|
/*
|
|
* ACQUIRE ensures we see the @rto_mask changes
|
|
* made prior to the @next value observed.
|
|
*
|
|
* Matches WMB in rt_set_overload().
|
|
*/
|
|
next = atomic_read_acquire(&rd->rto_loop_next);
|
|
|
|
if (rd->rto_loop == next)
|
|
break;
|
|
|
|
rd->rto_loop = next;
|
|
}
|
|
|
|
return -1;
|
|
}
|
|
|
|
static inline bool rto_start_trylock(atomic_t *v)
|
|
{
|
|
return !atomic_cmpxchg_acquire(v, 0, 1);
|
|
}
|
|
|
|
static inline void rto_start_unlock(atomic_t *v)
|
|
{
|
|
atomic_set_release(v, 0);
|
|
}
|
|
|
|
static void tell_cpu_to_push(struct rq *rq)
|
|
{
|
|
int cpu = -1;
|
|
|
|
/* Keep the loop going if the IPI is currently active */
|
|
atomic_inc(&rq->rd->rto_loop_next);
|
|
|
|
/* Only one CPU can initiate a loop at a time */
|
|
if (!rto_start_trylock(&rq->rd->rto_loop_start))
|
|
return;
|
|
|
|
raw_spin_lock(&rq->rd->rto_lock);
|
|
|
|
/*
|
|
* The rto_cpu is updated under the lock, if it has a valid cpu
|
|
* then the IPI is still running and will continue due to the
|
|
* update to loop_next, and nothing needs to be done here.
|
|
* Otherwise it is finishing up and an ipi needs to be sent.
|
|
*/
|
|
if (rq->rd->rto_cpu < 0)
|
|
cpu = rto_next_cpu(rq->rd);
|
|
|
|
raw_spin_unlock(&rq->rd->rto_lock);
|
|
|
|
rto_start_unlock(&rq->rd->rto_loop_start);
|
|
|
|
if (cpu >= 0) {
|
|
/* Make sure the rd does not get freed while pushing */
|
|
sched_get_rd(rq->rd);
|
|
irq_work_queue_on(&rq->rd->rto_push_work, cpu);
|
|
}
|
|
}
|
|
|
|
/* Called from hardirq context */
|
|
void rto_push_irq_work_func(struct irq_work *work)
|
|
{
|
|
struct root_domain *rd =
|
|
container_of(work, struct root_domain, rto_push_work);
|
|
struct rq *rq;
|
|
int cpu;
|
|
|
|
rq = this_rq();
|
|
|
|
/*
|
|
* We do not need to grab the lock to check for has_pushable_tasks.
|
|
* When it gets updated, a check is made if a push is possible.
|
|
*/
|
|
if (has_pushable_tasks(rq)) {
|
|
raw_spin_lock(&rq->lock);
|
|
push_rt_tasks(rq);
|
|
raw_spin_unlock(&rq->lock);
|
|
}
|
|
|
|
raw_spin_lock(&rd->rto_lock);
|
|
|
|
/* Pass the IPI to the next rt overloaded queue */
|
|
cpu = rto_next_cpu(rd);
|
|
|
|
raw_spin_unlock(&rd->rto_lock);
|
|
|
|
if (cpu < 0) {
|
|
sched_put_rd(rd);
|
|
return;
|
|
}
|
|
|
|
/* Try the next RT overloaded CPU */
|
|
irq_work_queue_on(&rd->rto_push_work, cpu);
|
|
}
|
|
#endif /* HAVE_RT_PUSH_IPI */
|
|
|
|
static void pull_rt_task(struct rq *this_rq)
|
|
{
|
|
int this_cpu = this_rq->cpu, cpu;
|
|
bool resched = false;
|
|
struct task_struct *p;
|
|
struct rq *src_rq;
|
|
int rt_overload_count = rt_overloaded(this_rq);
|
|
|
|
if (likely(!rt_overload_count))
|
|
return;
|
|
|
|
/*
|
|
* Match the barrier from rt_set_overloaded; this guarantees that if we
|
|
* see overloaded we must also see the rto_mask bit.
|
|
*/
|
|
smp_rmb();
|
|
|
|
/* If we are the only overloaded CPU do nothing */
|
|
if (rt_overload_count == 1 &&
|
|
cpumask_test_cpu(this_rq->cpu, this_rq->rd->rto_mask))
|
|
return;
|
|
|
|
#ifdef HAVE_RT_PUSH_IPI
|
|
if (sched_feat(RT_PUSH_IPI)) {
|
|
tell_cpu_to_push(this_rq);
|
|
return;
|
|
}
|
|
#endif
|
|
|
|
for_each_cpu(cpu, this_rq->rd->rto_mask) {
|
|
if (this_cpu == cpu)
|
|
continue;
|
|
|
|
src_rq = cpu_rq(cpu);
|
|
|
|
/*
|
|
* Don't bother taking the src_rq->lock if the next highest
|
|
* task is known to be lower-priority than our current task.
|
|
* This may look racy, but if this value is about to go
|
|
* logically higher, the src_rq will push this task away.
|
|
* And if its going logically lower, we do not care
|
|
*/
|
|
if (src_rq->rt.highest_prio.next >=
|
|
this_rq->rt.highest_prio.curr)
|
|
continue;
|
|
|
|
/*
|
|
* We can potentially drop this_rq's lock in
|
|
* double_lock_balance, and another CPU could
|
|
* alter this_rq
|
|
*/
|
|
double_lock_balance(this_rq, src_rq);
|
|
|
|
/*
|
|
* We can pull only a task, which is pushable
|
|
* on its rq, and no others.
|
|
*/
|
|
p = pick_highest_pushable_task(src_rq, this_cpu);
|
|
|
|
/*
|
|
* Do we have an RT task that preempts
|
|
* the to-be-scheduled task?
|
|
*/
|
|
if (p && (p->prio < this_rq->rt.highest_prio.curr)) {
|
|
WARN_ON(p == src_rq->curr);
|
|
WARN_ON(!task_on_rq_queued(p));
|
|
|
|
/*
|
|
* There's a chance that p is higher in priority
|
|
* than what's currently running on its cpu.
|
|
* This is just that p is wakeing up and hasn't
|
|
* had a chance to schedule. We only pull
|
|
* p if it is lower in priority than the
|
|
* current task on the run queue
|
|
*/
|
|
if (p->prio < src_rq->curr->prio)
|
|
goto skip;
|
|
|
|
resched = true;
|
|
|
|
deactivate_task(src_rq, p, 0);
|
|
set_task_cpu(p, this_cpu);
|
|
activate_task(this_rq, p, 0);
|
|
/*
|
|
* We continue with the search, just in
|
|
* case there's an even higher prio task
|
|
* in another runqueue. (low likelihood
|
|
* but possible)
|
|
*/
|
|
}
|
|
skip:
|
|
double_unlock_balance(this_rq, src_rq);
|
|
}
|
|
|
|
if (resched)
|
|
resched_curr(this_rq);
|
|
}
|
|
|
|
/*
|
|
* If we are not running and we are not going to reschedule soon, we should
|
|
* try to push tasks away now
|
|
*/
|
|
static void task_woken_rt(struct rq *rq, struct task_struct *p)
|
|
{
|
|
if (!task_running(rq, p) &&
|
|
!test_tsk_need_resched(rq->curr) &&
|
|
p->nr_cpus_allowed > 1 &&
|
|
(dl_task(rq->curr) || rt_task(rq->curr)) &&
|
|
(rq->curr->nr_cpus_allowed < 2 ||
|
|
rq->curr->prio <= p->prio))
|
|
push_rt_tasks(rq);
|
|
}
|
|
|
|
/* Assumes rq->lock is held */
|
|
static void rq_online_rt(struct rq *rq)
|
|
{
|
|
if (rq->rt.overloaded)
|
|
rt_set_overload(rq);
|
|
|
|
__enable_runtime(rq);
|
|
|
|
cpupri_set(&rq->rd->cpupri, rq->cpu, rq->rt.highest_prio.curr);
|
|
}
|
|
|
|
/* Assumes rq->lock is held */
|
|
static void rq_offline_rt(struct rq *rq)
|
|
{
|
|
if (rq->rt.overloaded)
|
|
rt_clear_overload(rq);
|
|
|
|
__disable_runtime(rq);
|
|
|
|
cpupri_set(&rq->rd->cpupri, rq->cpu, CPUPRI_INVALID);
|
|
}
|
|
|
|
/*
|
|
* When switch from the rt queue, we bring ourselves to a position
|
|
* that we might want to pull RT tasks from other runqueues.
|
|
*/
|
|
static void switched_from_rt(struct rq *rq, struct task_struct *p)
|
|
{
|
|
/*
|
|
* If there are other RT tasks then we will reschedule
|
|
* and the scheduling of the other RT tasks will handle
|
|
* the balancing. But if we are the last RT task
|
|
* we may need to handle the pulling of RT tasks
|
|
* now.
|
|
*/
|
|
if (!task_on_rq_queued(p) || rq->rt.rt_nr_running)
|
|
return;
|
|
|
|
queue_pull_task(rq);
|
|
}
|
|
|
|
void __init init_sched_rt_class(void)
|
|
{
|
|
unsigned int i;
|
|
|
|
for_each_possible_cpu(i) {
|
|
zalloc_cpumask_var_node(&per_cpu(local_cpu_mask, i),
|
|
GFP_KERNEL, cpu_to_node(i));
|
|
}
|
|
}
|
|
#endif /* CONFIG_SMP */
|
|
|
|
/*
|
|
* When switching a task to RT, we may overload the runqueue
|
|
* with RT tasks. In this case we try to push them off to
|
|
* other runqueues.
|
|
*/
|
|
static void switched_to_rt(struct rq *rq, struct task_struct *p)
|
|
{
|
|
/*
|
|
* If we are already running, then there's nothing
|
|
* that needs to be done. But if we are not running
|
|
* we may need to preempt the current running task.
|
|
* If that current running task is also an RT task
|
|
* then see if we can move to another run queue.
|
|
*/
|
|
if (task_on_rq_queued(p) && rq->curr != p) {
|
|
#ifdef CONFIG_SMP
|
|
if (p->nr_cpus_allowed > 1 && rq->rt.overloaded)
|
|
queue_push_tasks(rq);
|
|
#endif /* CONFIG_SMP */
|
|
if (p->prio < rq->curr->prio && cpu_online(cpu_of(rq)))
|
|
resched_curr(rq);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Priority of the task has changed. This may cause
|
|
* us to initiate a push or pull.
|
|
*/
|
|
static void
|
|
prio_changed_rt(struct rq *rq, struct task_struct *p, int oldprio)
|
|
{
|
|
if (!task_on_rq_queued(p))
|
|
return;
|
|
|
|
if (rq->curr == p) {
|
|
#ifdef CONFIG_SMP
|
|
/*
|
|
* If our priority decreases while running, we
|
|
* may need to pull tasks to this runqueue.
|
|
*/
|
|
if (oldprio < p->prio)
|
|
queue_pull_task(rq);
|
|
|
|
/*
|
|
* If there's a higher priority task waiting to run
|
|
* then reschedule.
|
|
*/
|
|
if (p->prio > rq->rt.highest_prio.curr)
|
|
resched_curr(rq);
|
|
#else
|
|
/* For UP simply resched on drop of prio */
|
|
if (oldprio < p->prio)
|
|
resched_curr(rq);
|
|
#endif /* CONFIG_SMP */
|
|
} else {
|
|
/*
|
|
* This task is not running, but if it is
|
|
* greater than the current running task
|
|
* then reschedule.
|
|
*/
|
|
if (p->prio < rq->curr->prio)
|
|
resched_curr(rq);
|
|
}
|
|
}
|
|
|
|
#ifdef CONFIG_POSIX_TIMERS
|
|
static void watchdog(struct rq *rq, struct task_struct *p)
|
|
{
|
|
unsigned long soft, hard;
|
|
|
|
/* max may change after cur was read, this will be fixed next tick */
|
|
soft = task_rlimit(p, RLIMIT_RTTIME);
|
|
hard = task_rlimit_max(p, RLIMIT_RTTIME);
|
|
|
|
if (soft != RLIM_INFINITY) {
|
|
unsigned long next;
|
|
|
|
if (p->rt.watchdog_stamp != jiffies) {
|
|
p->rt.timeout++;
|
|
p->rt.watchdog_stamp = jiffies;
|
|
}
|
|
|
|
next = DIV_ROUND_UP(min(soft, hard), USEC_PER_SEC/HZ);
|
|
if (p->rt.timeout > next)
|
|
p->cputime_expires.sched_exp = p->se.sum_exec_runtime;
|
|
}
|
|
}
|
|
#else
|
|
static inline void watchdog(struct rq *rq, struct task_struct *p) { }
|
|
#endif
|
|
|
|
static void task_tick_rt(struct rq *rq, struct task_struct *p, int queued)
|
|
{
|
|
struct sched_rt_entity *rt_se = &p->rt;
|
|
|
|
update_curr_rt(rq);
|
|
|
|
watchdog(rq, p);
|
|
|
|
/*
|
|
* RR tasks need a special form of timeslice management.
|
|
* FIFO tasks have no timeslices.
|
|
*/
|
|
if (p->policy != SCHED_RR)
|
|
return;
|
|
|
|
if (--p->rt.time_slice)
|
|
return;
|
|
|
|
p->rt.time_slice = sched_rr_timeslice;
|
|
|
|
/*
|
|
* Requeue to the end of queue if we (and all of our ancestors) are not
|
|
* the only element on the queue
|
|
*/
|
|
for_each_sched_rt_entity(rt_se) {
|
|
if (rt_se->run_list.prev != rt_se->run_list.next) {
|
|
requeue_task_rt(rq, p, 0);
|
|
resched_curr(rq);
|
|
return;
|
|
}
|
|
}
|
|
}
|
|
|
|
static void set_curr_task_rt(struct rq *rq)
|
|
{
|
|
struct task_struct *p = rq->curr;
|
|
|
|
p->se.exec_start = rq_clock_task(rq);
|
|
|
|
/* The running task is never eligible for pushing */
|
|
dequeue_pushable_task(rq, p);
|
|
}
|
|
|
|
static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
|
|
{
|
|
/*
|
|
* Time slice is 0 for SCHED_FIFO tasks
|
|
*/
|
|
if (task->policy == SCHED_RR)
|
|
return sched_rr_timeslice;
|
|
else
|
|
return 0;
|
|
}
|
|
|
|
const struct sched_class rt_sched_class = {
|
|
.next = &fair_sched_class,
|
|
.enqueue_task = enqueue_task_rt,
|
|
.dequeue_task = dequeue_task_rt,
|
|
.yield_task = yield_task_rt,
|
|
|
|
.check_preempt_curr = check_preempt_curr_rt,
|
|
|
|
.pick_next_task = pick_next_task_rt,
|
|
.put_prev_task = put_prev_task_rt,
|
|
|
|
#ifdef CONFIG_SMP
|
|
.select_task_rq = select_task_rq_rt,
|
|
|
|
.set_cpus_allowed = set_cpus_allowed_common,
|
|
.rq_online = rq_online_rt,
|
|
.rq_offline = rq_offline_rt,
|
|
.task_woken = task_woken_rt,
|
|
.switched_from = switched_from_rt,
|
|
#endif
|
|
|
|
.set_curr_task = set_curr_task_rt,
|
|
.task_tick = task_tick_rt,
|
|
|
|
.get_rr_interval = get_rr_interval_rt,
|
|
|
|
.prio_changed = prio_changed_rt,
|
|
.switched_to = switched_to_rt,
|
|
|
|
.update_curr = update_curr_rt,
|
|
};
|
|
|
|
#ifdef CONFIG_RT_GROUP_SCHED
|
|
/*
|
|
* Ensure that the real time constraints are schedulable.
|
|
*/
|
|
static DEFINE_MUTEX(rt_constraints_mutex);
|
|
|
|
/* Must be called with tasklist_lock held */
|
|
static inline int tg_has_rt_tasks(struct task_group *tg)
|
|
{
|
|
struct task_struct *g, *p;
|
|
|
|
/*
|
|
* Autogroups do not have RT tasks; see autogroup_create().
|
|
*/
|
|
if (task_group_is_autogroup(tg))
|
|
return 0;
|
|
|
|
for_each_process_thread(g, p) {
|
|
if (rt_task(p) && task_group(p) == tg)
|
|
return 1;
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
struct rt_schedulable_data {
|
|
struct task_group *tg;
|
|
u64 rt_period;
|
|
u64 rt_runtime;
|
|
};
|
|
|
|
static int tg_rt_schedulable(struct task_group *tg, void *data)
|
|
{
|
|
struct rt_schedulable_data *d = data;
|
|
struct task_group *child;
|
|
unsigned long total, sum = 0;
|
|
u64 period, runtime;
|
|
|
|
period = ktime_to_ns(tg->rt_bandwidth.rt_period);
|
|
runtime = tg->rt_bandwidth.rt_runtime;
|
|
|
|
if (tg == d->tg) {
|
|
period = d->rt_period;
|
|
runtime = d->rt_runtime;
|
|
}
|
|
|
|
/*
|
|
* Cannot have more runtime than the period.
|
|
*/
|
|
if (runtime > period && runtime != RUNTIME_INF)
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* Ensure we don't starve existing RT tasks.
|
|
*/
|
|
if (rt_bandwidth_enabled() && !runtime && tg_has_rt_tasks(tg))
|
|
return -EBUSY;
|
|
|
|
total = to_ratio(period, runtime);
|
|
|
|
/*
|
|
* Nobody can have more than the global setting allows.
|
|
*/
|
|
if (total > to_ratio(global_rt_period(), global_rt_runtime()))
|
|
return -EINVAL;
|
|
|
|
/*
|
|
* The sum of our children's runtime should not exceed our own.
|
|
*/
|
|
list_for_each_entry_rcu(child, &tg->children, siblings) {
|
|
period = ktime_to_ns(child->rt_bandwidth.rt_period);
|
|
runtime = child->rt_bandwidth.rt_runtime;
|
|
|
|
if (child == d->tg) {
|
|
period = d->rt_period;
|
|
runtime = d->rt_runtime;
|
|
}
|
|
|
|
sum += to_ratio(period, runtime);
|
|
}
|
|
|
|
if (sum > total)
|
|
return -EINVAL;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int __rt_schedulable(struct task_group *tg, u64 period, u64 runtime)
|
|
{
|
|
int ret;
|
|
|
|
struct rt_schedulable_data data = {
|
|
.tg = tg,
|
|
.rt_period = period,
|
|
.rt_runtime = runtime,
|
|
};
|
|
|
|
rcu_read_lock();
|
|
ret = walk_tg_tree(tg_rt_schedulable, tg_nop, &data);
|
|
rcu_read_unlock();
|
|
|
|
return ret;
|
|
}
|
|
|
|
static int tg_set_rt_bandwidth(struct task_group *tg,
|
|
u64 rt_period, u64 rt_runtime)
|
|
{
|
|
int i, err = 0;
|
|
|
|
/*
|
|
* Disallowing the root group RT runtime is BAD, it would disallow the
|
|
* kernel creating (and or operating) RT threads.
|
|
*/
|
|
if (tg == &root_task_group && rt_runtime == 0)
|
|
return -EINVAL;
|
|
|
|
/* No period doesn't make any sense. */
|
|
if (rt_period == 0)
|
|
return -EINVAL;
|
|
|
|
mutex_lock(&rt_constraints_mutex);
|
|
read_lock(&tasklist_lock);
|
|
err = __rt_schedulable(tg, rt_period, rt_runtime);
|
|
if (err)
|
|
goto unlock;
|
|
|
|
raw_spin_lock_irq(&tg->rt_bandwidth.rt_runtime_lock);
|
|
tg->rt_bandwidth.rt_period = ns_to_ktime(rt_period);
|
|
tg->rt_bandwidth.rt_runtime = rt_runtime;
|
|
|
|
for_each_possible_cpu(i) {
|
|
struct rt_rq *rt_rq = tg->rt_rq[i];
|
|
|
|
raw_spin_lock(&rt_rq->rt_runtime_lock);
|
|
rt_rq->rt_runtime = rt_runtime;
|
|
raw_spin_unlock(&rt_rq->rt_runtime_lock);
|
|
}
|
|
raw_spin_unlock_irq(&tg->rt_bandwidth.rt_runtime_lock);
|
|
unlock:
|
|
read_unlock(&tasklist_lock);
|
|
mutex_unlock(&rt_constraints_mutex);
|
|
|
|
return err;
|
|
}
|
|
|
|
int sched_group_set_rt_runtime(struct task_group *tg, long rt_runtime_us)
|
|
{
|
|
u64 rt_runtime, rt_period;
|
|
|
|
rt_period = ktime_to_ns(tg->rt_bandwidth.rt_period);
|
|
rt_runtime = (u64)rt_runtime_us * NSEC_PER_USEC;
|
|
if (rt_runtime_us < 0)
|
|
rt_runtime = RUNTIME_INF;
|
|
|
|
return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
|
|
}
|
|
|
|
long sched_group_rt_runtime(struct task_group *tg)
|
|
{
|
|
u64 rt_runtime_us;
|
|
|
|
if (tg->rt_bandwidth.rt_runtime == RUNTIME_INF)
|
|
return -1;
|
|
|
|
rt_runtime_us = tg->rt_bandwidth.rt_runtime;
|
|
do_div(rt_runtime_us, NSEC_PER_USEC);
|
|
return rt_runtime_us;
|
|
}
|
|
|
|
int sched_group_set_rt_period(struct task_group *tg, u64 rt_period_us)
|
|
{
|
|
u64 rt_runtime, rt_period;
|
|
|
|
rt_period = rt_period_us * NSEC_PER_USEC;
|
|
rt_runtime = tg->rt_bandwidth.rt_runtime;
|
|
|
|
return tg_set_rt_bandwidth(tg, rt_period, rt_runtime);
|
|
}
|
|
|
|
long sched_group_rt_period(struct task_group *tg)
|
|
{
|
|
u64 rt_period_us;
|
|
|
|
rt_period_us = ktime_to_ns(tg->rt_bandwidth.rt_period);
|
|
do_div(rt_period_us, NSEC_PER_USEC);
|
|
return rt_period_us;
|
|
}
|
|
|
|
static int sched_rt_global_constraints(void)
|
|
{
|
|
int ret = 0;
|
|
|
|
mutex_lock(&rt_constraints_mutex);
|
|
read_lock(&tasklist_lock);
|
|
ret = __rt_schedulable(NULL, 0, 0);
|
|
read_unlock(&tasklist_lock);
|
|
mutex_unlock(&rt_constraints_mutex);
|
|
|
|
return ret;
|
|
}
|
|
|
|
int sched_rt_can_attach(struct task_group *tg, struct task_struct *tsk)
|
|
{
|
|
/* Don't accept realtime tasks when there is no way for them to run */
|
|
if (rt_task(tsk) && tg->rt_bandwidth.rt_runtime == 0)
|
|
return 0;
|
|
|
|
return 1;
|
|
}
|
|
|
|
#else /* !CONFIG_RT_GROUP_SCHED */
|
|
static int sched_rt_global_constraints(void)
|
|
{
|
|
unsigned long flags;
|
|
int i;
|
|
|
|
raw_spin_lock_irqsave(&def_rt_bandwidth.rt_runtime_lock, flags);
|
|
for_each_possible_cpu(i) {
|
|
struct rt_rq *rt_rq = &cpu_rq(i)->rt;
|
|
|
|
raw_spin_lock(&rt_rq->rt_runtime_lock);
|
|
rt_rq->rt_runtime = global_rt_runtime();
|
|
raw_spin_unlock(&rt_rq->rt_runtime_lock);
|
|
}
|
|
raw_spin_unlock_irqrestore(&def_rt_bandwidth.rt_runtime_lock, flags);
|
|
|
|
return 0;
|
|
}
|
|
#endif /* CONFIG_RT_GROUP_SCHED */
|
|
|
|
static int sched_rt_global_validate(void)
|
|
{
|
|
if (sysctl_sched_rt_period <= 0)
|
|
return -EINVAL;
|
|
|
|
if ((sysctl_sched_rt_runtime != RUNTIME_INF) &&
|
|
(sysctl_sched_rt_runtime > sysctl_sched_rt_period))
|
|
return -EINVAL;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void sched_rt_do_global(void)
|
|
{
|
|
def_rt_bandwidth.rt_runtime = global_rt_runtime();
|
|
def_rt_bandwidth.rt_period = ns_to_ktime(global_rt_period());
|
|
}
|
|
|
|
int sched_rt_handler(struct ctl_table *table, int write,
|
|
void __user *buffer, size_t *lenp,
|
|
loff_t *ppos)
|
|
{
|
|
int old_period, old_runtime;
|
|
static DEFINE_MUTEX(mutex);
|
|
int ret;
|
|
|
|
mutex_lock(&mutex);
|
|
old_period = sysctl_sched_rt_period;
|
|
old_runtime = sysctl_sched_rt_runtime;
|
|
|
|
ret = proc_dointvec(table, write, buffer, lenp, ppos);
|
|
|
|
if (!ret && write) {
|
|
ret = sched_rt_global_validate();
|
|
if (ret)
|
|
goto undo;
|
|
|
|
ret = sched_dl_global_validate();
|
|
if (ret)
|
|
goto undo;
|
|
|
|
ret = sched_rt_global_constraints();
|
|
if (ret)
|
|
goto undo;
|
|
|
|
sched_rt_do_global();
|
|
sched_dl_do_global();
|
|
}
|
|
if (0) {
|
|
undo:
|
|
sysctl_sched_rt_period = old_period;
|
|
sysctl_sched_rt_runtime = old_runtime;
|
|
}
|
|
mutex_unlock(&mutex);
|
|
|
|
return ret;
|
|
}
|
|
|
|
int sched_rr_handler(struct ctl_table *table, int write,
|
|
void __user *buffer, size_t *lenp,
|
|
loff_t *ppos)
|
|
{
|
|
int ret;
|
|
static DEFINE_MUTEX(mutex);
|
|
|
|
mutex_lock(&mutex);
|
|
ret = proc_dointvec(table, write, buffer, lenp, ppos);
|
|
/*
|
|
* Make sure that internally we keep jiffies.
|
|
* Also, writing zero resets the timeslice to default:
|
|
*/
|
|
if (!ret && write) {
|
|
sched_rr_timeslice =
|
|
sysctl_sched_rr_timeslice <= 0 ? RR_TIMESLICE :
|
|
msecs_to_jiffies(sysctl_sched_rr_timeslice);
|
|
}
|
|
mutex_unlock(&mutex);
|
|
return ret;
|
|
}
|
|
|
|
#ifdef CONFIG_SCHED_DEBUG
|
|
extern void print_rt_rq(struct seq_file *m, int cpu, struct rt_rq *rt_rq);
|
|
|
|
void print_rt_stats(struct seq_file *m, int cpu)
|
|
{
|
|
rt_rq_iter_t iter;
|
|
struct rt_rq *rt_rq;
|
|
|
|
rcu_read_lock();
|
|
for_each_rt_rq(rt_rq, iter, cpu_rq(cpu))
|
|
print_rt_rq(m, cpu, rt_rq);
|
|
rcu_read_unlock();
|
|
}
|
|
#endif /* CONFIG_SCHED_DEBUG */
|