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authorLinus Torvalds <torvalds@linux-foundation.org>2011-06-19 11:56:56 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2011-06-19 11:56:56 -0400
commit357ed6b1a110048ff8106f99092d6c4a7aadb45a (patch)
treeff4eb7e809e547bc3c0680dfd51793a8f57b2063
parentde505e709ffb09a7382ca8e0d8c7dbb171ba5830 (diff)
parentf8b7fc6b514f34a51875dd48dff70d4d17a54f38 (diff)
Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: rcu: Move RCU_BOOST #ifdefs to header file rcu: use softirq instead of kthreads except when RCU_BOOST=y rcu: Use softirq to address performance regression rcu: Simplify curing of load woes
Diffstat
-rw-r--r--Documentation/filesystems/proc.txt1
-rw-r--r--include/linux/interrupt.h1
-rw-r--r--include/trace/events/irq.h3
-rw-r--r--kernel/rcutree.c398
-rw-r--r--kernel/rcutree.h12
-rw-r--r--kernel/rcutree_plugin.h419
-rw-r--r--kernel/rcutree_trace.c32
-rw-r--r--kernel/softirq.c2
-rw-r--r--tools/perf/util/trace-event-parse.c1
9 files changed, 466 insertions, 403 deletions
diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index f48178024067..db3b1aba32a3 100644
--- a/Documentation/filesystems/proc.txt
+++ b/Documentation/filesystems/proc.txt
@@ -843,6 +843,7 @@ Provides counts of softirq handlers serviced since boot time, for each cpu.
843 TASKLET: 0 0 0 290 843 TASKLET: 0 0 0 290
844 SCHED: 27035 26983 26971 26746 844 SCHED: 27035 26983 26971 26746
845 HRTIMER: 0 0 0 0 845 HRTIMER: 0 0 0 0
846 RCU: 1678 1769 2178 2250
846 847
847 848
8481.3 IDE devices in /proc/ide 8491.3 IDE devices in /proc/ide
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 6c12989839d9..f6efed0039ed 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -414,6 +414,7 @@ enum
414 TASKLET_SOFTIRQ, 414 TASKLET_SOFTIRQ,
415 SCHED_SOFTIRQ, 415 SCHED_SOFTIRQ,
416 HRTIMER_SOFTIRQ, 416 HRTIMER_SOFTIRQ,
417 RCU_SOFTIRQ, /* Preferable RCU should always be the last softirq */
417 418
418 NR_SOFTIRQS 419 NR_SOFTIRQS
419}; 420};
diff --git a/include/trace/events/irq.h b/include/trace/events/irq.h
index ae045ca7d356..1c09820df585 100644
--- a/include/trace/events/irq.h
+++ b/include/trace/events/irq.h
@@ -20,7 +20,8 @@ struct softirq_action;
20 softirq_name(BLOCK_IOPOLL), \ 20 softirq_name(BLOCK_IOPOLL), \
21 softirq_name(TASKLET), \ 21 softirq_name(TASKLET), \
22 softirq_name(SCHED), \ 22 softirq_name(SCHED), \
23 softirq_name(HRTIMER)) 23 softirq_name(HRTIMER), \
24 softirq_name(RCU))
24 25
25/** 26/**
26 * irq_handler_entry - called immediately before the irq action handler 27 * irq_handler_entry - called immediately before the irq action handler
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 89419ff92e99..7e59ffb3d0ba 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -87,6 +87,8 @@ static struct rcu_state *rcu_state;
87int rcu_scheduler_active __read_mostly; 87int rcu_scheduler_active __read_mostly;
88EXPORT_SYMBOL_GPL(rcu_scheduler_active); 88EXPORT_SYMBOL_GPL(rcu_scheduler_active);
89 89
90#ifdef CONFIG_RCU_BOOST
91
90/* 92/*
91 * Control variables for per-CPU and per-rcu_node kthreads. These 93 * Control variables for per-CPU and per-rcu_node kthreads. These
92 * handle all flavors of RCU. 94 * handle all flavors of RCU.
@@ -98,8 +100,11 @@ DEFINE_PER_CPU(unsigned int, rcu_cpu_kthread_loops);
98DEFINE_PER_CPU(char, rcu_cpu_has_work); 100DEFINE_PER_CPU(char, rcu_cpu_has_work);
99static char rcu_kthreads_spawnable; 101static char rcu_kthreads_spawnable;
100 102
103#endif /* #ifdef CONFIG_RCU_BOOST */
104
101static void rcu_node_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu); 105static void rcu_node_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu);
102static void invoke_rcu_cpu_kthread(void); 106static void invoke_rcu_core(void);
107static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp);
103 108
104#define RCU_KTHREAD_PRIO 1 /* RT priority for per-CPU kthreads. */ 109#define RCU_KTHREAD_PRIO 1 /* RT priority for per-CPU kthreads. */
105 110
@@ -1088,14 +1093,8 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
1088 int need_report = 0; 1093 int need_report = 0;
1089 struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu); 1094 struct rcu_data *rdp = per_cpu_ptr(rsp->rda, cpu);
1090 struct rcu_node *rnp; 1095 struct rcu_node *rnp;
1091 struct task_struct *t;
1092 1096
1093 /* Stop the CPU's kthread. */ 1097 rcu_stop_cpu_kthread(cpu);
1094 t = per_cpu(rcu_cpu_kthread_task, cpu);
1095 if (t != NULL) {
1096 per_cpu(rcu_cpu_kthread_task, cpu) = NULL;
1097 kthread_stop(t);
1098 }
1099 1098
1100 /* Exclude any attempts to start a new grace period. */ 1099 /* Exclude any attempts to start a new grace period. */
1101 raw_spin_lock_irqsave(&rsp->onofflock, flags); 1100 raw_spin_lock_irqsave(&rsp->onofflock, flags);
@@ -1231,7 +1230,7 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
1231 1230
1232 /* Re-raise the RCU softirq if there are callbacks remaining. */ 1231 /* Re-raise the RCU softirq if there are callbacks remaining. */
1233 if (cpu_has_callbacks_ready_to_invoke(rdp)) 1232 if (cpu_has_callbacks_ready_to_invoke(rdp))
1234 invoke_rcu_cpu_kthread(); 1233 invoke_rcu_core();
1235} 1234}
1236 1235
1237/* 1236/*
@@ -1277,7 +1276,7 @@ void rcu_check_callbacks(int cpu, int user)
1277 } 1276 }
1278 rcu_preempt_check_callbacks(cpu); 1277 rcu_preempt_check_callbacks(cpu);
1279 if (rcu_pending(cpu)) 1278 if (rcu_pending(cpu))
1280 invoke_rcu_cpu_kthread(); 1279 invoke_rcu_core();
1281} 1280}
1282 1281
1283#ifdef CONFIG_SMP 1282#ifdef CONFIG_SMP
@@ -1442,13 +1441,14 @@ __rcu_process_callbacks(struct rcu_state *rsp, struct rcu_data *rdp)
1442 } 1441 }
1443 1442
1444 /* If there are callbacks ready, invoke them. */ 1443 /* If there are callbacks ready, invoke them. */
1445 rcu_do_batch(rsp, rdp); 1444 if (cpu_has_callbacks_ready_to_invoke(rdp))
1445 invoke_rcu_callbacks(rsp, rdp);
1446} 1446}
1447 1447
1448/* 1448/*
1449 * Do softirq processing for the current CPU. 1449 * Do softirq processing for the current CPU.
1450 */ 1450 */
1451static void rcu_process_callbacks(void) 1451static void rcu_process_callbacks(struct softirq_action *unused)
1452{ 1452{
1453 __rcu_process_callbacks(&rcu_sched_state, 1453 __rcu_process_callbacks(&rcu_sched_state,
1454 &__get_cpu_var(rcu_sched_data)); 1454 &__get_cpu_var(rcu_sched_data));
@@ -1465,342 +1465,20 @@ static void rcu_process_callbacks(void)
1465 * the current CPU with interrupts disabled, the rcu_cpu_kthread_task 1465 * the current CPU with interrupts disabled, the rcu_cpu_kthread_task
1466 * cannot disappear out from under us. 1466 * cannot disappear out from under us.
1467 */ 1467 */
1468static void invoke_rcu_cpu_kthread(void) 1468static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp)
1469{
1470 unsigned long flags;
1471
1472 local_irq_save(flags);
1473 __this_cpu_write(rcu_cpu_has_work, 1);
1474 if (__this_cpu_read(rcu_cpu_kthread_task) == NULL) {
1475 local_irq_restore(flags);
1476 return;
1477 }
1478 wake_up_process(__this_cpu_read(rcu_cpu_kthread_task));
1479 local_irq_restore(flags);
1480}
1481
1482/*
1483 * Wake up the specified per-rcu_node-structure kthread.
1484 * Because the per-rcu_node kthreads are immortal, we don't need
1485 * to do anything to keep them alive.
1486 */
1487static void invoke_rcu_node_kthread(struct rcu_node *rnp)
1488{
1489 struct task_struct *t;
1490
1491 t = rnp->node_kthread_task;
1492 if (t != NULL)
1493 wake_up_process(t);
1494}
1495
1496/*
1497 * Set the specified CPU's kthread to run RT or not, as specified by
1498 * the to_rt argument. The CPU-hotplug locks are held, so the task
1499 * is not going away.
1500 */
1501static void rcu_cpu_kthread_setrt(int cpu, int to_rt)
1502{
1503 int policy;
1504 struct sched_param sp;
1505 struct task_struct *t;
1506
1507 t = per_cpu(rcu_cpu_kthread_task, cpu);
1508 if (t == NULL)
1509 return;
1510 if (to_rt) {
1511 policy = SCHED_FIFO;
1512 sp.sched_priority = RCU_KTHREAD_PRIO;
1513 } else {
1514 policy = SCHED_NORMAL;
1515 sp.sched_priority = 0;
1516 }
1517 sched_setscheduler_nocheck(t, policy, &sp);
1518}
1519
1520/*
1521 * Timer handler to initiate the waking up of per-CPU kthreads that
1522 * have yielded the CPU due to excess numbers of RCU callbacks.
1523 * We wake up the per-rcu_node kthread, which in turn will wake up
1524 * the booster kthread.
1525 */
1526static void rcu_cpu_kthread_timer(unsigned long arg)
1527{
1528 struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, arg);
1529 struct rcu_node *rnp = rdp->mynode;
1530
1531 atomic_or(rdp->grpmask, &rnp->wakemask);
1532 invoke_rcu_node_kthread(rnp);
1533}
1534
1535/*
1536 * Drop to non-real-time priority and yield, but only after posting a
1537 * timer that will cause us to regain our real-time priority if we
1538 * remain preempted. Either way, we restore our real-time priority
1539 * before returning.
1540 */
1541static void rcu_yield(void (*f)(unsigned long), unsigned long arg)
1542{
1543 struct sched_param sp;
1544 struct timer_list yield_timer;
1545
1546 setup_timer_on_stack(&yield_timer, f, arg);
1547 mod_timer(&yield_timer, jiffies + 2);
1548 sp.sched_priority = 0;
1549 sched_setscheduler_nocheck(current, SCHED_NORMAL, &sp);
1550 set_user_nice(current, 19);
1551 schedule();
1552 sp.sched_priority = RCU_KTHREAD_PRIO;
1553 sched_setscheduler_nocheck(current, SCHED_FIFO, &sp);
1554 del_timer(&yield_timer);
1555}
1556
1557/*
1558 * Handle cases where the rcu_cpu_kthread() ends up on the wrong CPU.
1559 * This can happen while the corresponding CPU is either coming online
1560 * or going offline. We cannot wait until the CPU is fully online
1561 * before starting the kthread, because the various notifier functions
1562 * can wait for RCU grace periods. So we park rcu_cpu_kthread() until
1563 * the corresponding CPU is online.
1564 *
1565 * Return 1 if the kthread needs to stop, 0 otherwise.
1566 *
1567 * Caller must disable bh. This function can momentarily enable it.
1568 */
1569static int rcu_cpu_kthread_should_stop(int cpu)
1570{
1571 while (cpu_is_offline(cpu) ||
1572 !cpumask_equal(&current->cpus_allowed, cpumask_of(cpu)) ||
1573 smp_processor_id() != cpu) {
1574 if (kthread_should_stop())
1575 return 1;
1576 per_cpu(rcu_cpu_kthread_status, cpu) = RCU_KTHREAD_OFFCPU;
1577 per_cpu(rcu_cpu_kthread_cpu, cpu) = raw_smp_processor_id();
1578 local_bh_enable();
1579 schedule_timeout_uninterruptible(1);
1580 if (!cpumask_equal(&current->cpus_allowed, cpumask_of(cpu)))
1581 set_cpus_allowed_ptr(current, cpumask_of(cpu));
1582 local_bh_disable();
1583 }
1584 per_cpu(rcu_cpu_kthread_cpu, cpu) = cpu;
1585 return 0;
1586}
1587
1588/*
1589 * Per-CPU kernel thread that invokes RCU callbacks. This replaces the
1590 * earlier RCU softirq.
1591 */
1592static int rcu_cpu_kthread(void *arg)
1593{
1594 int cpu = (int)(long)arg;
1595 unsigned long flags;
1596 int spincnt = 0;
1597 unsigned int *statusp = &per_cpu(rcu_cpu_kthread_status, cpu);
1598 char work;
1599 char *workp = &per_cpu(rcu_cpu_has_work, cpu);
1600
1601 for (;;) {
1602 *statusp = RCU_KTHREAD_WAITING;
1603 rcu_wait(*workp != 0 || kthread_should_stop());
1604 local_bh_disable();
1605 if (rcu_cpu_kthread_should_stop(cpu)) {
1606 local_bh_enable();
1607 break;
1608 }
1609 *statusp = RCU_KTHREAD_RUNNING;
1610 per_cpu(rcu_cpu_kthread_loops, cpu)++;
1611 local_irq_save(flags);
1612 work = *workp;
1613 *workp = 0;
1614 local_irq_restore(flags);
1615 if (work)
1616 rcu_process_callbacks();
1617 local_bh_enable();
1618 if (*workp != 0)
1619 spincnt++;
1620 else
1621 spincnt = 0;
1622 if (spincnt > 10) {
1623 *statusp = RCU_KTHREAD_YIELDING;
1624 rcu_yield(rcu_cpu_kthread_timer, (unsigned long)cpu);
1625 spincnt = 0;
1626 }
1627 }
1628 *statusp = RCU_KTHREAD_STOPPED;
1629 return 0;
1630}
1631
1632/*
1633 * Spawn a per-CPU kthread, setting up affinity and priority.
1634 * Because the CPU hotplug lock is held, no other CPU will be attempting
1635 * to manipulate rcu_cpu_kthread_task. There might be another CPU
1636 * attempting to access it during boot, but the locking in kthread_bind()
1637 * will enforce sufficient ordering.
1638 */
1639static int __cpuinit rcu_spawn_one_cpu_kthread(int cpu)
1640{ 1469{
1641 struct sched_param sp; 1470 if (likely(!rsp->boost)) {
1642 struct task_struct *t; 1471 rcu_do_batch(rsp, rdp);
1643
1644 if (!rcu_kthreads_spawnable ||
1645 per_cpu(rcu_cpu_kthread_task, cpu) != NULL)
1646 return 0;
1647 t = kthread_create(rcu_cpu_kthread, (void *)(long)cpu, "rcuc%d", cpu);
1648 if (IS_ERR(t))
1649 return PTR_ERR(t);
1650 kthread_bind(t, cpu);
1651 per_cpu(rcu_cpu_kthread_cpu, cpu) = cpu;
1652 WARN_ON_ONCE(per_cpu(rcu_cpu_kthread_task, cpu) != NULL);
1653 per_cpu(rcu_cpu_kthread_task, cpu) = t;
1654 sp.sched_priority = RCU_KTHREAD_PRIO;
1655 sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
1656 return 0;
1657}
1658
1659/*
1660 * Per-rcu_node kthread, which is in charge of waking up the per-CPU
1661 * kthreads when needed. We ignore requests to wake up kthreads
1662 * for offline CPUs, which is OK because force_quiescent_state()
1663 * takes care of this case.
1664 */
1665static int rcu_node_kthread(void *arg)
1666{
1667 int cpu;
1668 unsigned long flags;
1669 unsigned long mask;
1670 struct rcu_node *rnp = (struct rcu_node *)arg;
1671 struct sched_param sp;
1672 struct task_struct *t;
1673
1674 for (;;) {
1675 rnp->node_kthread_status = RCU_KTHREAD_WAITING;
1676 rcu_wait(atomic_read(&rnp->wakemask) != 0);
1677 rnp->node_kthread_status = RCU_KTHREAD_RUNNING;
1678 raw_spin_lock_irqsave(&rnp->lock, flags);
1679 mask = atomic_xchg(&rnp->wakemask, 0);
1680 rcu_initiate_boost(rnp, flags); /* releases rnp->lock. */
1681 for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask >>= 1) {
1682 if ((mask & 0x1) == 0)
1683 continue;
1684 preempt_disable();
1685 t = per_cpu(rcu_cpu_kthread_task, cpu);
1686 if (!cpu_online(cpu) || t == NULL) {
1687 preempt_enable();
1688 continue;
1689 }
1690 per_cpu(rcu_cpu_has_work, cpu) = 1;
1691 sp.sched_priority = RCU_KTHREAD_PRIO;
1692 sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
1693 preempt_enable();
1694 }
1695 }
1696 /* NOTREACHED */
1697 rnp->node_kthread_status = RCU_KTHREAD_STOPPED;
1698 return 0;
1699}
1700
1701/*
1702 * Set the per-rcu_node kthread's affinity to cover all CPUs that are
1703 * served by the rcu_node in question. The CPU hotplug lock is still
1704 * held, so the value of rnp->qsmaskinit will be stable.
1705 *
1706 * We don't include outgoingcpu in the affinity set, use -1 if there is
1707 * no outgoing CPU. If there are no CPUs left in the affinity set,
1708 * this function allows the kthread to execute on any CPU.
1709 */
1710static void rcu_node_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu)
1711{
1712 cpumask_var_t cm;
1713 int cpu;
1714 unsigned long mask = rnp->qsmaskinit;
1715
1716 if (rnp->node_kthread_task == NULL)
1717 return;
1718 if (!alloc_cpumask_var(&cm, GFP_KERNEL))
1719 return; 1472 return;
1720 cpumask_clear(cm);
1721 for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask >>= 1)
1722 if ((mask & 0x1) && cpu != outgoingcpu)
1723 cpumask_set_cpu(cpu, cm);
1724 if (cpumask_weight(cm) == 0) {
1725 cpumask_setall(cm);
1726 for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++)
1727 cpumask_clear_cpu(cpu, cm);
1728 WARN_ON_ONCE(cpumask_weight(cm) == 0);
1729 } 1473 }
1730 set_cpus_allowed_ptr(rnp->node_kthread_task, cm); 1474 invoke_rcu_callbacks_kthread();
1731 rcu_boost_kthread_setaffinity(rnp, cm);
1732 free_cpumask_var(cm);
1733} 1475}
1734 1476
1735/* 1477static void invoke_rcu_core(void)
1736 * Spawn a per-rcu_node kthread, setting priority and affinity.
1737 * Called during boot before online/offline can happen, or, if
1738 * during runtime, with the main CPU-hotplug locks held. So only
1739 * one of these can be executing at a time.
1740 */
1741static int __cpuinit rcu_spawn_one_node_kthread(struct rcu_state *rsp,
1742 struct rcu_node *rnp)
1743{ 1478{
1744 unsigned long flags; 1479 raise_softirq(RCU_SOFTIRQ);
1745 int rnp_index = rnp - &rsp->node[0];
1746 struct sched_param sp;
1747 struct task_struct *t;
1748
1749 if (!rcu_kthreads_spawnable ||
1750 rnp->qsmaskinit == 0)
1751 return 0;
1752 if (rnp->node_kthread_task == NULL) {
1753 t = kthread_create(rcu_node_kthread, (void *)rnp,
1754 "rcun%d", rnp_index);
1755 if (IS_ERR(t))
1756 return PTR_ERR(t);
1757 raw_spin_lock_irqsave(&rnp->lock, flags);
1758 rnp->node_kthread_task = t;
1759 raw_spin_unlock_irqrestore(&rnp->lock, flags);
1760 sp.sched_priority = 99;
1761 sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
1762 }
1763 return rcu_spawn_one_boost_kthread(rsp, rnp, rnp_index);
1764} 1480}
1765 1481
1766static void rcu_wake_one_boost_kthread(struct rcu_node *rnp);
1767
1768/*
1769 * Spawn all kthreads -- called as soon as the scheduler is running.
1770 */
1771static int __init rcu_spawn_kthreads(void)
1772{
1773 int cpu;
1774 struct rcu_node *rnp;
1775 struct task_struct *t;
1776
1777 rcu_kthreads_spawnable = 1;
1778 for_each_possible_cpu(cpu) {
1779 per_cpu(rcu_cpu_has_work, cpu) = 0;
1780 if (cpu_online(cpu)) {
1781 (void)rcu_spawn_one_cpu_kthread(cpu);
1782 t = per_cpu(rcu_cpu_kthread_task, cpu);
1783 if (t)
1784 wake_up_process(t);
1785 }
1786 }
1787 rnp = rcu_get_root(rcu_state);
1788 (void)rcu_spawn_one_node_kthread(rcu_state, rnp);
1789 if (rnp->node_kthread_task)
1790 wake_up_process(rnp->node_kthread_task);
1791 if (NUM_RCU_NODES > 1) {
1792 rcu_for_each_leaf_node(rcu_state, rnp) {
1793 (void)rcu_spawn_one_node_kthread(rcu_state, rnp);
1794 t = rnp->node_kthread_task;
1795 if (t)
1796 wake_up_process(t);
1797 rcu_wake_one_boost_kthread(rnp);
1798 }
1799 }
1800 return 0;
1801}
1802early_initcall(rcu_spawn_kthreads);
1803
1804static void 1482static void
1805__call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu), 1483__call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
1806 struct rcu_state *rsp) 1484 struct rcu_state *rsp)
@@ -2207,44 +1885,6 @@ static void __cpuinit rcu_prepare_cpu(int cpu)
2207 rcu_preempt_init_percpu_data(cpu); 1885 rcu_preempt_init_percpu_data(cpu);
2208} 1886}
2209 1887
2210static void __cpuinit rcu_prepare_kthreads(int cpu)
2211{
2212 struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, cpu);
2213 struct rcu_node *rnp = rdp->mynode;
2214
2215 /* Fire up the incoming CPU's kthread and leaf rcu_node kthread. */
2216 if (rcu_kthreads_spawnable) {
2217 (void)rcu_spawn_one_cpu_kthread(cpu);
2218 if (rnp->node_kthread_task == NULL)
2219 (void)rcu_spawn_one_node_kthread(rcu_state, rnp);
2220 }
2221}
2222
2223/*
2224 * kthread_create() creates threads in TASK_UNINTERRUPTIBLE state,
2225 * but the RCU threads are woken on demand, and if demand is low this
2226 * could be a while triggering the hung task watchdog.
2227 *
2228 * In order to avoid this, poke all tasks once the CPU is fully
2229 * up and running.
2230 */
2231static void __cpuinit rcu_online_kthreads(int cpu)
2232{
2233 struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, cpu);
2234 struct rcu_node *rnp = rdp->mynode;
2235 struct task_struct *t;
2236
2237 t = per_cpu(rcu_cpu_kthread_task, cpu);
2238 if (t)
2239 wake_up_process(t);
2240
2241 t = rnp->node_kthread_task;
2242 if (t)
2243 wake_up_process(t);
2244
2245 rcu_wake_one_boost_kthread(rnp);
2246}
2247
2248/* 1888/*
2249 * Handle CPU online/offline notification events. 1889 * Handle CPU online/offline notification events.
2250 */ 1890 */
@@ -2262,7 +1902,6 @@ static int __cpuinit rcu_cpu_notify(struct notifier_block *self,
2262 rcu_prepare_kthreads(cpu); 1902 rcu_prepare_kthreads(cpu);
2263 break; 1903 break;
2264 case CPU_ONLINE: 1904 case CPU_ONLINE:
2265 rcu_online_kthreads(cpu);
2266 case CPU_DOWN_FAILED: 1905 case CPU_DOWN_FAILED:
2267 rcu_node_kthread_setaffinity(rnp, -1); 1906 rcu_node_kthread_setaffinity(rnp, -1);
2268 rcu_cpu_kthread_setrt(cpu, 1); 1907 rcu_cpu_kthread_setrt(cpu, 1);
@@ -2410,6 +2049,7 @@ void __init rcu_init(void)
2410 rcu_init_one(&rcu_sched_state, &rcu_sched_data); 2049 rcu_init_one(&rcu_sched_state, &rcu_sched_data);
2411 rcu_init_one(&rcu_bh_state, &rcu_bh_data); 2050 rcu_init_one(&rcu_bh_state, &rcu_bh_data);
2412 __rcu_init_preempt(); 2051 __rcu_init_preempt();
2052 open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
2413 2053
2414 /* 2054 /*
2415 * We don't need protection against CPU-hotplug here because 2055 * We don't need protection against CPU-hotplug here because
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 7b9a08b4aaea..01b2ccda26fb 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -369,6 +369,7 @@ struct rcu_state {
369 /* period because */ 369 /* period because */
370 /* force_quiescent_state() */ 370 /* force_quiescent_state() */
371 /* was running. */ 371 /* was running. */
372 u8 boost; /* Subject to priority boost. */
372 unsigned long gpnum; /* Current gp number. */ 373 unsigned long gpnum; /* Current gp number. */
373 unsigned long completed; /* # of last completed gp. */ 374 unsigned long completed; /* # of last completed gp. */
374 375
@@ -426,6 +427,7 @@ static int rcu_preempt_blocked_readers_cgp(struct rcu_node *rnp);
426#ifdef CONFIG_HOTPLUG_CPU 427#ifdef CONFIG_HOTPLUG_CPU
427static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp, 428static void rcu_report_unblock_qs_rnp(struct rcu_node *rnp,
428 unsigned long flags); 429 unsigned long flags);
430static void rcu_stop_cpu_kthread(int cpu);
429#endif /* #ifdef CONFIG_HOTPLUG_CPU */ 431#endif /* #ifdef CONFIG_HOTPLUG_CPU */
430static void rcu_print_detail_task_stall(struct rcu_state *rsp); 432static void rcu_print_detail_task_stall(struct rcu_state *rsp);
431static void rcu_print_task_stall(struct rcu_node *rnp); 433static void rcu_print_task_stall(struct rcu_node *rnp);
@@ -450,11 +452,19 @@ static void rcu_preempt_send_cbs_to_online(void);
450static void __init __rcu_init_preempt(void); 452static void __init __rcu_init_preempt(void);
451static void rcu_needs_cpu_flush(void); 453static void rcu_needs_cpu_flush(void);
452static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags); 454static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags);
455static void rcu_preempt_boost_start_gp(struct rcu_node *rnp);
456static void invoke_rcu_callbacks_kthread(void);
457#ifdef CONFIG_RCU_BOOST
458static void rcu_preempt_do_callbacks(void);
453static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, 459static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp,
454 cpumask_var_t cm); 460 cpumask_var_t cm);
455static void rcu_preempt_boost_start_gp(struct rcu_node *rnp);
456static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp, 461static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
457 struct rcu_node *rnp, 462 struct rcu_node *rnp,
458 int rnp_index); 463 int rnp_index);
464static void invoke_rcu_node_kthread(struct rcu_node *rnp);
465static void rcu_yield(void (*f)(unsigned long), unsigned long arg);
466#endif /* #ifdef CONFIG_RCU_BOOST */
467static void rcu_cpu_kthread_setrt(int cpu, int to_rt);
468static void __cpuinit rcu_prepare_kthreads(int cpu);
459 469
460#endif /* #ifndef RCU_TREE_NONCORE */ 470#endif /* #ifndef RCU_TREE_NONCORE */
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index c8bff3099a89..14dc7dd00902 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -602,6 +602,15 @@ static void rcu_preempt_process_callbacks(void)
602 &__get_cpu_var(rcu_preempt_data)); 602 &__get_cpu_var(rcu_preempt_data));
603} 603}
604 604
605#ifdef CONFIG_RCU_BOOST
606
607static void rcu_preempt_do_callbacks(void)
608{
609 rcu_do_batch(&rcu_preempt_state, &__get_cpu_var(rcu_preempt_data));
610}
611
612#endif /* #ifdef CONFIG_RCU_BOOST */
613
605/* 614/*
606 * Queue a preemptible-RCU callback for invocation after a grace period. 615 * Queue a preemptible-RCU callback for invocation after a grace period.
607 */ 616 */
@@ -1249,6 +1258,23 @@ static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags)
1249} 1258}
1250 1259
1251/* 1260/*
1261 * Wake up the per-CPU kthread to invoke RCU callbacks.
1262 */
1263static void invoke_rcu_callbacks_kthread(void)
1264{
1265 unsigned long flags;
1266
1267 local_irq_save(flags);
1268 __this_cpu_write(rcu_cpu_has_work, 1);
1269 if (__this_cpu_read(rcu_cpu_kthread_task) == NULL) {
1270 local_irq_restore(flags);
1271 return;
1272 }
1273 wake_up_process(__this_cpu_read(rcu_cpu_kthread_task));
1274 local_irq_restore(flags);
1275}
1276
1277/*
1252 * Set the affinity of the boost kthread. The CPU-hotplug locks are 1278 * Set the affinity of the boost kthread. The CPU-hotplug locks are
1253 * held, so no one should be messing with the existence of the boost 1279 * held, so no one should be messing with the existence of the boost
1254 * kthread. 1280 * kthread.
@@ -1288,6 +1314,7 @@ static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
1288 1314
1289 if (&rcu_preempt_state != rsp) 1315 if (&rcu_preempt_state != rsp)
1290 return 0; 1316 return 0;
1317 rsp->boost = 1;
1291 if (rnp->boost_kthread_task != NULL) 1318 if (rnp->boost_kthread_task != NULL)
1292 return 0; 1319 return 0;
1293 t = kthread_create(rcu_boost_kthread, (void *)rnp, 1320 t = kthread_create(rcu_boost_kthread, (void *)rnp,
@@ -1299,13 +1326,372 @@ static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp,
1299 raw_spin_unlock_irqrestore(&rnp->lock, flags); 1326 raw_spin_unlock_irqrestore(&rnp->lock, flags);
1300 sp.sched_priority = RCU_KTHREAD_PRIO; 1327 sp.sched_priority = RCU_KTHREAD_PRIO;
1301 sched_setscheduler_nocheck(t, SCHED_FIFO, &sp); 1328 sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
1329 wake_up_process(t); /* get to TASK_INTERRUPTIBLE quickly. */
1302 return 0; 1330 return 0;
1303} 1331}
1304 1332
1305static void __cpuinit rcu_wake_one_boost_kthread(struct rcu_node *rnp) 1333#ifdef CONFIG_HOTPLUG_CPU
1334
1335/*
1336 * Stop the RCU's per-CPU kthread when its CPU goes offline,.
1337 */
1338static void rcu_stop_cpu_kthread(int cpu)
1306{ 1339{
1307 if (rnp->boost_kthread_task) 1340 struct task_struct *t;
1308 wake_up_process(rnp->boost_kthread_task); 1341
1342 /* Stop the CPU's kthread. */
1343 t = per_cpu(rcu_cpu_kthread_task, cpu);
1344 if (t != NULL) {
1345 per_cpu(rcu_cpu_kthread_task, cpu) = NULL;
1346 kthread_stop(t);
1347 }
1348}
1349
1350#endif /* #ifdef CONFIG_HOTPLUG_CPU */
1351
1352static void rcu_kthread_do_work(void)
1353{
1354 rcu_do_batch(&rcu_sched_state, &__get_cpu_var(rcu_sched_data));
1355 rcu_do_batch(&rcu_bh_state, &__get_cpu_var(rcu_bh_data));
1356 rcu_preempt_do_callbacks();
1357}
1358
1359/*
1360 * Wake up the specified per-rcu_node-structure kthread.
1361 * Because the per-rcu_node kthreads are immortal, we don't need
1362 * to do anything to keep them alive.
1363 */
1364static void invoke_rcu_node_kthread(struct rcu_node *rnp)
1365{
1366 struct task_struct *t;
1367
1368 t = rnp->node_kthread_task;
1369 if (t != NULL)
1370 wake_up_process(t);
1371}
1372
1373/*
1374 * Set the specified CPU's kthread to run RT or not, as specified by
1375 * the to_rt argument. The CPU-hotplug locks are held, so the task
1376 * is not going away.
1377 */
1378static void rcu_cpu_kthread_setrt(int cpu, int to_rt)
1379{
1380 int policy;
1381 struct sched_param sp;
1382 struct task_struct *t;
1383
1384 t = per_cpu(rcu_cpu_kthread_task, cpu);
1385 if (t == NULL)
1386 return;
1387 if (to_rt) {
1388 policy = SCHED_FIFO;
1389 sp.sched_priority = RCU_KTHREAD_PRIO;
1390 } else {
1391 policy = SCHED_NORMAL;
1392 sp.sched_priority = 0;
1393 }
1394 sched_setscheduler_nocheck(t, policy, &sp);
1395}
1396
1397/*
1398 * Timer handler to initiate the waking up of per-CPU kthreads that
1399 * have yielded the CPU due to excess numbers of RCU callbacks.
1400 * We wake up the per-rcu_node kthread, which in turn will wake up
1401 * the booster kthread.
1402 */
1403static void rcu_cpu_kthread_timer(unsigned long arg)
1404{
1405 struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, arg);
1406 struct rcu_node *rnp = rdp->mynode;
1407
1408 atomic_or(rdp->grpmask, &rnp->wakemask);
1409 invoke_rcu_node_kthread(rnp);
1410}
1411
1412/*
1413 * Drop to non-real-time priority and yield, but only after posting a
1414 * timer that will cause us to regain our real-time priority if we
1415 * remain preempted. Either way, we restore our real-time priority
1416 * before returning.
1417 */
1418static void rcu_yield(void (*f)(unsigned long), unsigned long arg)
1419{
1420 struct sched_param sp;
1421 struct timer_list yield_timer;
1422
1423 setup_timer_on_stack(&yield_timer, f, arg);
1424 mod_timer(&yield_timer, jiffies + 2);
1425 sp.sched_priority = 0;
1426 sched_setscheduler_nocheck(current, SCHED_NORMAL, &sp);
1427 set_user_nice(current, 19);
1428 schedule();
1429 sp.sched_priority = RCU_KTHREAD_PRIO;
1430 sched_setscheduler_nocheck(current, SCHED_FIFO, &sp);
1431 del_timer(&yield_timer);
1432}
1433
1434/*
1435 * Handle cases where the rcu_cpu_kthread() ends up on the wrong CPU.
1436 * This can happen while the corresponding CPU is either coming online
1437 * or going offline. We cannot wait until the CPU is fully online
1438 * before starting the kthread, because the various notifier functions
1439 * can wait for RCU grace periods. So we park rcu_cpu_kthread() until
1440 * the corresponding CPU is online.
1441 *
1442 * Return 1 if the kthread needs to stop, 0 otherwise.
1443 *
1444 * Caller must disable bh. This function can momentarily enable it.
1445 */
1446static int rcu_cpu_kthread_should_stop(int cpu)
1447{
1448 while (cpu_is_offline(cpu) ||
1449 !cpumask_equal(&current->cpus_allowed, cpumask_of(cpu)) ||
1450 smp_processor_id() != cpu) {
1451 if (kthread_should_stop())
1452 return 1;
1453 per_cpu(rcu_cpu_kthread_status, cpu) = RCU_KTHREAD_OFFCPU;
1454 per_cpu(rcu_cpu_kthread_cpu, cpu) = raw_smp_processor_id();
1455 local_bh_enable();
1456 schedule_timeout_uninterruptible(1);
1457 if (!cpumask_equal(&current->cpus_allowed, cpumask_of(cpu)))
1458 set_cpus_allowed_ptr(current, cpumask_of(cpu));
1459 local_bh_disable();
1460 }
1461 per_cpu(rcu_cpu_kthread_cpu, cpu) = cpu;
1462 return 0;
1463}
1464
1465/*
1466 * Per-CPU kernel thread that invokes RCU callbacks. This replaces the
1467 * earlier RCU softirq.
1468 */
1469static int rcu_cpu_kthread(void *arg)
1470{
1471 int cpu = (int)(long)arg;
1472 unsigned long flags;
1473 int spincnt = 0;
1474 unsigned int *statusp = &per_cpu(rcu_cpu_kthread_status, cpu);
1475 char work;
1476 char *workp = &per_cpu(rcu_cpu_has_work, cpu);
1477
1478 for (;;) {
1479 *statusp = RCU_KTHREAD_WAITING;
1480 rcu_wait(*workp != 0 || kthread_should_stop());
1481 local_bh_disable();
1482 if (rcu_cpu_kthread_should_stop(cpu)) {
1483 local_bh_enable();
1484 break;
1485 }
1486 *statusp = RCU_KTHREAD_RUNNING;
1487 per_cpu(rcu_cpu_kthread_loops, cpu)++;
1488 local_irq_save(flags);
1489 work = *workp;
1490 *workp = 0;
1491 local_irq_restore(flags);
1492 if (work)
1493 rcu_kthread_do_work();
1494 local_bh_enable();
1495 if (*workp != 0)
1496 spincnt++;
1497 else
1498 spincnt = 0;
1499 if (spincnt > 10) {
1500 *statusp = RCU_KTHREAD_YIELDING;
1501 rcu_yield(rcu_cpu_kthread_timer, (unsigned long)cpu);
1502 spincnt = 0;
1503 }
1504 }
1505 *statusp = RCU_KTHREAD_STOPPED;
1506 return 0;
1507}
1508
1509/*
1510 * Spawn a per-CPU kthread, setting up affinity and priority.
1511 * Because the CPU hotplug lock is held, no other CPU will be attempting
1512 * to manipulate rcu_cpu_kthread_task. There might be another CPU
1513 * attempting to access it during boot, but the locking in kthread_bind()
1514 * will enforce sufficient ordering.
1515 *
1516 * Please note that we cannot simply refuse to wake up the per-CPU
1517 * kthread because kthreads are created in TASK_UNINTERRUPTIBLE state,
1518 * which can result in softlockup complaints if the task ends up being
1519 * idle for more than a couple of minutes.
1520 *
1521 * However, please note also that we cannot bind the per-CPU kthread to its
1522 * CPU until that CPU is fully online. We also cannot wait until the
1523 * CPU is fully online before we create its per-CPU kthread, as this would
1524 * deadlock the system when CPU notifiers tried waiting for grace
1525 * periods. So we bind the per-CPU kthread to its CPU only if the CPU
1526 * is online. If its CPU is not yet fully online, then the code in
1527 * rcu_cpu_kthread() will wait until it is fully online, and then do
1528 * the binding.
1529 */
1530static int __cpuinit rcu_spawn_one_cpu_kthread(int cpu)
1531{
1532 struct sched_param sp;
1533 struct task_struct *t;
1534
1535 if (!rcu_kthreads_spawnable ||
1536 per_cpu(rcu_cpu_kthread_task, cpu) != NULL)
1537 return 0;
1538 t = kthread_create(rcu_cpu_kthread, (void *)(long)cpu, "rcuc%d", cpu);
1539 if (IS_ERR(t))
1540 return PTR_ERR(t);
1541 if (cpu_online(cpu))
1542 kthread_bind(t, cpu);
1543 per_cpu(rcu_cpu_kthread_cpu, cpu) = cpu;
1544 WARN_ON_ONCE(per_cpu(rcu_cpu_kthread_task, cpu) != NULL);
1545 sp.sched_priority = RCU_KTHREAD_PRIO;
1546 sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
1547 per_cpu(rcu_cpu_kthread_task, cpu) = t;
1548 wake_up_process(t); /* Get to TASK_INTERRUPTIBLE quickly. */
1549 return 0;
1550}
1551
1552/*
1553 * Per-rcu_node kthread, which is in charge of waking up the per-CPU
1554 * kthreads when needed. We ignore requests to wake up kthreads
1555 * for offline CPUs, which is OK because force_quiescent_state()
1556 * takes care of this case.
1557 */
1558static int rcu_node_kthread(void *arg)
1559{
1560 int cpu;
1561 unsigned long flags;
1562 unsigned long mask;
1563 struct rcu_node *rnp = (struct rcu_node *)arg;
1564 struct sched_param sp;
1565 struct task_struct *t;
1566
1567 for (;;) {
1568 rnp->node_kthread_status = RCU_KTHREAD_WAITING;
1569 rcu_wait(atomic_read(&rnp->wakemask) != 0);
1570 rnp->node_kthread_status = RCU_KTHREAD_RUNNING;
1571 raw_spin_lock_irqsave(&rnp->lock, flags);
1572 mask = atomic_xchg(&rnp->wakemask, 0);
1573 rcu_initiate_boost(rnp, flags); /* releases rnp->lock. */
1574 for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask >>= 1) {
1575 if ((mask & 0x1) == 0)
1576 continue;
1577 preempt_disable();
1578 t = per_cpu(rcu_cpu_kthread_task, cpu);
1579 if (!cpu_online(cpu) || t == NULL) {
1580 preempt_enable();
1581 continue;
1582 }
1583 per_cpu(rcu_cpu_has_work, cpu) = 1;
1584 sp.sched_priority = RCU_KTHREAD_PRIO;
1585 sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
1586 preempt_enable();
1587 }
1588 }
1589 /* NOTREACHED */
1590 rnp->node_kthread_status = RCU_KTHREAD_STOPPED;
1591 return 0;
1592}
1593
1594/*
1595 * Set the per-rcu_node kthread's affinity to cover all CPUs that are
1596 * served by the rcu_node in question. The CPU hotplug lock is still
1597 * held, so the value of rnp->qsmaskinit will be stable.
1598 *
1599 * We don't include outgoingcpu in the affinity set, use -1 if there is
1600 * no outgoing CPU. If there are no CPUs left in the affinity set,
1601 * this function allows the kthread to execute on any CPU.
1602 */
1603static void rcu_node_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu)
1604{
1605 cpumask_var_t cm;
1606 int cpu;
1607 unsigned long mask = rnp->qsmaskinit;
1608
1609 if (rnp->node_kthread_task == NULL)
1610 return;
1611 if (!alloc_cpumask_var(&cm, GFP_KERNEL))
1612 return;
1613 cpumask_clear(cm);
1614 for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++, mask >>= 1)
1615 if ((mask & 0x1) && cpu != outgoingcpu)
1616 cpumask_set_cpu(cpu, cm);
1617 if (cpumask_weight(cm) == 0) {
1618 cpumask_setall(cm);
1619 for (cpu = rnp->grplo; cpu <= rnp->grphi; cpu++)
1620 cpumask_clear_cpu(cpu, cm);
1621 WARN_ON_ONCE(cpumask_weight(cm) == 0);
1622 }
1623 set_cpus_allowed_ptr(rnp->node_kthread_task, cm);
1624 rcu_boost_kthread_setaffinity(rnp, cm);
1625 free_cpumask_var(cm);
1626}
1627
1628/*
1629 * Spawn a per-rcu_node kthread, setting priority and affinity.
1630 * Called during boot before online/offline can happen, or, if
1631 * during runtime, with the main CPU-hotplug locks held. So only
1632 * one of these can be executing at a time.
1633 */
1634static int __cpuinit rcu_spawn_one_node_kthread(struct rcu_state *rsp,
1635 struct rcu_node *rnp)
1636{
1637 unsigned long flags;
1638 int rnp_index = rnp - &rsp->node[0];
1639 struct sched_param sp;
1640 struct task_struct *t;
1641
1642 if (!rcu_kthreads_spawnable ||
1643 rnp->qsmaskinit == 0)
1644 return 0;
1645 if (rnp->node_kthread_task == NULL) {
1646 t = kthread_create(rcu_node_kthread, (void *)rnp,
1647 "rcun%d", rnp_index);
1648 if (IS_ERR(t))
1649 return PTR_ERR(t);
1650 raw_spin_lock_irqsave(&rnp->lock, flags);
1651 rnp->node_kthread_task = t;
1652 raw_spin_unlock_irqrestore(&rnp->lock, flags);
1653 sp.sched_priority = 99;
1654 sched_setscheduler_nocheck(t, SCHED_FIFO, &sp);
1655 wake_up_process(t); /* get to TASK_INTERRUPTIBLE quickly. */
1656 }
1657 return rcu_spawn_one_boost_kthread(rsp, rnp, rnp_index);
1658}
1659
1660/*
1661 * Spawn all kthreads -- called as soon as the scheduler is running.
1662 */
1663static int __init rcu_spawn_kthreads(void)
1664{
1665 int cpu;
1666 struct rcu_node *rnp;
1667
1668 rcu_kthreads_spawnable = 1;
1669 for_each_possible_cpu(cpu) {
1670 per_cpu(rcu_cpu_has_work, cpu) = 0;
1671 if (cpu_online(cpu))
1672 (void)rcu_spawn_one_cpu_kthread(cpu);
1673 }
1674 rnp = rcu_get_root(rcu_state);
1675 (void)rcu_spawn_one_node_kthread(rcu_state, rnp);
1676 if (NUM_RCU_NODES > 1) {
1677 rcu_for_each_leaf_node(rcu_state, rnp)
1678 (void)rcu_spawn_one_node_kthread(rcu_state, rnp);
1679 }
1680 return 0;
1681}
1682early_initcall(rcu_spawn_kthreads);
1683
1684static void __cpuinit rcu_prepare_kthreads(int cpu)
1685{
1686 struct rcu_data *rdp = per_cpu_ptr(rcu_state->rda, cpu);
1687 struct rcu_node *rnp = rdp->mynode;
1688
1689 /* Fire up the incoming CPU's kthread and leaf rcu_node kthread. */
1690 if (rcu_kthreads_spawnable) {
1691 (void)rcu_spawn_one_cpu_kthread(cpu);
1692 if (rnp->node_kthread_task == NULL)
1693 (void)rcu_spawn_one_node_kthread(rcu_state, rnp);
1694 }
1309} 1695}
1310 1696
1311#else /* #ifdef CONFIG_RCU_BOOST */ 1697#else /* #ifdef CONFIG_RCU_BOOST */
@@ -1315,23 +1701,32 @@ static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags)
1315 raw_spin_unlock_irqrestore(&rnp->lock, flags); 1701 raw_spin_unlock_irqrestore(&rnp->lock, flags);
1316} 1702}
1317 1703
1318static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp, 1704static void invoke_rcu_callbacks_kthread(void)
1319 cpumask_var_t cm)
1320{ 1705{
1706 WARN_ON_ONCE(1);
1321} 1707}
1322 1708
1323static void rcu_preempt_boost_start_gp(struct rcu_node *rnp) 1709static void rcu_preempt_boost_start_gp(struct rcu_node *rnp)
1324{ 1710{
1325} 1711}
1326 1712
1327static int __cpuinit rcu_spawn_one_boost_kthread(struct rcu_state *rsp, 1713#ifdef CONFIG_HOTPLUG_CPU
1328 struct rcu_node *rnp, 1714
1329 int rnp_index) 1715static void rcu_stop_cpu_kthread(int cpu)
1716{
1717}
1718
1719#endif /* #ifdef CONFIG_HOTPLUG_CPU */
1720
1721static void rcu_node_kthread_setaffinity(struct rcu_node *rnp, int outgoingcpu)
1722{
1723}
1724
1725static void rcu_cpu_kthread_setrt(int cpu, int to_rt)
1330{ 1726{
1331 return 0;
1332} 1727}
1333 1728
1334static void __cpuinit rcu_wake_one_boost_kthread(struct rcu_node *rnp) 1729static void __cpuinit rcu_prepare_kthreads(int cpu)
1335{ 1730{
1336} 1731}
1337 1732
@@ -1509,7 +1904,7 @@ static DEFINE_PER_CPU(unsigned long, rcu_dyntick_holdoff);
1509 * 1904 *
1510 * Because it is not legal to invoke rcu_process_callbacks() with irqs 1905 * Because it is not legal to invoke rcu_process_callbacks() with irqs
1511 * disabled, we do one pass of force_quiescent_state(), then do a 1906 * disabled, we do one pass of force_quiescent_state(), then do a
1512 * invoke_rcu_cpu_kthread() to cause rcu_process_callbacks() to be invoked 1907 * invoke_rcu_core() to cause rcu_process_callbacks() to be invoked
1513 * later. The per-cpu rcu_dyntick_drain variable controls the sequencing. 1908 * later. The per-cpu rcu_dyntick_drain variable controls the sequencing.
1514 */ 1909 */
1515int rcu_needs_cpu(int cpu) 1910int rcu_needs_cpu(int cpu)
@@ -1560,7 +1955,7 @@ int rcu_needs_cpu(int cpu)
1560 1955
1561 /* If RCU callbacks are still pending, RCU still needs this CPU. */ 1956 /* If RCU callbacks are still pending, RCU still needs this CPU. */
1562 if (c) 1957 if (c)
1563 invoke_rcu_cpu_kthread(); 1958 invoke_rcu_core();
1564 return c; 1959 return c;
1565} 1960}
1566 1961
diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c
index 9678cc3650f5..4e144876dc68 100644
--- a/kernel/rcutree_trace.c
+++ b/kernel/rcutree_trace.c
@@ -46,6 +46,8 @@
46#define RCU_TREE_NONCORE 46#define RCU_TREE_NONCORE
47#include "rcutree.h" 47#include "rcutree.h"
48 48
49#ifdef CONFIG_RCU_BOOST
50
49DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status); 51DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_status);
50DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_cpu); 52DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_cpu);
51DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_loops); 53DECLARE_PER_CPU(unsigned int, rcu_cpu_kthread_loops);
@@ -58,6 +60,8 @@ static char convert_kthread_status(unsigned int kthread_status)
58 return "SRWOY"[kthread_status]; 60 return "SRWOY"[kthread_status];
59} 61}
60 62
63#endif /* #ifdef CONFIG_RCU_BOOST */
64
61static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp) 65static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
62{ 66{
63 if (!rdp->beenonline) 67 if (!rdp->beenonline)
@@ -76,7 +80,7 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
76 rdp->dynticks_fqs); 80 rdp->dynticks_fqs);
77#endif /* #ifdef CONFIG_NO_HZ */ 81#endif /* #ifdef CONFIG_NO_HZ */
78 seq_printf(m, " of=%lu ri=%lu", rdp->offline_fqs, rdp->resched_ipi); 82 seq_printf(m, " of=%lu ri=%lu", rdp->offline_fqs, rdp->resched_ipi);
79 seq_printf(m, " ql=%ld qs=%c%c%c%c kt=%d/%c/%d ktl=%x b=%ld", 83 seq_printf(m, " ql=%ld qs=%c%c%c%c",
80 rdp->qlen, 84 rdp->qlen,
81 ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] != 85 ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] !=
82 rdp->nxttail[RCU_NEXT_TAIL]], 86 rdp->nxttail[RCU_NEXT_TAIL]],
@@ -84,13 +88,16 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp)
84 rdp->nxttail[RCU_NEXT_READY_TAIL]], 88 rdp->nxttail[RCU_NEXT_READY_TAIL]],
85 ".W"[rdp->nxttail[RCU_DONE_TAIL] != 89 ".W"[rdp->nxttail[RCU_DONE_TAIL] !=
86 rdp->nxttail[RCU_WAIT_TAIL]], 90 rdp->nxttail[RCU_WAIT_TAIL]],
87 ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]], 91 ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]]);
92#ifdef CONFIG_RCU_BOOST
93 seq_printf(m, " kt=%d/%c/%d ktl=%x",
88 per_cpu(rcu_cpu_has_work, rdp->cpu), 94 per_cpu(rcu_cpu_has_work, rdp->cpu),
89 convert_kthread_status(per_cpu(rcu_cpu_kthread_status, 95 convert_kthread_status(per_cpu(rcu_cpu_kthread_status,
90 rdp->cpu)), 96 rdp->cpu)),
91 per_cpu(rcu_cpu_kthread_cpu, rdp->cpu), 97 per_cpu(rcu_cpu_kthread_cpu, rdp->cpu),
92 per_cpu(rcu_cpu_kthread_loops, rdp->cpu) & 0xffff, 98 per_cpu(rcu_cpu_kthread_loops, rdp->cpu) & 0xffff);
93 rdp->blimit); 99#endif /* #ifdef CONFIG_RCU_BOOST */
100 seq_printf(m, " b=%ld", rdp->blimit);
94 seq_printf(m, " ci=%lu co=%lu ca=%lu\n", 101 seq_printf(m, " ci=%lu co=%lu ca=%lu\n",
95 rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted); 102 rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
96} 103}
@@ -147,18 +154,21 @@ static void print_one_rcu_data_csv(struct seq_file *m, struct rcu_data *rdp)
147 rdp->dynticks_fqs); 154 rdp->dynticks_fqs);
148#endif /* #ifdef CONFIG_NO_HZ */ 155#endif /* #ifdef CONFIG_NO_HZ */
149 seq_printf(m, ",%lu,%lu", rdp->offline_fqs, rdp->resched_ipi); 156 seq_printf(m, ",%lu,%lu", rdp->offline_fqs, rdp->resched_ipi);
150 seq_printf(m, ",%ld,\"%c%c%c%c\",%d,\"%c\",%ld", rdp->qlen, 157 seq_printf(m, ",%ld,\"%c%c%c%c\"", rdp->qlen,
151 ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] != 158 ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] !=
152 rdp->nxttail[RCU_NEXT_TAIL]], 159 rdp->nxttail[RCU_NEXT_TAIL]],
153 ".R"[rdp->nxttail[RCU_WAIT_TAIL] != 160 ".R"[rdp->nxttail[RCU_WAIT_TAIL] !=
154 rdp->nxttail[RCU_NEXT_READY_TAIL]], 161 rdp->nxttail[RCU_NEXT_READY_TAIL]],
155 ".W"[rdp->nxttail[RCU_DONE_TAIL] != 162 ".W"[rdp->nxttail[RCU_DONE_TAIL] !=
156 rdp->nxttail[RCU_WAIT_TAIL]], 163 rdp->nxttail[RCU_WAIT_TAIL]],
157 ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]], 164 ".D"[&rdp->nxtlist != rdp->nxttail[RCU_DONE_TAIL]]);
165#ifdef CONFIG_RCU_BOOST
166 seq_printf(m, ",%d,\"%c\"",
158 per_cpu(rcu_cpu_has_work, rdp->cpu), 167 per_cpu(rcu_cpu_has_work, rdp->cpu),
159 convert_kthread_status(per_cpu(rcu_cpu_kthread_status, 168 convert_kthread_status(per_cpu(rcu_cpu_kthread_status,
160 rdp->cpu)), 169 rdp->cpu)));
161 rdp->blimit); 170#endif /* #ifdef CONFIG_RCU_BOOST */
171 seq_printf(m, ",%ld", rdp->blimit);
162 seq_printf(m, ",%lu,%lu,%lu\n", 172 seq_printf(m, ",%lu,%lu,%lu\n",
163 rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted); 173 rdp->n_cbs_invoked, rdp->n_cbs_orphaned, rdp->n_cbs_adopted);
164} 174}
@@ -169,7 +179,11 @@ static int show_rcudata_csv(struct seq_file *m, void *unused)
169#ifdef CONFIG_NO_HZ 179#ifdef CONFIG_NO_HZ
170 seq_puts(m, "\"dt\",\"dt nesting\",\"dt NMI nesting\",\"df\","); 180 seq_puts(m, "\"dt\",\"dt nesting\",\"dt NMI nesting\",\"df\",");
171#endif /* #ifdef CONFIG_NO_HZ */ 181#endif /* #ifdef CONFIG_NO_HZ */
172 seq_puts(m, "\"of\",\"ri\",\"ql\",\"b\",\"ci\",\"co\",\"ca\"\n"); 182 seq_puts(m, "\"of\",\"ri\",\"ql\",\"qs\"");
183#ifdef CONFIG_RCU_BOOST
184 seq_puts(m, "\"kt\",\"ktl\"");
185#endif /* #ifdef CONFIG_RCU_BOOST */
186 seq_puts(m, ",\"b\",\"ci\",\"co\",\"ca\"\n");
173#ifdef CONFIG_TREE_PREEMPT_RCU 187#ifdef CONFIG_TREE_PREEMPT_RCU
174 seq_puts(m, "\"rcu_preempt:\"\n"); 188 seq_puts(m, "\"rcu_preempt:\"\n");
175 PRINT_RCU_DATA(rcu_preempt_data, print_one_rcu_data_csv, m); 189 PRINT_RCU_DATA(rcu_preempt_data, print_one_rcu_data_csv, m);
diff --git a/kernel/softirq.c b/kernel/softirq.c
index 13960170cad4..40cf63ddd4b3 100644
--- a/kernel/softirq.c
+++ b/kernel/softirq.c
@@ -58,7 +58,7 @@ DEFINE_PER_CPU(struct task_struct *, ksoftirqd);
58 58
59char *softirq_to_name[NR_SOFTIRQS] = { 59char *softirq_to_name[NR_SOFTIRQS] = {
60 "HI", "TIMER", "NET_TX", "NET_RX", "BLOCK", "BLOCK_IOPOLL", 60 "HI", "TIMER", "NET_TX", "NET_RX", "BLOCK", "BLOCK_IOPOLL",
61 "TASKLET", "SCHED", "HRTIMER" 61 "TASKLET", "SCHED", "HRTIMER", "RCU"
62}; 62};
63 63
64/* 64/*
diff --git a/tools/perf/util/trace-event-parse.c b/tools/perf/util/trace-event-parse.c
index 1e88485c16a0..0a7ed5b5e281 100644
--- a/tools/perf/util/trace-event-parse.c
+++ b/tools/perf/util/trace-event-parse.c
@@ -2187,6 +2187,7 @@ static const struct flag flags[] = {
2187 { "TASKLET_SOFTIRQ", 6 }, 2187 { "TASKLET_SOFTIRQ", 6 },
2188 { "SCHED_SOFTIRQ", 7 }, 2188 { "SCHED_SOFTIRQ", 7 },
2189 { "HRTIMER_SOFTIRQ", 8 }, 2189 { "HRTIMER_SOFTIRQ", 8 },
2190 { "RCU_SOFTIRQ", 9 },
2190 2191
2191 { "HRTIMER_NORESTART", 0 }, 2192 { "HRTIMER_NORESTART", 0 },
2192 { "HRTIMER_RESTART", 1 }, 2193 { "HRTIMER_RESTART", 1 },
generated by cgit v1.2.2 (git 2.25.0) at 2024-11-06 21:54:58 -0500