diff options
| -rw-r--r-- | Documentation/RCU/trace.txt | 4 | ||||
| -rw-r--r-- | include/linux/hardirq.h | 21 | ||||
| -rw-r--r-- | include/linux/rcupdate.h | 21 | ||||
| -rw-r--r-- | include/linux/tick.h | 11 | ||||
| -rw-r--r-- | include/trace/events/rcu.h | 10 | ||||
| -rw-r--r-- | kernel/rcutiny.c | 124 | ||||
| -rw-r--r-- | kernel/rcutree.c | 229 | ||||
| -rw-r--r-- | kernel/rcutree.h | 15 | ||||
| -rw-r--r-- | kernel/rcutree_trace.c | 10 | ||||
| -rw-r--r-- | kernel/time/tick-sched.c | 6 |
10 files changed, 297 insertions, 154 deletions
diff --git a/Documentation/RCU/trace.txt b/Documentation/RCU/trace.txt index aaf65f6c6cd..49587abfc2f 100644 --- a/Documentation/RCU/trace.txt +++ b/Documentation/RCU/trace.txt @@ -105,14 +105,10 @@ o "dt" is the current value of the dyntick counter that is incremented or one greater than the interrupt-nesting depth otherwise. The number after the second "/" is the NMI nesting depth. - This field is displayed only for CONFIG_NO_HZ kernels. - o "df" is the number of times that some other CPU has forced a quiescent state on behalf of this CPU due to this CPU being in dynticks-idle state. - This field is displayed only for CONFIG_NO_HZ kernels. - o "of" is the number of times that some other CPU has forced a quiescent state on behalf of this CPU due to this CPU being offline. In a perfect world, this might never happen, but it diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h index f743883f769..bb7f3097185 100644 --- a/include/linux/hardirq.h +++ b/include/linux/hardirq.h @@ -139,20 +139,7 @@ static inline void account_system_vtime(struct task_struct *tsk) extern void account_system_vtime(struct task_struct *tsk); #endif -#if defined(CONFIG_NO_HZ) #if defined(CONFIG_TINY_RCU) || defined(CONFIG_TINY_PREEMPT_RCU) -extern void rcu_enter_nohz(void); -extern void rcu_exit_nohz(void); - -static inline void rcu_irq_enter(void) -{ - rcu_exit_nohz(); -} - -static inline void rcu_irq_exit(void) -{ - rcu_enter_nohz(); -} static inline void rcu_nmi_enter(void) { @@ -163,17 +150,9 @@ static inline void rcu_nmi_exit(void) } #else -extern void rcu_irq_enter(void); -extern void rcu_irq_exit(void); extern void rcu_nmi_enter(void); extern void rcu_nmi_exit(void); #endif -#else -# define rcu_irq_enter() do { } while (0) -# define rcu_irq_exit() do { } while (0) -# define rcu_nmi_enter() do { } while (0) -# define rcu_nmi_exit() do { } while (0) -#endif /* #if defined(CONFIG_NO_HZ) */ /* * It is safe to do non-atomic ops on ->hardirq_context, diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h index 2cf4226ade7..cd1ad4b04c6 100644 --- a/include/linux/rcupdate.h +++ b/include/linux/rcupdate.h @@ -177,23 +177,10 @@ extern void rcu_sched_qs(int cpu); extern void rcu_bh_qs(int cpu); extern void rcu_check_callbacks(int cpu, int user); struct notifier_block; - -#ifdef CONFIG_NO_HZ - -extern void rcu_enter_nohz(void); -extern void rcu_exit_nohz(void); - -#else /* #ifdef CONFIG_NO_HZ */ - -static inline void rcu_enter_nohz(void) -{ -} - -static inline void rcu_exit_nohz(void) -{ -} - -#endif /* #else #ifdef CONFIG_NO_HZ */ +extern void rcu_idle_enter(void); +extern void rcu_idle_exit(void); +extern void rcu_irq_enter(void); +extern void rcu_irq_exit(void); /* * Infrastructure to implement the synchronize_() primitives in diff --git a/include/linux/tick.h b/include/linux/tick.h index b232ccc0ee2..ca40838fdfb 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -127,8 +127,15 @@ extern ktime_t tick_nohz_get_sleep_length(void); extern u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time); extern u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time); # else -static inline void tick_nohz_stop_sched_tick(int inidle) { } -static inline void tick_nohz_restart_sched_tick(void) { } +static inline void tick_nohz_stop_sched_tick(int inidle) +{ + if (inidle) + rcu_idle_enter(); +} +static inline void tick_nohz_restart_sched_tick(void) +{ + rcu_idle_exit(); +} static inline ktime_t tick_nohz_get_sleep_length(void) { ktime_t len = { .tv64 = NSEC_PER_SEC/HZ }; diff --git a/include/trace/events/rcu.h b/include/trace/events/rcu.h index 669fbd62ec2..e5771804c50 100644 --- a/include/trace/events/rcu.h +++ b/include/trace/events/rcu.h @@ -246,19 +246,21 @@ TRACE_EVENT(rcu_fqs, */ TRACE_EVENT(rcu_dyntick, - TP_PROTO(char *polarity), + TP_PROTO(char *polarity, int nesting), - TP_ARGS(polarity), + TP_ARGS(polarity, nesting), TP_STRUCT__entry( __field(char *, polarity) + __field(int, nesting) ), TP_fast_assign( __entry->polarity = polarity; + __entry->nesting = nesting; ), - TP_printk("%s", __entry->polarity) + TP_printk("%s %d", __entry->polarity, __entry->nesting) ); /* @@ -443,7 +445,7 @@ TRACE_EVENT(rcu_batch_end, #define trace_rcu_unlock_preempted_task(rcuname, gpnum, pid) do { } while (0) #define trace_rcu_quiescent_state_report(rcuname, gpnum, mask, qsmask, level, grplo, grphi, gp_tasks) do { } while (0) #define trace_rcu_fqs(rcuname, gpnum, cpu, qsevent) do { } while (0) -#define trace_rcu_dyntick(polarity) do { } while (0) +#define trace_rcu_dyntick(polarity, nesting) do { } while (0) #define trace_rcu_callback(rcuname, rhp, qlen) do { } while (0) #define trace_rcu_kfree_callback(rcuname, rhp, offset, qlen) do { } while (0) #define trace_rcu_batch_start(rcuname, qlen, blimit) do { } while (0) diff --git a/kernel/rcutiny.c b/kernel/rcutiny.c index 636af6d9c6e..3ab77bdc90c 100644 --- a/kernel/rcutiny.c +++ b/kernel/rcutiny.c @@ -53,31 +53,122 @@ static void __call_rcu(struct rcu_head *head, #include "rcutiny_plugin.h" -#ifdef CONFIG_NO_HZ +static long long rcu_dynticks_nesting = LLONG_MAX / 2; -static long rcu_dynticks_nesting = 1; +/* Common code for rcu_idle_enter() and rcu_irq_exit(), see kernel/rcutree.c. */ +static void rcu_idle_enter_common(void) +{ + if (rcu_dynticks_nesting) { + RCU_TRACE(trace_rcu_dyntick("--=", rcu_dynticks_nesting)); + return; + } + RCU_TRACE(trace_rcu_dyntick("Start", rcu_dynticks_nesting)); + if (!idle_cpu(smp_processor_id())) { + WARN_ON_ONCE(1); /* must be idle task! */ + RCU_TRACE(trace_rcu_dyntick("Error on entry: not idle task", + rcu_dynticks_nesting)); + ftrace_dump(DUMP_ALL); + } + rcu_sched_qs(0); /* implies rcu_bh_qsctr_inc(0) */ +} /* - * Enter dynticks-idle mode, which is an extended quiescent state - * if we have fully entered that mode (i.e., if the new value of - * dynticks_nesting is zero). + * Enter idle, which is an extended quiescent state if we have fully + * entered that mode (i.e., if the new value of dynticks_nesting is zero). */ -void rcu_enter_nohz(void) +void rcu_idle_enter(void) { - if (--rcu_dynticks_nesting == 0) - rcu_sched_qs(0); /* implies rcu_bh_qsctr_inc(0) */ + unsigned long flags; + + local_irq_save(flags); + rcu_dynticks_nesting = 0; + rcu_idle_enter_common(); + local_irq_restore(flags); } /* - * Exit dynticks-idle mode, so that we are no longer in an extended - * quiescent state. + * Exit an interrupt handler towards idle. + */ +void rcu_irq_exit(void) +{ + unsigned long flags; + + local_irq_save(flags); + rcu_dynticks_nesting--; + WARN_ON_ONCE(rcu_dynticks_nesting < 0); + rcu_idle_enter_common(); + local_irq_restore(flags); +} + +/* Common code for rcu_idle_exit() and rcu_irq_enter(), see kernel/rcutree.c. */ +static void rcu_idle_exit_common(long long oldval) +{ + if (oldval) { + RCU_TRACE(trace_rcu_dyntick("++=", rcu_dynticks_nesting)); + return; + } + RCU_TRACE(trace_rcu_dyntick("End", oldval)); + if (!idle_cpu(smp_processor_id())) { + WARN_ON_ONCE(1); /* must be idle task! */ + RCU_TRACE(trace_rcu_dyntick("Error on exit: not idle task", + oldval)); + ftrace_dump(DUMP_ALL); + } +} + +/* + * Exit idle, so that we are no longer in an extended quiescent state. */ -void rcu_exit_nohz(void) +void rcu_idle_exit(void) { + unsigned long flags; + long long oldval; + + local_irq_save(flags); + oldval = rcu_dynticks_nesting; + WARN_ON_ONCE(oldval != 0); + rcu_dynticks_nesting = LLONG_MAX / 2; + rcu_idle_exit_common(oldval); + local_irq_restore(flags); +} + +/* + * Enter an interrupt handler, moving away from idle. + */ +void rcu_irq_enter(void) +{ + unsigned long flags; + long long oldval; + + local_irq_save(flags); + oldval = rcu_dynticks_nesting; rcu_dynticks_nesting++; + WARN_ON_ONCE(rcu_dynticks_nesting == 0); + rcu_idle_exit_common(oldval); + local_irq_restore(flags); +} + +#ifdef CONFIG_PROVE_RCU + +/* + * Test whether RCU thinks that the current CPU is idle. + */ +int rcu_is_cpu_idle(void) +{ + return !rcu_dynticks_nesting; } -#endif /* #ifdef CONFIG_NO_HZ */ +#endif /* #ifdef CONFIG_PROVE_RCU */ + +/* + * Test whether the current CPU was interrupted from idle. Nested + * interrupts don't count, we must be running at the first interrupt + * level. + */ +int rcu_is_cpu_rrupt_from_idle(void) +{ + return rcu_dynticks_nesting <= 0; +} /* * Helper function for rcu_sched_qs() and rcu_bh_qs(). @@ -126,14 +217,13 @@ void rcu_bh_qs(int cpu) /* * Check to see if the scheduling-clock interrupt came from an extended - * quiescent state, and, if so, tell RCU about it. + * quiescent state, and, if so, tell RCU about it. This function must + * be called from hardirq context. It is normally called from the + * scheduling-clock interrupt. */ void rcu_check_callbacks(int cpu, int user) { - if (user || - (idle_cpu(cpu) && - !in_softirq() && - hardirq_count() <= (1 << HARDIRQ_SHIFT))) + if (user || rcu_is_cpu_rrupt_from_idle()) rcu_sched_qs(cpu); else if (!in_softirq()) rcu_bh_qs(cpu); diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 5d0b55a3a8c..1c40326724f 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -195,12 +195,10 @@ void rcu_note_context_switch(int cpu) } EXPORT_SYMBOL_GPL(rcu_note_context_switch); -#ifdef CONFIG_NO_HZ DEFINE_PER_CPU(struct rcu_dynticks, rcu_dynticks) = { - .dynticks_nesting = 1, + .dynticks_nesting = LLONG_MAX / 2, .dynticks = ATOMIC_INIT(1), }; -#endif /* #ifdef CONFIG_NO_HZ */ static int blimit = 10; /* Maximum callbacks per rcu_do_batch. */ static int qhimark = 10000; /* If this many pending, ignore blimit. */ @@ -328,11 +326,11 @@ static int rcu_implicit_offline_qs(struct rcu_data *rdp) return 1; } - /* If preemptible RCU, no point in sending reschedule IPI. */ - if (rdp->preemptible) - return 0; - - /* The CPU is online, so send it a reschedule IPI. */ + /* + * The CPU is online, so send it a reschedule IPI. This forces + * it through the scheduler, and (inefficiently) also handles cases + * where idle loops fail to inform RCU about the CPU being idle. + */ if (rdp->cpu != smp_processor_id()) smp_send_reschedule(rdp->cpu); else @@ -343,51 +341,97 @@ static int rcu_implicit_offline_qs(struct rcu_data *rdp) #endif /* #ifdef CONFIG_SMP */ -#ifdef CONFIG_NO_HZ +/* + * rcu_idle_enter_common - inform RCU that current CPU is moving towards idle + * + * If the new value of the ->dynticks_nesting counter now is zero, + * we really have entered idle, and must do the appropriate accounting. + * The caller must have disabled interrupts. + */ +static void rcu_idle_enter_common(struct rcu_dynticks *rdtp) +{ + if (rdtp->dynticks_nesting) { + trace_rcu_dyntick("--=", rdtp->dynticks_nesting); + return; + } + trace_rcu_dyntick("Start", rdtp->dynticks_nesting); + if (!idle_cpu(smp_processor_id())) { + WARN_ON_ONCE(1); /* must be idle task! */ + trace_rcu_dyntick("Error on entry: not idle task", + rdtp->dynticks_nesting); + ftrace_dump(DUMP_ALL); + } + /* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */ + smp_mb__before_atomic_inc(); /* See above. */ + atomic_inc(&rdtp->dynticks); + smp_mb__after_atomic_inc(); /* Force ordering with next sojourn. */ + WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1); +} /** - * rcu_enter_nohz - inform RCU that current CPU is entering nohz + * rcu_idle_enter - inform RCU that current CPU is entering idle * - * Enter nohz mode, in other words, -leave- the mode in which RCU + * Enter idle mode, in other words, -leave- the mode in which RCU * read-side critical sections can occur. (Though RCU read-side - * critical sections can occur in irq handlers in nohz mode, a possibility - * handled by rcu_irq_enter() and rcu_irq_exit()). + * critical sections can occur in irq handlers in idle, a possibility + * handled by irq_enter() and irq_exit().) + * + * We crowbar the ->dynticks_nesting field to zero to allow for + * the possibility of usermode upcalls having messed up our count + * of interrupt nesting level during the prior busy period. */ -void rcu_enter_nohz(void) +void rcu_idle_enter(void) { unsigned long flags; struct rcu_dynticks *rdtp; local_irq_save(flags); rdtp = &__get_cpu_var(rcu_dynticks); - if (--rdtp->dynticks_nesting) { - local_irq_restore(flags); - return; - } - trace_rcu_dyntick("Start"); - /* CPUs seeing atomic_inc() must see prior RCU read-side crit sects */ - smp_mb__before_atomic_inc(); /* See above. */ - atomic_inc(&rdtp->dynticks); - smp_mb__after_atomic_inc(); /* Force ordering with next sojourn. */ - WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1); + rdtp->dynticks_nesting = 0; + rcu_idle_enter_common(rdtp); local_irq_restore(flags); } -/* - * rcu_exit_nohz - inform RCU that current CPU is leaving nohz +/** + * rcu_irq_exit - inform RCU that current CPU is exiting irq towards idle + * + * Exit from an interrupt handler, which might possibly result in entering + * idle mode, in other words, leaving the mode in which read-side critical + * sections can occur. * - * Exit nohz mode, in other words, -enter- the mode in which RCU - * read-side critical sections normally occur. + * This code assumes that the idle loop never does anything that might + * result in unbalanced calls to irq_enter() and irq_exit(). If your + * architecture violates this assumption, RCU will give you what you + * deserve, good and hard. But very infrequently and irreproducibly. + * + * Use things like work queues to work around this limitation. + * + * You have been warned. */ -void rcu_exit_nohz(void) +void rcu_irq_exit(void) { unsigned long flags; struct rcu_dynticks *rdtp; local_irq_save(flags); rdtp = &__get_cpu_var(rcu_dynticks); - if (rdtp->dynticks_nesting++) { - local_irq_restore(flags); + rdtp->dynticks_nesting--; + WARN_ON_ONCE(rdtp->dynticks_nesting < 0); + rcu_idle_enter_common(rdtp); + local_irq_restore(flags); +} + +/* + * rcu_idle_exit_common - inform RCU that current CPU is moving away from idle + * + * If the new value of the ->dynticks_nesting counter was previously zero, + * we really have exited idle, and must do the appropriate accounting. + * The caller must have disabled interrupts. + */ +static void rcu_idle_exit_common(struct rcu_dynticks *rdtp, long long oldval) +{ + if (oldval) { + trace_rcu_dyntick("++=", rdtp->dynticks_nesting); return; } smp_mb__before_atomic_inc(); /* Force ordering w/previous sojourn. */ @@ -395,7 +439,71 @@ void rcu_exit_nohz(void) /* CPUs seeing atomic_inc() must see later RCU read-side crit sects */ smp_mb__after_atomic_inc(); /* See above. */ WARN_ON_ONCE(!(atomic_read(&rdtp->dynticks) & 0x1)); - trace_rcu_dyntick("End"); + trace_rcu_dyntick("End", oldval); + if (!idle_cpu(smp_processor_id())) { + WARN_ON_ONCE(1); /* must be idle task! */ + trace_rcu_dyntick("Error on exit: not idle task", oldval); + ftrace_dump(DUMP_ALL); + } +} + +/** + * rcu_idle_exit - inform RCU that current CPU is leaving idle + * + * Exit idle mode, in other words, -enter- the mode in which RCU + * read-side critical sections can occur. + * + * We crowbar the ->dynticks_nesting field to LLONG_MAX/2 to allow for + * the possibility of usermode upcalls messing up our count + * of interrupt nesting level during the busy period that is just + * now starting. + */ +void rcu_idle_exit(void) +{ + unsigned long flags; + struct rcu_dynticks *rdtp; + long long oldval; + + local_irq_save(flags); + rdtp = &__get_cpu_var(rcu_dynticks); + oldval = rdtp->dynticks_nesting; + WARN_ON_ONCE(oldval != 0); + rdtp->dynticks_nesting = LLONG_MAX / 2; + rcu_idle_exit_common(rdtp, oldval); + local_irq_restore(flags); +} + +/** + * rcu_irq_enter - inform RCU that current CPU is entering irq away from idle + * + * Enter an interrupt handler, which might possibly result in exiting + * idle mode, in other words, entering the mode in which read-side critical + * sections can occur. + * + * Note that the Linux kernel is fully capable of entering an interrupt + * handler that it never exits, for example when doing upcalls to + * user mode! This code assumes that the idle loop never does upcalls to + * user mode. If your architecture does do upcalls from the idle loop (or + * does anything else that results in unbalanced calls to the irq_enter() + * and irq_exit() functions), RCU will give you what you deserve, good + * and hard. But very infrequently and irreproducibly. + * + * Use things like work queues to work around this limitation. + * + * You have been warned. + */ +void rcu_irq_enter(void) +{ + unsigned long flags; + struct rcu_dynticks *rdtp; + long long oldval; + + local_irq_save(flags); + rdtp = &__get_cpu_var(rcu_dynticks); + oldval = rdtp->dynticks_nesting; + rdtp->dynticks_nesting++; + WARN_ON_ONCE(rdtp->dynticks_nesting == 0); + rcu_idle_exit_common(rdtp, oldval); local_irq_restore(flags); } @@ -442,27 +550,32 @@ void rcu_nmi_exit(void) WARN_ON_ONCE(atomic_read(&rdtp->dynticks) & 0x1); } +#ifdef CONFIG_PROVE_RCU + /** - * rcu_irq_enter - inform RCU of entry to hard irq context + * rcu_is_cpu_idle - see if RCU thinks that the current CPU is idle * - * If the CPU was idle with dynamic ticks active, this updates the - * rdtp->dynticks to let the RCU handling know that the CPU is active. + * If the current CPU is in its idle loop and is neither in an interrupt + * or NMI handler, return true. The caller must have at least disabled + * preemption. */ -void rcu_irq_enter(void) +int rcu_is_cpu_idle(void) { - rcu_exit_nohz(); + return (atomic_read(&__get_cpu_var(rcu_dynticks).dynticks) & 0x1) == 0; } +#endif /* #ifdef CONFIG_PROVE_RCU */ + /** - * rcu_irq_exit - inform RCU of exit from hard irq context + * rcu_is_cpu_rrupt_from_idle - see if idle or immediately interrupted from idle * - * If the CPU was idle with dynamic ticks active, update the rdp->dynticks - * to put let the RCU handling be aware that the CPU is going back to idle - * with no ticks. + * If the current CPU is idle or running at a first-level (not nested) + * interrupt from idle, return true. The caller must have at least + * disabled preemption. */ -void rcu_irq_exit(void) +int rcu_is_cpu_rrupt_from_idle(void) { - rcu_enter_nohz(); + return __get_cpu_var(rcu_dynticks).dynticks_nesting <= 1; } #ifdef CONFIG_SMP @@ -512,24 +625,6 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) #endif /* #ifdef CONFIG_SMP */ -#else /* #ifdef CONFIG_NO_HZ */ - -#ifdef CONFIG_SMP - -static int dyntick_save_progress_counter(struct rcu_data *rdp) -{ - return 0; -} - -static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) -{ - return rcu_implicit_offline_qs(rdp); -} - -#endif /* #ifdef CONFIG_SMP */ - -#endif /* #else #ifdef CONFIG_NO_HZ */ - int rcu_cpu_stall_suppress __read_mostly; static void record_gp_stall_check_time(struct rcu_state *rsp) @@ -1334,16 +1429,14 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp) * (user mode or idle loop for rcu, non-softirq execution for rcu_bh). * Also schedule RCU core processing. * - * This function must be called with hardirqs disabled. It is normally + * This function must be called from hardirq context. It is normally * invoked from the scheduling-clock interrupt. If rcu_pending returns * false, there is no point in invoking rcu_check_callbacks(). */ void rcu_check_callbacks(int cpu, int user) { trace_rcu_utilization("Start scheduler-tick"); - if (user || - (idle_cpu(cpu) && rcu_scheduler_active && - !in_softirq() && hardirq_count() <= (1 << HARDIRQ_SHIFT))) { + if (user || rcu_is_cpu_rrupt_from_idle()) { /* * Get here if this CPU took its interrupt from user @@ -1913,9 +2006,9 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp) for (i = 0; i < RCU_NEXT_SIZE; i++) rdp->nxttail[i] = &rdp->nxtlist; rdp->qlen = 0; -#ifdef CONFIG_NO_HZ rdp->dynticks = &per_cpu(rcu_dynticks, cpu); -#endif /* #ifdef CONFIG_NO_HZ */ + WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != LLONG_MAX / 2); + WARN_ON_ONCE(atomic_read(&rdp->dynticks->dynticks) != 1); rdp->cpu = cpu; rdp->rsp = rsp; raw_spin_unlock_irqrestore(&rnp->lock, flags); @@ -1942,6 +2035,8 @@ rcu_init_percpu_data(int cpu, struct rcu_state *rsp, int preemptible) rdp->qlen_last_fqs_check = 0; rdp->n_force_qs_snap = rsp->n_force_qs; rdp->blimit = blimit; + WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != LLONG_MAX / 2); + WARN_ON_ONCE((atomic_read(&rdp->dynticks->dynticks) & 0x1) != 1); raw_spin_unlock(&rnp->lock); /* irqs remain disabled. */ /* diff --git a/kernel/rcutree.h b/kernel/rcutree.h index 517f2f89a29..0963fa1541a 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -84,9 +84,10 @@ * Dynticks per-CPU state. */ struct rcu_dynticks { - int dynticks_nesting; /* Track irq/process nesting level. */ - int dynticks_nmi_nesting; /* Track NMI nesting level. */ - atomic_t dynticks; /* Even value for dynticks-idle, else odd. */ + long long dynticks_nesting; /* Track irq/process nesting level. */ + /* Process level is worth LLONG_MAX/2. */ + int dynticks_nmi_nesting; /* Track NMI nesting level. */ + atomic_t dynticks; /* Even value for idle, else odd. */ }; /* RCU's kthread states for tracing. */ @@ -274,16 +275,12 @@ struct rcu_data { /* did other CPU force QS recently? */ long blimit; /* Upper limit on a processed batch */ -#ifdef CONFIG_NO_HZ /* 3) dynticks interface. */ struct rcu_dynticks *dynticks; /* Shared per-CPU dynticks state. */ int dynticks_snap; /* Per-GP tracking for dynticks. */ -#endif /* #ifdef CONFIG_NO_HZ */ /* 4) reasons this CPU needed to be kicked by force_quiescent_state */ -#ifdef CONFIG_NO_HZ unsigned long dynticks_fqs; /* Kicked due to dynticks idle. */ -#endif /* #ifdef CONFIG_NO_HZ */ unsigned long offline_fqs; /* Kicked due to being offline. */ unsigned long resched_ipi; /* Sent a resched IPI. */ @@ -307,11 +304,7 @@ struct rcu_data { #define RCU_GP_INIT 1 /* Grace period being initialized. */ #define RCU_SAVE_DYNTICK 2 /* Need to scan dyntick state. */ #define RCU_FORCE_QS 3 /* Need to force quiescent state. */ -#ifdef CONFIG_NO_HZ #define RCU_SIGNAL_INIT RCU_SAVE_DYNTICK -#else /* #ifdef CONFIG_NO_HZ */ -#define RCU_SIGNAL_INIT RCU_FORCE_QS -#endif /* #else #ifdef CONFIG_NO_HZ */ #define RCU_JIFFIES_TILL_FORCE_QS 3 /* for rsp->jiffies_force_qs */ diff --git a/kernel/rcutree_trace.c b/kernel/rcutree_trace.c index 59c7bee4ce0..654cfe67f0d 100644 --- a/kernel/rcutree_trace.c +++ b/kernel/rcutree_trace.c @@ -67,13 +67,11 @@ static void print_one_rcu_data(struct seq_file *m, struct rcu_data *rdp) rdp->completed, rdp->gpnum, rdp->passed_quiesce, rdp->passed_quiesce_gpnum, rdp->qs_pending); -#ifdef CONFIG_NO_HZ - seq_printf(m, " dt=%d/%d/%d df=%lu", + seq_printf(m, " dt=%d/%llx/%d df=%lu", atomic_read(&rdp->dynticks->dynticks), rdp->dynticks->dynticks_nesting, rdp->dynticks->dynticks_nmi_nesting, rdp->dynticks_fqs); -#endif /* #ifdef CONFIG_NO_HZ */ seq_printf(m, " of=%lu ri=%lu", rdp->offline_fqs, rdp->resched_ipi); seq_printf(m, " ql=%ld qs=%c%c%c%c", rdp->qlen, @@ -141,13 +139,11 @@ static void print_one_rcu_data_csv(struct seq_file *m, struct rcu_data *rdp) rdp->completed, rdp->gpnum, rdp->passed_quiesce, rdp->passed_quiesce_gpnum, rdp->qs_pending); -#ifdef CONFIG_NO_HZ - seq_printf(m, ",%d,%d,%d,%lu", + seq_printf(m, ",%d,%llx,%d,%lu", atomic_read(&rdp->dynticks->dynticks), rdp->dynticks->dynticks_nesting, rdp->dynticks->dynticks_nmi_nesting, rdp->dynticks_fqs); -#endif /* #ifdef CONFIG_NO_HZ */ seq_printf(m, ",%lu,%lu", rdp->offline_fqs, rdp->resched_ipi); seq_printf(m, ",%ld,\"%c%c%c%c\"", rdp->qlen, ".N"[rdp->nxttail[RCU_NEXT_READY_TAIL] != @@ -171,9 +167,7 @@ static void print_one_rcu_data_csv(struct seq_file *m, struct rcu_data *rdp) static int show_rcudata_csv(struct seq_file *m, void *unused) { seq_puts(m, "\"CPU\",\"Online?\",\"c\",\"g\",\"pq\",\"pgp\",\"pq\","); -#ifdef CONFIG_NO_HZ seq_puts(m, "\"dt\",\"dt nesting\",\"dt NMI nesting\",\"df\","); -#endif /* #ifdef CONFIG_NO_HZ */ seq_puts(m, "\"of\",\"ri\",\"ql\",\"qs\""); #ifdef CONFIG_RCU_BOOST seq_puts(m, "\"kt\",\"ktl\""); diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 40420644d0b..5d9d23665f1 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -434,7 +434,6 @@ void tick_nohz_stop_sched_tick(int inidle) ts->idle_tick = hrtimer_get_expires(&ts->sched_timer); ts->tick_stopped = 1; ts->idle_jiffies = last_jiffies; - rcu_enter_nohz(); } ts->idle_sleeps++; @@ -473,6 +472,8 @@ out: ts->last_jiffies = last_jiffies; ts->sleep_length = ktime_sub(dev->next_event, now); end: + if (inidle) + rcu_idle_enter(); local_irq_restore(flags); } @@ -529,6 +530,7 @@ void tick_nohz_restart_sched_tick(void) ktime_t now; local_irq_disable(); + rcu_idle_exit(); if (ts->idle_active || (ts->inidle && ts->tick_stopped)) now = ktime_get(); @@ -543,8 +545,6 @@ void tick_nohz_restart_sched_tick(void) ts->inidle = 0; - rcu_exit_nohz(); - /* Update jiffies first */ select_nohz_load_balancer(0); tick_do_update_jiffies64(now); |