diff options
Diffstat (limited to 'kernel/time')
| -rw-r--r-- | kernel/time/alarmtimer.c | 1 | ||||
| -rw-r--r-- | kernel/time/clockevents.c | 2 | ||||
| -rw-r--r-- | kernel/time/clocksource.c | 8 | ||||
| -rw-r--r-- | kernel/time/hrtimer.c | 2 | ||||
| -rw-r--r-- | kernel/time/test_udelay.c | 16 | ||||
| -rw-r--r-- | kernel/time/tick-broadcast-hrtimer.c | 1 | ||||
| -rw-r--r-- | kernel/time/tick-internal.h | 1 | ||||
| -rw-r--r-- | kernel/time/tick-sched.c | 98 | ||||
| -rw-r--r-- | kernel/time/timeconv.c | 11 | ||||
| -rw-r--r-- | kernel/time/timekeeping.c | 10 | ||||
| -rw-r--r-- | kernel/time/timer.c | 1111 | ||||
| -rw-r--r-- | kernel/time/timer_stats.c | 6 |
12 files changed, 741 insertions, 526 deletions
diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c index e840ed867a5d..c3aad685bbc0 100644 --- a/kernel/time/alarmtimer.c +++ b/kernel/time/alarmtimer.c @@ -30,7 +30,6 @@ * struct alarm_base - Alarm timer bases * @lock: Lock for syncrhonized access to the base * @timerqueue: Timerqueue head managing the list of events - * @timer: hrtimer used to schedule events while running * @gettime: Function to read the time correlating to the base * @base_clockid: clockid for the base */ diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c index a9b76a40319e..2c5bc77c0bb0 100644 --- a/kernel/time/clockevents.c +++ b/kernel/time/clockevents.c @@ -645,7 +645,7 @@ void tick_cleanup_dead_cpu(int cpu) #endif #ifdef CONFIG_SYSFS -struct bus_type clockevents_subsys = { +static struct bus_type clockevents_subsys = { .name = "clockevents", .dev_name = "clockevent", }; diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index 56ece145a814..6a5a310a1a53 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -669,10 +669,12 @@ static void clocksource_enqueue(struct clocksource *cs) struct list_head *entry = &clocksource_list; struct clocksource *tmp; - list_for_each_entry(tmp, &clocksource_list, list) + list_for_each_entry(tmp, &clocksource_list, list) { /* Keep track of the place, where to insert */ - if (tmp->rating >= cs->rating) - entry = &tmp->list; + if (tmp->rating < cs->rating) + break; + entry = &tmp->list; + } list_add(&cs->list, entry); } diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index e99df0ff1d42..d13c9aebf7a3 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -177,7 +177,7 @@ hrtimer_check_target(struct hrtimer *timer, struct hrtimer_clock_base *new_base) #endif } -#if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON) +#ifdef CONFIG_NO_HZ_COMMON static inline struct hrtimer_cpu_base *get_target_base(struct hrtimer_cpu_base *base, int pinned) diff --git a/kernel/time/test_udelay.c b/kernel/time/test_udelay.c index e622ba365a13..b0928ab3270f 100644 --- a/kernel/time/test_udelay.c +++ b/kernel/time/test_udelay.c @@ -43,13 +43,13 @@ static int udelay_test_single(struct seq_file *s, int usecs, uint32_t iters) int allowed_error_ns = usecs * 5; for (i = 0; i < iters; ++i) { - struct timespec ts1, ts2; + s64 kt1, kt2; int time_passed; - ktime_get_ts(&ts1); + kt1 = ktime_get_ns(); udelay(usecs); - ktime_get_ts(&ts2); - time_passed = timespec_to_ns(&ts2) - timespec_to_ns(&ts1); + kt2 = ktime_get_ns(); + time_passed = kt2 - kt1; if (i == 0 || time_passed < min) min = time_passed; @@ -87,11 +87,11 @@ static int udelay_test_show(struct seq_file *s, void *v) if (usecs > 0 && iters > 0) { return udelay_test_single(s, usecs, iters); } else if (usecs == 0) { - struct timespec ts; + struct timespec64 ts; - ktime_get_ts(&ts); - seq_printf(s, "udelay() test (lpj=%ld kt=%ld.%09ld)\n", - loops_per_jiffy, ts.tv_sec, ts.tv_nsec); + ktime_get_ts64(&ts); + seq_printf(s, "udelay() test (lpj=%ld kt=%lld.%09ld)\n", + loops_per_jiffy, (s64)ts.tv_sec, ts.tv_nsec); seq_puts(s, "usage:\n"); seq_puts(s, "echo USECS [ITERS] > " DEBUGFS_FILENAME "\n"); seq_puts(s, "cat " DEBUGFS_FILENAME "\n"); diff --git a/kernel/time/tick-broadcast-hrtimer.c b/kernel/time/tick-broadcast-hrtimer.c index 53d7184da0be..690b797f522e 100644 --- a/kernel/time/tick-broadcast-hrtimer.c +++ b/kernel/time/tick-broadcast-hrtimer.c @@ -75,6 +75,7 @@ static int bc_set_next(ktime_t expires, struct clock_event_device *bc) } static struct clock_event_device ce_broadcast_hrtimer = { + .name = "bc_hrtimer", .set_state_shutdown = bc_shutdown, .set_next_ktime = bc_set_next, .features = CLOCK_EVT_FEAT_ONESHOT | diff --git a/kernel/time/tick-internal.h b/kernel/time/tick-internal.h index 966a5a6fdd0a..f738251000fe 100644 --- a/kernel/time/tick-internal.h +++ b/kernel/time/tick-internal.h @@ -164,3 +164,4 @@ static inline void timers_update_migration(bool update_nohz) { } DECLARE_PER_CPU(struct hrtimer_cpu_base, hrtimer_bases); extern u64 get_next_timer_interrupt(unsigned long basej, u64 basem); +void timer_clear_idle(void); diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 536ada80f6dd..204fdc86863d 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -31,7 +31,7 @@ #include <trace/events/timer.h> /* - * Per cpu nohz control structure + * Per-CPU nohz control structure */ static DEFINE_PER_CPU(struct tick_sched, tick_cpu_sched); @@ -61,7 +61,7 @@ static void tick_do_update_jiffies64(ktime_t now) if (delta.tv64 < tick_period.tv64) return; - /* Reevalute with jiffies_lock held */ + /* Reevaluate with jiffies_lock held */ write_seqlock(&jiffies_lock); delta = ktime_sub(now, last_jiffies_update); @@ -116,8 +116,8 @@ static void tick_sched_do_timer(ktime_t now) #ifdef CONFIG_NO_HZ_COMMON /* * Check if the do_timer duty was dropped. We don't care about - * concurrency: This happens only when the cpu in charge went - * into a long sleep. If two cpus happen to assign themself to + * concurrency: This happens only when the CPU in charge went + * into a long sleep. If two CPUs happen to assign themselves to * this duty, then the jiffies update is still serialized by * jiffies_lock. */ @@ -349,7 +349,7 @@ void tick_nohz_dep_clear_signal(struct signal_struct *sig, enum tick_dep_bits bi /* * Re-evaluate the need for the tick as we switch the current task. * It might need the tick due to per task/process properties: - * perf events, posix cpu timers, ... + * perf events, posix CPU timers, ... */ void __tick_nohz_task_switch(void) { @@ -509,8 +509,8 @@ int tick_nohz_tick_stopped(void) * * In case the sched_tick was stopped on this CPU, we have to check if jiffies * must be updated. Otherwise an interrupt handler could use a stale jiffy - * value. We do this unconditionally on any cpu, as we don't know whether the - * cpu, which has the update task assigned is in a long sleep. + * value. We do this unconditionally on any CPU, as we don't know whether the + * CPU, which has the update task assigned is in a long sleep. */ static void tick_nohz_update_jiffies(ktime_t now) { @@ -526,7 +526,7 @@ static void tick_nohz_update_jiffies(ktime_t now) } /* - * Updates the per cpu time idle statistics counters + * Updates the per-CPU time idle statistics counters */ static void update_ts_time_stats(int cpu, struct tick_sched *ts, ktime_t now, u64 *last_update_time) @@ -566,12 +566,12 @@ static ktime_t tick_nohz_start_idle(struct tick_sched *ts) } /** - * get_cpu_idle_time_us - get the total idle time of a cpu + * get_cpu_idle_time_us - get the total idle time of a CPU * @cpu: CPU number to query * @last_update_time: variable to store update time in. Do not update * counters if NULL. * - * Return the cummulative idle time (since boot) for a given + * Return the cumulative idle time (since boot) for a given * CPU, in microseconds. * * This time is measured via accounting rather than sampling, @@ -607,12 +607,12 @@ u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time) EXPORT_SYMBOL_GPL(get_cpu_idle_time_us); /** - * get_cpu_iowait_time_us - get the total iowait time of a cpu + * get_cpu_iowait_time_us - get the total iowait time of a CPU * @cpu: CPU number to query * @last_update_time: variable to store update time in. Do not update * counters if NULL. * - * Return the cummulative iowait time (since boot) for a given + * Return the cumulative iowait time (since boot) for a given * CPU, in microseconds. * * This time is measured via accounting rather than sampling, @@ -700,6 +700,12 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts, delta = next_tick - basemono; if (delta <= (u64)TICK_NSEC) { tick.tv64 = 0; + + /* + * Tell the timer code that the base is not idle, i.e. undo + * the effect of get_next_timer_interrupt(): + */ + timer_clear_idle(); /* * We've not stopped the tick yet, and there's a timer in the * next period, so no point in stopping it either, bail. @@ -726,14 +732,14 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts, } /* - * If this cpu is the one which updates jiffies, then give up - * the assignment and let it be taken by the cpu which runs - * the tick timer next, which might be this cpu as well. If we + * If this CPU is the one which updates jiffies, then give up + * the assignment and let it be taken by the CPU which runs + * the tick timer next, which might be this CPU as well. If we * don't drop this here the jiffies might be stale and * do_timer() never invoked. Keep track of the fact that it - * was the one which had the do_timer() duty last. If this cpu + * was the one which had the do_timer() duty last. If this CPU * is the one which had the do_timer() duty last, we limit the - * sleep time to the timekeeping max_deferement value. + * sleep time to the timekeeping max_deferment value. * Otherwise we can sleep as long as we want. */ delta = timekeeping_max_deferment(); @@ -809,6 +815,12 @@ static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now) tick_do_update_jiffies64(now); cpu_load_update_nohz_stop(); + /* + * Clear the timer idle flag, so we avoid IPIs on remote queueing and + * the clock forward checks in the enqueue path: + */ + timer_clear_idle(); + calc_load_exit_idle(); touch_softlockup_watchdog_sched(); /* @@ -841,9 +853,9 @@ static void tick_nohz_full_update_tick(struct tick_sched *ts) static bool can_stop_idle_tick(int cpu, struct tick_sched *ts) { /* - * If this cpu is offline and it is the one which updates + * If this CPU is offline and it is the one which updates * jiffies, then give up the assignment and let it be taken by - * the cpu which runs the tick timer next. If we don't drop + * the CPU which runs the tick timer next. If we don't drop * this here the jiffies might be stale and do_timer() never * invoked. */ @@ -896,11 +908,10 @@ static void __tick_nohz_idle_enter(struct tick_sched *ts) ktime_t now, expires; int cpu = smp_processor_id(); - now = tick_nohz_start_idle(ts); - if (can_stop_idle_tick(cpu, ts)) { int was_stopped = ts->tick_stopped; + now = tick_nohz_start_idle(ts); ts->idle_calls++; expires = tick_nohz_stop_sched_tick(ts, now, cpu); @@ -933,11 +944,11 @@ void tick_nohz_idle_enter(void) WARN_ON_ONCE(irqs_disabled()); /* - * Update the idle state in the scheduler domain hierarchy - * when tick_nohz_stop_sched_tick() is called from the idle loop. - * State will be updated to busy during the first busy tick after - * exiting idle. - */ + * Update the idle state in the scheduler domain hierarchy + * when tick_nohz_stop_sched_tick() is called from the idle loop. + * State will be updated to busy during the first busy tick after + * exiting idle. + */ set_cpu_sd_state_idle(); local_irq_disable(); @@ -1092,35 +1103,6 @@ static void tick_nohz_switch_to_nohz(void) tick_nohz_activate(ts, NOHZ_MODE_LOWRES); } -/* - * When NOHZ is enabled and the tick is stopped, we need to kick the - * tick timer from irq_enter() so that the jiffies update is kept - * alive during long running softirqs. That's ugly as hell, but - * correctness is key even if we need to fix the offending softirq in - * the first place. - * - * Note, this is different to tick_nohz_restart. We just kick the - * timer and do not touch the other magic bits which need to be done - * when idle is left. - */ -static void tick_nohz_kick_tick(struct tick_sched *ts, ktime_t now) -{ -#if 0 - /* Switch back to 2.6.27 behaviour */ - ktime_t delta; - - /* - * Do not touch the tick device, when the next expiry is either - * already reached or less/equal than the tick period. - */ - delta = ktime_sub(hrtimer_get_expires(&ts->sched_timer), now); - if (delta.tv64 <= tick_period.tv64) - return; - - tick_nohz_restart(ts, now); -#endif -} - static inline void tick_nohz_irq_enter(void) { struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); @@ -1131,10 +1113,8 @@ static inline void tick_nohz_irq_enter(void) now = ktime_get(); if (ts->idle_active) tick_nohz_stop_idle(ts, now); - if (ts->tick_stopped) { + if (ts->tick_stopped) tick_nohz_update_jiffies(now); - tick_nohz_kick_tick(ts, now); - } } #else @@ -1211,7 +1191,7 @@ void tick_setup_sched_timer(void) hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); ts->sched_timer.function = tick_sched_timer; - /* Get the next period (per cpu) */ + /* Get the next period (per-CPU) */ hrtimer_set_expires(&ts->sched_timer, tick_init_jiffy_update()); /* Offset the tick to avert jiffies_lock contention. */ diff --git a/kernel/time/timeconv.c b/kernel/time/timeconv.c index 86628e755f38..7142580ad94f 100644 --- a/kernel/time/timeconv.c +++ b/kernel/time/timeconv.c @@ -67,20 +67,21 @@ static const unsigned short __mon_yday[2][13] = { #define SECS_PER_DAY (SECS_PER_HOUR * 24) /** - * time_to_tm - converts the calendar time to local broken-down time + * time64_to_tm - converts the calendar time to local broken-down time * * @totalsecs the number of seconds elapsed since 00:00:00 on January 1, 1970, * Coordinated Universal Time (UTC). * @offset offset seconds adding to totalsecs. * @result pointer to struct tm variable to receive broken-down time */ -void time_to_tm(time_t totalsecs, int offset, struct tm *result) +void time64_to_tm(time64_t totalsecs, int offset, struct tm *result) { long days, rem, y; + int remainder; const unsigned short *ip; - days = totalsecs / SECS_PER_DAY; - rem = totalsecs % SECS_PER_DAY; + days = div_s64_rem(totalsecs, SECS_PER_DAY, &remainder); + rem = remainder; rem += offset; while (rem < 0) { rem += SECS_PER_DAY; @@ -124,4 +125,4 @@ void time_to_tm(time_t totalsecs, int offset, struct tm *result) result->tm_mon = y; result->tm_mday = days + 1; } -EXPORT_SYMBOL(time_to_tm); +EXPORT_SYMBOL(time64_to_tm); diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index 255e225393ac..3b65746c7f15 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -480,10 +480,12 @@ static inline void old_vsyscall_fixup(struct timekeeper *tk) * users are removed, this can be killed. */ remainder = tk->tkr_mono.xtime_nsec & ((1ULL << tk->tkr_mono.shift) - 1); - tk->tkr_mono.xtime_nsec -= remainder; - tk->tkr_mono.xtime_nsec += 1ULL << tk->tkr_mono.shift; - tk->ntp_error += remainder << tk->ntp_error_shift; - tk->ntp_error -= (1ULL << tk->tkr_mono.shift) << tk->ntp_error_shift; + if (remainder != 0) { + tk->tkr_mono.xtime_nsec -= remainder; + tk->tkr_mono.xtime_nsec += 1ULL << tk->tkr_mono.shift; + tk->ntp_error += remainder << tk->ntp_error_shift; + tk->ntp_error -= (1ULL << tk->tkr_mono.shift) << tk->ntp_error_shift; + } } #else #define old_vsyscall_fixup(tk) diff --git a/kernel/time/timer.c b/kernel/time/timer.c index 3a95f9728778..cb9ab401e2d9 100644 --- a/kernel/time/timer.c +++ b/kernel/time/timer.c @@ -59,43 +59,153 @@ __visible u64 jiffies_64 __cacheline_aligned_in_smp = INITIAL_JIFFIES; EXPORT_SYMBOL(jiffies_64); /* - * per-CPU timer vector definitions: + * The timer wheel has LVL_DEPTH array levels. Each level provides an array of + * LVL_SIZE buckets. Each level is driven by its own clock and therefor each + * level has a different granularity. + * + * The level granularity is: LVL_CLK_DIV ^ lvl + * The level clock frequency is: HZ / (LVL_CLK_DIV ^ level) + * + * The array level of a newly armed timer depends on the relative expiry + * time. The farther the expiry time is away the higher the array level and + * therefor the granularity becomes. + * + * Contrary to the original timer wheel implementation, which aims for 'exact' + * expiry of the timers, this implementation removes the need for recascading + * the timers into the lower array levels. The previous 'classic' timer wheel + * implementation of the kernel already violated the 'exact' expiry by adding + * slack to the expiry time to provide batched expiration. The granularity + * levels provide implicit batching. + * + * This is an optimization of the original timer wheel implementation for the + * majority of the timer wheel use cases: timeouts. The vast majority of + * timeout timers (networking, disk I/O ...) are canceled before expiry. If + * the timeout expires it indicates that normal operation is disturbed, so it + * does not matter much whether the timeout comes with a slight delay. + * + * The only exception to this are networking timers with a small expiry + * time. They rely on the granularity. Those fit into the first wheel level, + * which has HZ granularity. + * + * We don't have cascading anymore. timers with a expiry time above the + * capacity of the last wheel level are force expired at the maximum timeout + * value of the last wheel level. From data sampling we know that the maximum + * value observed is 5 days (network connection tracking), so this should not + * be an issue. + * + * The currently chosen array constants values are a good compromise between + * array size and granularity. + * + * This results in the following granularity and range levels: + * + * HZ 1000 steps + * Level Offset Granularity Range + * 0 0 1 ms 0 ms - 63 ms + * 1 64 8 ms 64 ms - 511 ms + * 2 128 64 ms 512 ms - 4095 ms (512ms - ~4s) + * 3 192 512 ms 4096 ms - 32767 ms (~4s - ~32s) + * 4 256 4096 ms (~4s) 32768 ms - 262143 ms (~32s - ~4m) + * 5 320 32768 ms (~32s) 262144 ms - 2097151 ms (~4m - ~34m) + * 6 384 262144 ms (~4m) 2097152 ms - 16777215 ms (~34m - ~4h) + * 7 448 2097152 ms (~34m) 16777216 ms - 134217727 ms (~4h - ~1d) + * 8 512 16777216 ms (~4h) 134217728 ms - 1073741822 ms (~1d - ~12d) + * + * HZ 300 + * Level Offset Granularity Range + * 0 0 3 ms 0 ms - 210 ms + * 1 64 26 ms 213 ms - 1703 ms (213ms - ~1s) + * 2 128 213 ms 1706 ms - 13650 ms (~1s - ~13s) + * 3 192 1706 ms (~1s) 13653 ms - 109223 ms (~13s - ~1m) + * 4 256 13653 ms (~13s) 109226 ms - 873810 ms (~1m - ~14m) + * 5 320 109226 ms (~1m) 873813 ms - 6990503 ms (~14m - ~1h) + * 6 384 873813 ms (~14m) 6990506 ms - 55924050 ms (~1h - ~15h) + * 7 448 6990506 ms (~1h) 55924053 ms - 447392423 ms (~15h - ~5d) + * 8 512 55924053 ms (~15h) 447392426 ms - 3579139406 ms (~5d - ~41d) + * + * HZ 250 + * Level Offset Granularity Range + * 0 0 4 ms 0 ms - 255 ms + * 1 64 32 ms 256 ms - 2047 ms (256ms - ~2s) + * 2 128 256 ms 2048 ms - 16383 ms (~2s - ~16s) + * 3 192 2048 ms (~2s) 16384 ms - 131071 ms (~16s - ~2m) + * 4 256 16384 ms (~16s) 131072 ms - 1048575 ms (~2m - ~17m) + * 5 320 131072 ms (~2m) 1048576 ms - 8388607 ms (~17m - ~2h) + * 6 384 1048576 ms (~17m) 8388608 ms - 67108863 ms (~2h - ~18h) + * 7 448 8388608 ms (~2h) 67108864 ms - 536870911 ms (~18h - ~6d) + * 8 512 67108864 ms (~18h) 536870912 ms - 4294967288 ms (~6d - ~49d) + * + * HZ 100 + * Level Offset Granularity Range + * 0 0 10 ms 0 ms - 630 ms + * 1 64 80 ms 640 ms - 5110 ms (640ms - ~5s) + * 2 128 640 ms 5120 ms - 40950 ms (~5s - ~40s) + * 3 192 5120 ms (~5s) 40960 ms - 327670 ms (~40s - ~5m) + * 4 256 40960 ms (~40s) 327680 ms - 2621430 ms (~5m - ~43m) + * 5 320 327680 ms (~5m) 2621440 ms - 20971510 ms (~43m - ~5h) + * 6 384 2621440 ms (~43m) 20971520 ms - 167772150 ms (~5h - ~1d) + * 7 448 20971520 ms (~5h) 167772160 ms - 1342177270 ms (~1d - ~15d) */ -#define TVN_BITS (CONFIG_BASE_SMALL ? 4 : 6) -#define TVR_BITS (CONFIG_BASE_SMALL ? 6 : 8) -#define TVN_SIZE (1 << TVN_BITS) -#define TVR_SIZE (1 << TVR_BITS) -#define TVN_MASK (TVN_SIZE - 1) -#define TVR_MASK (TVR_SIZE - 1) -#define MAX_TVAL ((unsigned long)((1ULL << (TVR_BITS + 4*TVN_BITS)) - 1)) - -struct tvec { - struct hlist_head vec[TVN_SIZE]; -}; -struct tvec_root { - struct hlist_head vec[TVR_SIZE]; -}; +/* Clock divisor for the next level */ +#define LVL_CLK_SHIFT 3 +#define LVL_CLK_DIV (1UL << LVL_CLK_SHIFT) +#define LVL_CLK_MASK (LVL_CLK_DIV - 1) +#define LVL_SHIFT(n) ((n) * LVL_CLK_SHIFT) +#define LVL_GRAN(n) (1UL << LVL_SHIFT(n)) -struct tvec_base { - spinlock_t lock; - struct timer_list *running_timer; - unsigned long timer_jiffies; - unsigned long next_timer; - unsigned long active_timers; - unsigned long all_timers; - int cpu; - bool migration_enabled; - bool nohz_active; - struct tvec_root tv1; - struct tvec tv2; - struct tvec tv3; - struct tvec tv4; - struct tvec tv5; -} ____cacheline_aligned; +/* + * The time start value for each level to select the bucket at enqueue + * time. + */ +#define LVL_START(n) ((LVL_SIZE - 1) << (((n) - 1) * LVL_CLK_SHIFT)) + +/* Size of each clock level */ +#define LVL_BITS 6 +#define LVL_SIZE (1UL << LVL_BITS) +#define LVL_MASK (LVL_SIZE - 1) +#define LVL_OFFS(n) ((n) * LVL_SIZE) + +/* Level depth */ +#if HZ > 100 +# define LVL_DEPTH 9 +# else +# define LVL_DEPTH 8 +#endif + +/* The cutoff (max. capacity of the wheel) */ +#define WHEEL_TIMEOUT_CUTOFF (LVL_START(LVL_DEPTH)) +#define WHEEL_TIMEOUT_MAX (WHEEL_TIMEOUT_CUTOFF - LVL_GRAN(LVL_DEPTH - 1)) + +/* + * The resulting wheel size. If NOHZ is configured we allocate two + * wheels so we have a separate storage for the deferrable timers. + */ +#define WHEEL_SIZE (LVL_SIZE * LVL_DEPTH) + +#ifdef CONFIG_NO_HZ_COMMON +# define NR_BASES 2 +# define BASE_STD 0 +# define BASE_DEF 1 +#else +# define NR_BASES 1 +# define BASE_STD 0 +# define BASE_DEF 0 +#endif +struct timer_base { + spinlock_t lock; + struct timer_list *running_timer; + unsigned long clk; + unsigned long next_expiry; + unsigned int cpu; + bool migration_enabled; + bool nohz_active; + bool is_idle; + DECLARE_BITMAP(pending_map, WHEEL_SIZE); + struct hlist_head vectors[WHEEL_SIZE]; +} ____cacheline_aligned; -static DEFINE_PER_CPU(struct tvec_base, tvec_bases); +static DEFINE_PER_CPU(struct timer_base, timer_bases[NR_BASES]); #if defined(CONFIG_SMP) && defined(CONFIG_NO_HZ_COMMON) unsigned int sysctl_timer_migration = 1; @@ -106,15 +216,17 @@ void timers_update_migration(bool update_nohz) unsigned int cpu; /* Avoid the loop, if nothing to update */ - if (this_cpu_read(tvec_bases.migration_enabled) == on) + if (this_cpu_read(timer_bases[BASE_STD].migration_enabled) == on) return; for_each_possible_cpu(cpu) { - per_cpu(tvec_bases.migration_enabled, cpu) = on; + per_cpu(timer_bases[BASE_STD].migration_enabled, cpu) = on; + per_cpu(timer_bases[BASE_DEF].migration_enabled, cpu) = on; per_cpu(hrtimer_bases.migration_enabled, cpu) = on; if (!update_nohz) continue; - per_cpu(tvec_bases.nohz_active, cpu) = true; + per_cpu(timer_bases[BASE_STD].nohz_active, cpu) = true; + per_cpu(timer_bases[BASE_DEF].nohz_active, cpu) = true; per_cpu(hrtimer_bases.nohz_active, cpu) = true; } } @@ -133,20 +245,6 @@ int timer_migration_handler(struct ctl_table *table, int write, mutex_unlock(&mutex); return ret; } - -static inline struct tvec_base *get_target_base(struct tvec_base *base, - int pinned) -{ - if (pinned || !base->migration_enabled) - return this_cpu_ptr(&tvec_bases); - return per_cpu_ptr(&tvec_bases, get_nohz_timer_target()); -} -#else -static inline struct tvec_base *get_target_base(struct tvec_base *base, - int pinned) -{ - return this_cpu_ptr(&tvec_bases); -} #endif static unsigned long round_jiffies_common(unsigned long j, int cpu, @@ -351,101 +449,126 @@ unsigned long round_jiffies_up_relative(unsigned long j) } EXPORT_SYMBOL_GPL(round_jiffies_up_relative); -/** - * set_timer_slack - set the allowed slack for a timer - * @timer: the timer to be modified - * @slack_hz: the amount of time (in jiffies) allowed for rounding - * - * Set the amount of time, in jiffies, that a certain timer has - * in terms of slack. By setting this value, the timer subsystem - * will schedule the actual timer somewhere between - * the time mod_timer() asks for, and that time plus the slack. - * - * By setting the slack to -1, a percentage of the delay is used - * instead. - */ -void set_timer_slack(struct timer_list *timer, int slack_hz) + +static inline unsigned int timer_get_idx(struct timer_list *timer) { - timer->slack = slack_hz; + return (timer->flags & TIMER_ARRAYMASK) >> TIMER_ARRAYSHIFT; } -EXPORT_SYMBOL_GPL(set_timer_slack); -static void -__internal_add_timer(struct tvec_base *base, struct timer_list *timer) +static inline void timer_set_idx(struct timer_list *timer, unsigned int idx) { - unsigned long expires = timer->expires; - unsigned long idx = expires - base->timer_jiffies; - struct hlist_head *vec; + timer->flags = (timer->flags & ~TIMER_ARRAYMASK) | + idx << TIMER_ARRAYSHIFT; +} - if (idx < TVR_SIZE) { - int i = expires & TVR_MASK; - vec = base->tv1.vec + i; - } else if (idx < 1 << (TVR_BITS + TVN_BITS)) { - int i = (expires >> TVR_BITS) & TVN_MASK; - vec = base->tv2.vec + i; - } else if (idx < 1 << (TVR_BITS + 2 * TVN_BITS)) { - int i = (expires >> (TVR_BITS + TVN_BITS)) & TVN_MASK; - vec = base->tv3.vec + i; - } else if (idx < 1 << (TVR_BITS + 3 * TVN_BITS)) { - int i = (expires >> (TVR_BITS + 2 * TVN_BITS)) & TVN_MASK; - vec = base->tv4.vec + i; - } else if ((signed long) idx < 0) { - /* - * Can happen if you add a timer with expires == jiffies, - * or you set a timer to go off in the past - */ - vec = base->tv1.vec + (base->timer_jiffies & TVR_MASK); +/* + * Helper function to calculate the array index for a given expiry + * time. + */ +static inline unsigned calc_index(unsigned expires, unsigned lvl) +{ + expires = (expires + LVL_GRAN(lvl)) >> LVL_SHIFT(lvl); + return LVL_OFFS(lvl) + (expires & LVL_MASK); +} + +static int calc_wheel_index(unsigned long expires, unsigned long clk) +{ + unsigned long delta = expires - clk; + unsigned int idx; + + if (delta < LVL_START(1)) { + idx = calc_index(expires, 0); + } else if (delta < LVL_START(2)) { + idx = calc_index(expires, 1); + } else if (delta < LVL_START(3)) { + idx = calc_index(expires, 2); + } else if (delta < LVL_START(4)) { + idx = calc_index(expires, 3); + } else if (delta < LVL_START(5)) { + idx = calc_index(expires, 4); + } else if (delta < LVL_START(6)) { + idx = calc_index(expires, 5); + } else if (delta < LVL_START(7)) { + idx = calc_index(expires, 6); + } else if (LVL_DEPTH > 8 && delta < LVL_START(8)) { + idx = calc_index(expires, 7); + } else if ((long) delta < 0) { + idx = clk & LVL_MASK; } else { - int i; - /* If the timeout is larger than MAX_TVAL (on 64-bit - * architectures or with CONFIG_BASE_SMALL=1) then we - * use the maximum timeout. + /* + * Force expire obscene large timeouts to expire at the + * capacity limit of the wheel. */ - if (idx > MAX_TVAL) { - idx = MAX_TVAL; - expires = idx + base->timer_jiffies; - } - i = (expires >> (TVR_BITS + 3 * TVN_BITS)) & TVN_MASK; - vec = base->tv5.vec + i; + if (expires >= WHEEL_TIMEOUT_CUTOFF) + expires = WHEEL_TIMEOUT_MAX; + + idx = calc_index(expires, LVL_DEPTH - 1); } + return idx; +} - hlist_add_head(&timer->entry, vec); +/* + * Enqueue the timer into the hash bucket, mark it pending in + * the bitmap and store the index in the timer flags. + */ +static void enqueue_timer(struct timer_base *base, struct timer_list *timer, + unsigned int idx) +{ + hlist_add_head(&timer->entry, base->vectors + idx); + __set_bit(idx, base->pending_map); + timer_set_idx(timer, idx); } -static void internal_add_timer(struct tvec_base *base, struct timer_list *timer) +static void +__internal_add_timer(struct timer_base *base, struct timer_list *timer) { - /* Advance base->jiffies, if the base is empty */ - if (!base->all_timers++) - base->timer_jiffies = jiffies; + unsigned int idx; + + idx = calc_wheel_index(timer->expires, base->clk); + enqueue_timer(base, timer, idx); +} + +static void +trigger_dyntick_cpu(struct timer_base *base, struct timer_list *timer) +{ + if (!IS_ENABLED(CONFIG_NO_HZ_COMMON) || !base->nohz_active) + return; - __internal_add_timer(base, timer); /* - * Update base->active_timers and base->next_timer + * TODO: This wants some optimizing similar to the code below, but we + * will do that when we switch from push to pull for deferrable timers. */ - if (!(timer->flags & TIMER_DEFERRABLE)) { - if (!base->active_timers++ || - time_before(timer->expires, base->next_timer)) - base->next_timer = timer->expires; + if (timer->flags & TIMER_DEFERRABLE) { + if (tick_nohz_full_cpu(base->cpu)) + wake_up_nohz_cpu(base->cpu); + return; } /* - * Check whether the other CPU is in dynticks mode and needs - * to be triggered to reevaluate the timer wheel. - * We are protected against the other CPU fiddling - * with the timer by holding the timer base lock. This also - * makes sure that a CPU on the way to stop its tick can not - * evaluate the timer wheel. - * - * Spare the IPI for deferrable timers on idle targets though. - * The next busy ticks will take care of it. Except full dynticks - * require special care against races with idle_cpu(), lets deal - * with that later. + * We might have to IPI the remote CPU if the base is idle and the + * timer is not deferrable. If the other CPU is on the way to idle + * then it can't set base->is_idle as we hold the base lock: */ - if (base->nohz_active) { - if (!(timer->flags & TIMER_DEFERRABLE) || - tick_nohz_full_cpu(base->cpu)) - wake_up_nohz_cpu(base->cpu); - } + if (!base->is_idle) + return; + + /* Check whether this is the new first expiring timer: */ + if (time_after_eq(timer->expires, base->next_expiry)) + return; + + /* + * Set the next expiry time and kick the CPU so it can reevaluate the + * wheel: + */ + base->next_expiry = timer->expires; + wake_up_nohz_cpu(base->cpu); +} + +static void +internal_add_timer(struct timer_base *base, struct timer_list *timer) +{ + __internal_add_timer(base, timer); + trigger_dyntick_cpu(base, timer); } #ifdef CONFIG_TIMER_STATS @@ -666,7 +789,6 @@ static void do_init_timer(struct timer_list *timer, unsigned int flags, { timer->entry.pprev = NULL; timer->flags = flags | raw_smp_processor_id(); - timer->slack = -1; #ifdef CONFIG_TIMER_STATS timer->start_site = NULL; timer->start_pid = -1; @@ -706,54 +828,125 @@ static inline void detach_timer(struct timer_list *timer, bool clear_pending) entry->next = LIST_POISON2; } -static inline void -detach_expired_timer(struct timer_list *timer, struct tvec_base *base) -{ - detach_timer(timer, true); - if (!(timer->flags & TIMER_DEFERRABLE)) - base->active_timers--; - base->all_timers--; -} - -static int detach_if_pending(struct timer_list *timer, struct tvec_base *base, +static int detach_if_pending(struct timer_list *timer, struct timer_base *base, bool clear_pending) { + unsigned idx = timer_get_idx(timer); + if (!timer_pending(timer)) return 0; + if (hlist_is_singular_node(&timer->entry, base->vectors + idx)) + __clear_bit(idx, base->pending_map); + detach_timer(timer, clear_pending); - if (!(timer->flags & TIMER_DEFERRABLE)) { - base->active_timers--; - if (timer->expires == base->next_timer) - base->next_timer = base->timer_jiffies; - } - /* If this was the last timer, advance base->jiffies */ - if (!--base->all_timers) - base->timer_jiffies = jiffies; return 1; } +static inline struct timer_base *get_timer_cpu_base(u32 tflags, u32 cpu) +{ + struct timer_base *base = per_cpu_ptr(&timer_bases[BASE_STD], cpu); + + /* + * If the timer is deferrable and nohz is active then we need to use + * the deferrable base. + */ + if (IS_ENABLED(CONFIG_NO_HZ_COMMON) && base->nohz_active && + (tflags & TIMER_DEFERRABLE)) + base = per_cpu_ptr(&timer_bases[BASE_DEF], cpu); + return base; +} |