Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1 | /* |
| 2 | * linux/kernel/time/tick-sched.c |
| 3 | * |
| 4 | * Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de> |
| 5 | * Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar |
| 6 | * Copyright(C) 2006-2007 Timesys Corp., Thomas Gleixner |
| 7 | * |
| 8 | * No idle tick implementation for low and high resolution timers |
| 9 | * |
| 10 | * Started by: Thomas Gleixner and Ingo Molnar |
| 11 | * |
Pavel Machek | b10db7f | 2008-01-30 13:30:00 +0100 | [diff] [blame] | 12 | * Distribute under GPLv2. |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 13 | */ |
| 14 | #include <linux/cpu.h> |
| 15 | #include <linux/err.h> |
| 16 | #include <linux/hrtimer.h> |
| 17 | #include <linux/interrupt.h> |
| 18 | #include <linux/kernel_stat.h> |
| 19 | #include <linux/percpu.h> |
| 20 | #include <linux/profile.h> |
| 21 | #include <linux/sched.h> |
venkatesh.pallipadi@intel.com | 8083e4a | 2008-08-04 11:59:11 -0700 | [diff] [blame] | 22 | #include <linux/module.h> |
Frederic Weisbecker | 00b4295 | 2012-11-07 21:03:07 +0100 | [diff] [blame] | 23 | #include <linux/irq_work.h> |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 24 | |
David S. Miller | 9e203bc | 2007-02-24 22:10:13 -0800 | [diff] [blame] | 25 | #include <asm/irq_regs.h> |
| 26 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 27 | #include "tick-internal.h" |
| 28 | |
| 29 | /* |
| 30 | * Per cpu nohz control structure |
| 31 | */ |
Frederic Weisbecker | 33a5f62 | 2012-10-11 17:52:56 +0200 | [diff] [blame] | 32 | DEFINE_PER_CPU(struct tick_sched, tick_cpu_sched); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 33 | |
| 34 | /* |
John Stultz | d6ad418 | 2012-02-28 16:50:11 -0800 | [diff] [blame] | 35 | * The time, when the last jiffy update happened. Protected by jiffies_lock. |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 36 | */ |
| 37 | static ktime_t last_jiffies_update; |
| 38 | |
Ingo Molnar | 289f480 | 2007-02-16 01:28:15 -0800 | [diff] [blame] | 39 | struct tick_sched *tick_get_tick_sched(int cpu) |
| 40 | { |
| 41 | return &per_cpu(tick_cpu_sched, cpu); |
| 42 | } |
| 43 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 44 | /* |
| 45 | * Must be called with interrupts disabled ! |
| 46 | */ |
| 47 | static void tick_do_update_jiffies64(ktime_t now) |
| 48 | { |
| 49 | unsigned long ticks = 0; |
| 50 | ktime_t delta; |
| 51 | |
Ingo Molnar | 7a14ce1 | 2008-05-12 15:43:53 +0200 | [diff] [blame] | 52 | /* |
John Stultz | d6ad418 | 2012-02-28 16:50:11 -0800 | [diff] [blame] | 53 | * Do a quick check without holding jiffies_lock: |
Ingo Molnar | 7a14ce1 | 2008-05-12 15:43:53 +0200 | [diff] [blame] | 54 | */ |
| 55 | delta = ktime_sub(now, last_jiffies_update); |
| 56 | if (delta.tv64 < tick_period.tv64) |
| 57 | return; |
| 58 | |
John Stultz | d6ad418 | 2012-02-28 16:50:11 -0800 | [diff] [blame] | 59 | /* Reevalute with jiffies_lock held */ |
| 60 | write_seqlock(&jiffies_lock); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 61 | |
| 62 | delta = ktime_sub(now, last_jiffies_update); |
| 63 | if (delta.tv64 >= tick_period.tv64) { |
| 64 | |
| 65 | delta = ktime_sub(delta, tick_period); |
| 66 | last_jiffies_update = ktime_add(last_jiffies_update, |
| 67 | tick_period); |
| 68 | |
| 69 | /* Slow path for long timeouts */ |
| 70 | if (unlikely(delta.tv64 >= tick_period.tv64)) { |
| 71 | s64 incr = ktime_to_ns(tick_period); |
| 72 | |
| 73 | ticks = ktime_divns(delta, incr); |
| 74 | |
| 75 | last_jiffies_update = ktime_add_ns(last_jiffies_update, |
| 76 | incr * ticks); |
| 77 | } |
| 78 | do_timer(++ticks); |
Thomas Gleixner | 49d670f | 2008-09-22 18:56:01 +0200 | [diff] [blame] | 79 | |
| 80 | /* Keep the tick_next_period variable up to date */ |
| 81 | tick_next_period = ktime_add(last_jiffies_update, tick_period); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 82 | } |
John Stultz | d6ad418 | 2012-02-28 16:50:11 -0800 | [diff] [blame] | 83 | write_sequnlock(&jiffies_lock); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 84 | } |
| 85 | |
| 86 | /* |
| 87 | * Initialize and return retrieve the jiffies update. |
| 88 | */ |
| 89 | static ktime_t tick_init_jiffy_update(void) |
| 90 | { |
| 91 | ktime_t period; |
| 92 | |
John Stultz | d6ad418 | 2012-02-28 16:50:11 -0800 | [diff] [blame] | 93 | write_seqlock(&jiffies_lock); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 94 | /* Did we start the jiffies update yet ? */ |
| 95 | if (last_jiffies_update.tv64 == 0) |
| 96 | last_jiffies_update = tick_next_period; |
| 97 | period = last_jiffies_update; |
John Stultz | d6ad418 | 2012-02-28 16:50:11 -0800 | [diff] [blame] | 98 | write_sequnlock(&jiffies_lock); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 99 | return period; |
| 100 | } |
| 101 | |
Frederic Weisbecker | 5bb9622 | 2012-10-15 02:03:27 +0200 | [diff] [blame] | 102 | |
| 103 | static void tick_sched_do_timer(ktime_t now) |
| 104 | { |
| 105 | int cpu = smp_processor_id(); |
| 106 | |
| 107 | #ifdef CONFIG_NO_HZ |
| 108 | /* |
| 109 | * Check if the do_timer duty was dropped. We don't care about |
| 110 | * concurrency: This happens only when the cpu in charge went |
| 111 | * into a long sleep. If two cpus happen to assign themself to |
| 112 | * this duty, then the jiffies update is still serialized by |
Thomas Gleixner | 9c3f9e2 | 2012-11-21 20:31:52 +0100 | [diff] [blame] | 113 | * jiffies_lock. |
Frederic Weisbecker | 5bb9622 | 2012-10-15 02:03:27 +0200 | [diff] [blame] | 114 | */ |
| 115 | if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE)) |
| 116 | tick_do_timer_cpu = cpu; |
| 117 | #endif |
| 118 | |
| 119 | /* Check, if the jiffies need an update */ |
| 120 | if (tick_do_timer_cpu == cpu) |
| 121 | tick_do_update_jiffies64(now); |
| 122 | } |
| 123 | |
Frederic Weisbecker | 9e8f559 | 2012-10-15 02:43:03 +0200 | [diff] [blame] | 124 | static void tick_sched_handle(struct tick_sched *ts, struct pt_regs *regs) |
| 125 | { |
Frederic Weisbecker | 94a5714 | 2012-10-15 16:17:16 +0200 | [diff] [blame] | 126 | #ifdef CONFIG_NO_HZ |
Frederic Weisbecker | 9e8f559 | 2012-10-15 02:43:03 +0200 | [diff] [blame] | 127 | /* |
| 128 | * When we are idle and the tick is stopped, we have to touch |
| 129 | * the watchdog as we might not schedule for a really long |
| 130 | * time. This happens on complete idle SMP systems while |
| 131 | * waiting on the login prompt. We also increment the "start of |
| 132 | * idle" jiffy stamp so the idle accounting adjustment we do |
| 133 | * when we go busy again does not account too much ticks. |
| 134 | */ |
| 135 | if (ts->tick_stopped) { |
| 136 | touch_softlockup_watchdog(); |
| 137 | if (is_idle_task(current)) |
| 138 | ts->idle_jiffies++; |
| 139 | } |
Frederic Weisbecker | 94a5714 | 2012-10-15 16:17:16 +0200 | [diff] [blame] | 140 | #endif |
Frederic Weisbecker | 9e8f559 | 2012-10-15 02:43:03 +0200 | [diff] [blame] | 141 | update_process_times(user_mode(regs)); |
| 142 | profile_tick(CPU_PROFILING); |
| 143 | } |
| 144 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 145 | /* |
| 146 | * NOHZ - aka dynamic tick functionality |
| 147 | */ |
| 148 | #ifdef CONFIG_NO_HZ |
| 149 | /* |
| 150 | * NO HZ enabled ? |
| 151 | */ |
Paul E. McKenney | 9d2ad24 | 2012-06-24 10:15:02 -0700 | [diff] [blame] | 152 | int tick_nohz_enabled __read_mostly = 1; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 153 | |
| 154 | /* |
| 155 | * Enable / Disable tickless mode |
| 156 | */ |
| 157 | static int __init setup_tick_nohz(char *str) |
| 158 | { |
| 159 | if (!strcmp(str, "off")) |
| 160 | tick_nohz_enabled = 0; |
| 161 | else if (!strcmp(str, "on")) |
| 162 | tick_nohz_enabled = 1; |
| 163 | else |
| 164 | return 0; |
| 165 | return 1; |
| 166 | } |
| 167 | |
| 168 | __setup("nohz=", setup_tick_nohz); |
| 169 | |
| 170 | /** |
| 171 | * tick_nohz_update_jiffies - update jiffies when idle was interrupted |
| 172 | * |
| 173 | * Called from interrupt entry when the CPU was idle |
| 174 | * |
| 175 | * In case the sched_tick was stopped on this CPU, we have to check if jiffies |
| 176 | * must be updated. Otherwise an interrupt handler could use a stale jiffy |
| 177 | * value. We do this unconditionally on any cpu, as we don't know whether the |
| 178 | * cpu, which has the update task assigned is in a long sleep. |
| 179 | */ |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 180 | static void tick_nohz_update_jiffies(ktime_t now) |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 181 | { |
| 182 | int cpu = smp_processor_id(); |
| 183 | struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); |
| 184 | unsigned long flags; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 185 | |
Thomas Gleixner | 5df7fa1 | 2008-02-01 17:45:14 +0100 | [diff] [blame] | 186 | ts->idle_waketime = now; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 187 | |
| 188 | local_irq_save(flags); |
| 189 | tick_do_update_jiffies64(now); |
| 190 | local_irq_restore(flags); |
Ingo Molnar | 02ff375 | 2008-05-12 15:43:53 +0200 | [diff] [blame] | 191 | |
| 192 | touch_softlockup_watchdog(); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 193 | } |
| 194 | |
Arjan van de Ven | 595aac4 | 2010-05-09 08:22:45 -0700 | [diff] [blame] | 195 | /* |
| 196 | * Updates the per cpu time idle statistics counters |
| 197 | */ |
Arjan van de Ven | 8d63bf9 | 2010-05-09 08:24:03 -0700 | [diff] [blame] | 198 | static void |
Peter Zijlstra | 8c215bd | 2010-07-01 09:07:17 +0200 | [diff] [blame] | 199 | update_ts_time_stats(int cpu, struct tick_sched *ts, ktime_t now, u64 *last_update_time) |
Arjan van de Ven | 595aac4 | 2010-05-09 08:22:45 -0700 | [diff] [blame] | 200 | { |
| 201 | ktime_t delta; |
| 202 | |
Arjan van de Ven | 595aac4 | 2010-05-09 08:22:45 -0700 | [diff] [blame] | 203 | if (ts->idle_active) { |
| 204 | delta = ktime_sub(now, ts->idle_entrytime); |
Peter Zijlstra | 8c215bd | 2010-07-01 09:07:17 +0200 | [diff] [blame] | 205 | if (nr_iowait_cpu(cpu) > 0) |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 206 | ts->iowait_sleeptime = ktime_add(ts->iowait_sleeptime, delta); |
Michal Hocko | 6beea0c | 2011-08-24 09:37:48 +0200 | [diff] [blame] | 207 | else |
| 208 | ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta); |
Arjan van de Ven | 8c7b09f | 2010-05-09 08:23:23 -0700 | [diff] [blame] | 209 | ts->idle_entrytime = now; |
Arjan van de Ven | 595aac4 | 2010-05-09 08:22:45 -0700 | [diff] [blame] | 210 | } |
Arjan van de Ven | 8d63bf9 | 2010-05-09 08:24:03 -0700 | [diff] [blame] | 211 | |
Arjan van de Ven | e0e37c2 | 2010-05-09 08:24:39 -0700 | [diff] [blame] | 212 | if (last_update_time) |
Arjan van de Ven | 8d63bf9 | 2010-05-09 08:24:03 -0700 | [diff] [blame] | 213 | *last_update_time = ktime_to_us(now); |
| 214 | |
Arjan van de Ven | 595aac4 | 2010-05-09 08:22:45 -0700 | [diff] [blame] | 215 | } |
| 216 | |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 217 | static void tick_nohz_stop_idle(int cpu, ktime_t now) |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 218 | { |
| 219 | struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); |
| 220 | |
Peter Zijlstra | 8c215bd | 2010-07-01 09:07:17 +0200 | [diff] [blame] | 221 | update_ts_time_stats(cpu, ts, now, NULL); |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 222 | ts->idle_active = 0; |
Peter Zijlstra | 56c7426 | 2008-09-01 16:44:23 +0200 | [diff] [blame] | 223 | |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 224 | sched_clock_idle_wakeup_event(0); |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 225 | } |
| 226 | |
Peter Zijlstra | 8c215bd | 2010-07-01 09:07:17 +0200 | [diff] [blame] | 227 | static ktime_t tick_nohz_start_idle(int cpu, struct tick_sched *ts) |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 228 | { |
Michal Hocko | 430ee88 | 2011-12-01 17:00:22 +0100 | [diff] [blame] | 229 | ktime_t now = ktime_get(); |
Arjan van de Ven | 595aac4 | 2010-05-09 08:22:45 -0700 | [diff] [blame] | 230 | |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 231 | ts->idle_entrytime = now; |
| 232 | ts->idle_active = 1; |
Peter Zijlstra | 56c7426 | 2008-09-01 16:44:23 +0200 | [diff] [blame] | 233 | sched_clock_idle_sleep_event(); |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 234 | return now; |
| 235 | } |
| 236 | |
Arjan van de Ven | b1f724c | 2010-05-09 08:22:08 -0700 | [diff] [blame] | 237 | /** |
| 238 | * get_cpu_idle_time_us - get the total idle time of a cpu |
| 239 | * @cpu: CPU number to query |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 240 | * @last_update_time: variable to store update time in. Do not update |
| 241 | * counters if NULL. |
Arjan van de Ven | b1f724c | 2010-05-09 08:22:08 -0700 | [diff] [blame] | 242 | * |
| 243 | * Return the cummulative idle time (since boot) for a given |
Michal Hocko | 6beea0c | 2011-08-24 09:37:48 +0200 | [diff] [blame] | 244 | * CPU, in microseconds. |
Arjan van de Ven | b1f724c | 2010-05-09 08:22:08 -0700 | [diff] [blame] | 245 | * |
| 246 | * This time is measured via accounting rather than sampling, |
| 247 | * and is as accurate as ktime_get() is. |
| 248 | * |
| 249 | * This function returns -1 if NOHZ is not enabled. |
| 250 | */ |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 251 | u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time) |
| 252 | { |
| 253 | struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 254 | ktime_t now, idle; |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 255 | |
venkatesh.pallipadi@intel.com | 8083e4a | 2008-08-04 11:59:11 -0700 | [diff] [blame] | 256 | if (!tick_nohz_enabled) |
| 257 | return -1; |
| 258 | |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 259 | now = ktime_get(); |
| 260 | if (last_update_time) { |
| 261 | update_ts_time_stats(cpu, ts, now, last_update_time); |
| 262 | idle = ts->idle_sleeptime; |
| 263 | } else { |
| 264 | if (ts->idle_active && !nr_iowait_cpu(cpu)) { |
| 265 | ktime_t delta = ktime_sub(now, ts->idle_entrytime); |
venkatesh.pallipadi@intel.com | 8083e4a | 2008-08-04 11:59:11 -0700 | [diff] [blame] | 266 | |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 267 | idle = ktime_add(ts->idle_sleeptime, delta); |
| 268 | } else { |
| 269 | idle = ts->idle_sleeptime; |
| 270 | } |
| 271 | } |
| 272 | |
| 273 | return ktime_to_us(idle); |
| 274 | |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 275 | } |
venkatesh.pallipadi@intel.com | 8083e4a | 2008-08-04 11:59:11 -0700 | [diff] [blame] | 276 | EXPORT_SYMBOL_GPL(get_cpu_idle_time_us); |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 277 | |
Michal Hocko | 6beea0c | 2011-08-24 09:37:48 +0200 | [diff] [blame] | 278 | /** |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 279 | * get_cpu_iowait_time_us - get the total iowait time of a cpu |
| 280 | * @cpu: CPU number to query |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 281 | * @last_update_time: variable to store update time in. Do not update |
| 282 | * counters if NULL. |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 283 | * |
| 284 | * Return the cummulative iowait time (since boot) for a given |
| 285 | * CPU, in microseconds. |
| 286 | * |
| 287 | * This time is measured via accounting rather than sampling, |
| 288 | * and is as accurate as ktime_get() is. |
| 289 | * |
| 290 | * This function returns -1 if NOHZ is not enabled. |
| 291 | */ |
| 292 | u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time) |
| 293 | { |
| 294 | struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 295 | ktime_t now, iowait; |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 296 | |
| 297 | if (!tick_nohz_enabled) |
| 298 | return -1; |
| 299 | |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 300 | now = ktime_get(); |
| 301 | if (last_update_time) { |
| 302 | update_ts_time_stats(cpu, ts, now, last_update_time); |
| 303 | iowait = ts->iowait_sleeptime; |
| 304 | } else { |
| 305 | if (ts->idle_active && nr_iowait_cpu(cpu) > 0) { |
| 306 | ktime_t delta = ktime_sub(now, ts->idle_entrytime); |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 307 | |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 308 | iowait = ktime_add(ts->iowait_sleeptime, delta); |
| 309 | } else { |
| 310 | iowait = ts->iowait_sleeptime; |
| 311 | } |
| 312 | } |
| 313 | |
| 314 | return ktime_to_us(iowait); |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 315 | } |
| 316 | EXPORT_SYMBOL_GPL(get_cpu_iowait_time_us); |
| 317 | |
Frederic Weisbecker | 84bf1bc | 2011-08-01 01:25:38 +0200 | [diff] [blame] | 318 | static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts, |
| 319 | ktime_t now, int cpu) |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 320 | { |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 321 | unsigned long seq, last_jiffies, next_jiffies, delta_jiffies; |
Frederic Weisbecker | 84bf1bc | 2011-08-01 01:25:38 +0200 | [diff] [blame] | 322 | ktime_t last_update, expires, ret = { .tv64 = 0 }; |
Paul E. McKenney | aa9b1630 | 2012-05-10 16:41:44 -0700 | [diff] [blame] | 323 | unsigned long rcu_delta_jiffies; |
Len Brown | 4f86d3a | 2007-10-03 18:58:00 -0400 | [diff] [blame] | 324 | struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev; |
Jon Hunter | 9896246 | 2009-08-18 12:45:10 -0500 | [diff] [blame] | 325 | u64 time_delta; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 326 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 327 | /* Read jiffies and the time when jiffies were updated last */ |
| 328 | do { |
John Stultz | d6ad418 | 2012-02-28 16:50:11 -0800 | [diff] [blame] | 329 | seq = read_seqbegin(&jiffies_lock); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 330 | last_update = last_jiffies_update; |
| 331 | last_jiffies = jiffies; |
Thomas Gleixner | 2718501 | 2009-11-12 22:12:06 +0100 | [diff] [blame] | 332 | time_delta = timekeeping_max_deferment(); |
John Stultz | d6ad418 | 2012-02-28 16:50:11 -0800 | [diff] [blame] | 333 | } while (read_seqretry(&jiffies_lock, seq)); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 334 | |
Frederic Weisbecker | 74876a9 | 2012-10-12 18:00:23 +0200 | [diff] [blame] | 335 | if (rcu_needs_cpu(cpu, &rcu_delta_jiffies) || |
Frederic Weisbecker | 00b4295 | 2012-11-07 21:03:07 +0100 | [diff] [blame] | 336 | arch_needs_cpu(cpu) || irq_work_needs_cpu()) { |
Martin Schwidefsky | 3c5d92a | 2009-09-29 14:25:16 +0200 | [diff] [blame] | 337 | next_jiffies = last_jiffies + 1; |
Ingo Molnar | 6ba9b34 | 2007-02-19 18:11:56 +0000 | [diff] [blame] | 338 | delta_jiffies = 1; |
Martin Schwidefsky | 3c5d92a | 2009-09-29 14:25:16 +0200 | [diff] [blame] | 339 | } else { |
| 340 | /* Get the next timer wheel timer */ |
| 341 | next_jiffies = get_next_timer_interrupt(last_jiffies); |
| 342 | delta_jiffies = next_jiffies - last_jiffies; |
Paul E. McKenney | aa9b1630 | 2012-05-10 16:41:44 -0700 | [diff] [blame] | 343 | if (rcu_delta_jiffies < delta_jiffies) { |
| 344 | next_jiffies = last_jiffies + rcu_delta_jiffies; |
| 345 | delta_jiffies = rcu_delta_jiffies; |
| 346 | } |
Martin Schwidefsky | 3c5d92a | 2009-09-29 14:25:16 +0200 | [diff] [blame] | 347 | } |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 348 | /* |
| 349 | * Do not stop the tick, if we are only one off |
| 350 | * or if the cpu is required for rcu |
| 351 | */ |
Ingo Molnar | 6ba9b34 | 2007-02-19 18:11:56 +0000 | [diff] [blame] | 352 | if (!ts->tick_stopped && delta_jiffies == 1) |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 353 | goto out; |
| 354 | |
| 355 | /* Schedule the tick, if we are at least one jiffie off */ |
| 356 | if ((long)delta_jiffies >= 1) { |
| 357 | |
Woodruff, Richard | 0014744 | 2008-12-01 14:18:11 -0800 | [diff] [blame] | 358 | /* |
Woodruff, Richard | 0014744 | 2008-12-01 14:18:11 -0800 | [diff] [blame] | 359 | * If this cpu is the one which updates jiffies, then |
| 360 | * give up the assignment and let it be taken by the |
| 361 | * cpu which runs the tick timer next, which might be |
| 362 | * this cpu as well. If we don't drop this here the |
| 363 | * jiffies might be stale and do_timer() never |
Thomas Gleixner | 2718501 | 2009-11-12 22:12:06 +0100 | [diff] [blame] | 364 | * invoked. Keep track of the fact that it was the one |
| 365 | * which had the do_timer() duty last. If this cpu is |
| 366 | * the one which had the do_timer() duty last, we |
| 367 | * limit the sleep time to the timekeeping |
| 368 | * max_deferement value which we retrieved |
| 369 | * above. Otherwise we can sleep as long as we want. |
Woodruff, Richard | 0014744 | 2008-12-01 14:18:11 -0800 | [diff] [blame] | 370 | */ |
Thomas Gleixner | 2718501 | 2009-11-12 22:12:06 +0100 | [diff] [blame] | 371 | if (cpu == tick_do_timer_cpu) { |
Woodruff, Richard | 0014744 | 2008-12-01 14:18:11 -0800 | [diff] [blame] | 372 | tick_do_timer_cpu = TICK_DO_TIMER_NONE; |
Thomas Gleixner | 2718501 | 2009-11-12 22:12:06 +0100 | [diff] [blame] | 373 | ts->do_timer_last = 1; |
| 374 | } else if (tick_do_timer_cpu != TICK_DO_TIMER_NONE) { |
| 375 | time_delta = KTIME_MAX; |
| 376 | ts->do_timer_last = 0; |
| 377 | } else if (!ts->do_timer_last) { |
| 378 | time_delta = KTIME_MAX; |
| 379 | } |
| 380 | |
| 381 | /* |
Jon Hunter | 9896246 | 2009-08-18 12:45:10 -0500 | [diff] [blame] | 382 | * calculate the expiry time for the next timer wheel |
| 383 | * timer. delta_jiffies >= NEXT_TIMER_MAX_DELTA signals |
| 384 | * that there is no timer pending or at least extremely |
| 385 | * far into the future (12 days for HZ=1000). In this |
| 386 | * case we set the expiry to the end of time. |
| 387 | */ |
| 388 | if (likely(delta_jiffies < NEXT_TIMER_MAX_DELTA)) { |
| 389 | /* |
| 390 | * Calculate the time delta for the next timer event. |
| 391 | * If the time delta exceeds the maximum time delta |
| 392 | * permitted by the current clocksource then adjust |
| 393 | * the time delta accordingly to ensure the |
| 394 | * clocksource does not wrap. |
| 395 | */ |
| 396 | time_delta = min_t(u64, time_delta, |
| 397 | tick_period.tv64 * delta_jiffies); |
Jon Hunter | 9896246 | 2009-08-18 12:45:10 -0500 | [diff] [blame] | 398 | } |
Woodruff, Richard | 0014744 | 2008-12-01 14:18:11 -0800 | [diff] [blame] | 399 | |
Thomas Gleixner | 2718501 | 2009-11-12 22:12:06 +0100 | [diff] [blame] | 400 | if (time_delta < KTIME_MAX) |
| 401 | expires = ktime_add_ns(last_update, time_delta); |
| 402 | else |
| 403 | expires.tv64 = KTIME_MAX; |
Woodruff, Richard | 0014744 | 2008-12-01 14:18:11 -0800 | [diff] [blame] | 404 | |
Woodruff, Richard | 0014744 | 2008-12-01 14:18:11 -0800 | [diff] [blame] | 405 | /* Skip reprogram of event if its not changed */ |
| 406 | if (ts->tick_stopped && ktime_equal(expires, dev->next_event)) |
| 407 | goto out; |
| 408 | |
Frederic Weisbecker | 84bf1bc | 2011-08-01 01:25:38 +0200 | [diff] [blame] | 409 | ret = expires; |
| 410 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 411 | /* |
| 412 | * nohz_stop_sched_tick can be called several times before |
| 413 | * the nohz_restart_sched_tick is called. This happens when |
| 414 | * interrupts arrive which do not cause a reschedule. In the |
| 415 | * first call we save the current tick time, so we can restart |
| 416 | * the scheduler tick in nohz_restart_sched_tick. |
| 417 | */ |
| 418 | if (!ts->tick_stopped) { |
Alex Shi | c1cc017 | 2012-09-10 15:10:58 +0800 | [diff] [blame] | 419 | nohz_balance_enter_idle(cpu); |
Peter Zijlstra | 5167e8d | 2012-06-22 15:52:09 +0200 | [diff] [blame] | 420 | calc_load_enter_idle(); |
Siddha, Suresh B | 46cb4b7 | 2007-05-08 00:32:51 -0700 | [diff] [blame] | 421 | |
Frederic Weisbecker | f5d411c | 2011-07-31 17:44:12 +0200 | [diff] [blame] | 422 | ts->last_tick = hrtimer_get_expires(&ts->sched_timer); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 423 | ts->tick_stopped = 1; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 424 | } |
Thomas Gleixner | d3ed782 | 2007-05-08 00:30:03 -0700 | [diff] [blame] | 425 | |
Thomas Gleixner | eaad084 | 2007-05-29 23:47:39 +0200 | [diff] [blame] | 426 | /* |
Jon Hunter | 9896246 | 2009-08-18 12:45:10 -0500 | [diff] [blame] | 427 | * If the expiration time == KTIME_MAX, then |
| 428 | * in this case we simply stop the tick timer. |
Thomas Gleixner | eaad084 | 2007-05-29 23:47:39 +0200 | [diff] [blame] | 429 | */ |
Jon Hunter | 9896246 | 2009-08-18 12:45:10 -0500 | [diff] [blame] | 430 | if (unlikely(expires.tv64 == KTIME_MAX)) { |
Thomas Gleixner | eaad084 | 2007-05-29 23:47:39 +0200 | [diff] [blame] | 431 | if (ts->nohz_mode == NOHZ_MODE_HIGHRES) |
| 432 | hrtimer_cancel(&ts->sched_timer); |
| 433 | goto out; |
| 434 | } |
| 435 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 436 | if (ts->nohz_mode == NOHZ_MODE_HIGHRES) { |
| 437 | hrtimer_start(&ts->sched_timer, expires, |
Arun R Bharadwaj | 5c33386 | 2009-04-16 12:14:37 +0530 | [diff] [blame] | 438 | HRTIMER_MODE_ABS_PINNED); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 439 | /* Check, if the timer was already in the past */ |
| 440 | if (hrtimer_active(&ts->sched_timer)) |
| 441 | goto out; |
Pavel Machek | 4c9dc64 | 2008-01-30 13:30:00 +0100 | [diff] [blame] | 442 | } else if (!tick_program_event(expires, 0)) |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 443 | goto out; |
| 444 | /* |
| 445 | * We are past the event already. So we crossed a |
| 446 | * jiffie boundary. Update jiffies and raise the |
| 447 | * softirq. |
| 448 | */ |
| 449 | tick_do_update_jiffies64(ktime_get()); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 450 | } |
| 451 | raise_softirq_irqoff(TIMER_SOFTIRQ); |
| 452 | out: |
| 453 | ts->next_jiffies = next_jiffies; |
| 454 | ts->last_jiffies = last_jiffies; |
Len Brown | 4f86d3a | 2007-10-03 18:58:00 -0400 | [diff] [blame] | 455 | ts->sleep_length = ktime_sub(dev->next_event, now); |
Frederic Weisbecker | 84bf1bc | 2011-08-01 01:25:38 +0200 | [diff] [blame] | 456 | |
| 457 | return ret; |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 458 | } |
| 459 | |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 460 | static bool can_stop_idle_tick(int cpu, struct tick_sched *ts) |
| 461 | { |
| 462 | /* |
| 463 | * If this cpu is offline and it is the one which updates |
| 464 | * jiffies, then give up the assignment and let it be taken by |
| 465 | * the cpu which runs the tick timer next. If we don't drop |
| 466 | * this here the jiffies might be stale and do_timer() never |
| 467 | * invoked. |
| 468 | */ |
| 469 | if (unlikely(!cpu_online(cpu))) { |
| 470 | if (cpu == tick_do_timer_cpu) |
| 471 | tick_do_timer_cpu = TICK_DO_TIMER_NONE; |
Thomas Gleixner | f7ea0fd | 2013-05-13 21:40:27 +0200 | [diff] [blame^] | 472 | return false; |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 473 | } |
| 474 | |
| 475 | if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE)) |
| 476 | return false; |
| 477 | |
| 478 | if (need_resched()) |
| 479 | return false; |
| 480 | |
| 481 | if (unlikely(local_softirq_pending() && cpu_online(cpu))) { |
| 482 | static int ratelimit; |
| 483 | |
Paul E. McKenney | 803b0eb | 2012-08-23 08:34:07 -0700 | [diff] [blame] | 484 | if (ratelimit < 10 && |
| 485 | (local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK)) { |
Rado Vrbovsky | cfea7d7 | 2013-02-08 12:37:30 -0500 | [diff] [blame] | 486 | pr_warn("NOHZ: local_softirq_pending %02x\n", |
| 487 | (unsigned int) local_softirq_pending()); |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 488 | ratelimit++; |
| 489 | } |
| 490 | return false; |
| 491 | } |
| 492 | |
| 493 | return true; |
| 494 | } |
| 495 | |
Frederic Weisbecker | 19f5f73 | 2011-07-27 17:29:28 +0200 | [diff] [blame] | 496 | static void __tick_nohz_idle_enter(struct tick_sched *ts) |
| 497 | { |
Frederic Weisbecker | 84bf1bc | 2011-08-01 01:25:38 +0200 | [diff] [blame] | 498 | ktime_t now, expires; |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 499 | int cpu = smp_processor_id(); |
Frederic Weisbecker | 19f5f73 | 2011-07-27 17:29:28 +0200 | [diff] [blame] | 500 | |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 501 | now = tick_nohz_start_idle(cpu, ts); |
Frederic Weisbecker | 2ac0d98 | 2011-07-28 04:00:47 +0200 | [diff] [blame] | 502 | |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 503 | if (can_stop_idle_tick(cpu, ts)) { |
| 504 | int was_stopped = ts->tick_stopped; |
| 505 | |
| 506 | ts->idle_calls++; |
Frederic Weisbecker | 84bf1bc | 2011-08-01 01:25:38 +0200 | [diff] [blame] | 507 | |
| 508 | expires = tick_nohz_stop_sched_tick(ts, now, cpu); |
| 509 | if (expires.tv64 > 0LL) { |
| 510 | ts->idle_sleeps++; |
| 511 | ts->idle_expires = expires; |
| 512 | } |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 513 | |
| 514 | if (!was_stopped && ts->tick_stopped) |
| 515 | ts->idle_jiffies = ts->last_jiffies; |
| 516 | } |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 517 | } |
| 518 | |
| 519 | /** |
| 520 | * tick_nohz_idle_enter - stop the idle tick from the idle task |
| 521 | * |
| 522 | * When the next event is more than a tick into the future, stop the idle tick |
| 523 | * Called when we start the idle loop. |
Frederic Weisbecker | 2bbb681 | 2011-10-08 16:01:00 +0200 | [diff] [blame] | 524 | * |
Frederic Weisbecker | 1268fbc | 2011-11-17 18:48:14 +0100 | [diff] [blame] | 525 | * The arch is responsible of calling: |
Frederic Weisbecker | 2bbb681 | 2011-10-08 16:01:00 +0200 | [diff] [blame] | 526 | * |
| 527 | * - rcu_idle_enter() after its last use of RCU before the CPU is put |
| 528 | * to sleep. |
| 529 | * - rcu_idle_exit() before the first use of RCU after the CPU is woken up. |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 530 | */ |
Frederic Weisbecker | 1268fbc | 2011-11-17 18:48:14 +0100 | [diff] [blame] | 531 | void tick_nohz_idle_enter(void) |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 532 | { |
| 533 | struct tick_sched *ts; |
| 534 | |
Frederic Weisbecker | 1268fbc | 2011-11-17 18:48:14 +0100 | [diff] [blame] | 535 | WARN_ON_ONCE(irqs_disabled()); |
| 536 | |
Linus Torvalds | 0db49b7 | 2012-01-06 08:33:28 -0800 | [diff] [blame] | 537 | /* |
| 538 | * Update the idle state in the scheduler domain hierarchy |
| 539 | * when tick_nohz_stop_sched_tick() is called from the idle loop. |
| 540 | * State will be updated to busy during the first busy tick after |
| 541 | * exiting idle. |
| 542 | */ |
| 543 | set_cpu_sd_state_idle(); |
| 544 | |
Frederic Weisbecker | 1268fbc | 2011-11-17 18:48:14 +0100 | [diff] [blame] | 545 | local_irq_disable(); |
| 546 | |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 547 | ts = &__get_cpu_var(tick_cpu_sched); |
| 548 | /* |
| 549 | * set ts->inidle unconditionally. even if the system did not |
| 550 | * switch to nohz mode the cpu frequency governers rely on the |
| 551 | * update of the idle time accounting in tick_nohz_start_idle(). |
| 552 | */ |
| 553 | ts->inidle = 1; |
Frederic Weisbecker | 19f5f73 | 2011-07-27 17:29:28 +0200 | [diff] [blame] | 554 | __tick_nohz_idle_enter(ts); |
Frederic Weisbecker | 1268fbc | 2011-11-17 18:48:14 +0100 | [diff] [blame] | 555 | |
| 556 | local_irq_enable(); |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 557 | } |
Jacob Pan | 4dbd277 | 2013-01-04 11:12:43 +0000 | [diff] [blame] | 558 | EXPORT_SYMBOL_GPL(tick_nohz_idle_enter); |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 559 | |
| 560 | /** |
| 561 | * tick_nohz_irq_exit - update next tick event from interrupt exit |
| 562 | * |
| 563 | * When an interrupt fires while we are idle and it doesn't cause |
| 564 | * a reschedule, it may still add, modify or delete a timer, enqueue |
| 565 | * an RCU callback, etc... |
| 566 | * So we need to re-calculate and reprogram the next tick event. |
| 567 | */ |
| 568 | void tick_nohz_irq_exit(void) |
| 569 | { |
| 570 | struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched); |
| 571 | |
| 572 | if (!ts->inidle) |
| 573 | return; |
| 574 | |
Youquan Song | 69a37be | 2012-10-26 12:26:41 +0200 | [diff] [blame] | 575 | /* Cancel the timer because CPU already waken up from the C-states*/ |
| 576 | menu_hrtimer_cancel(); |
Frederic Weisbecker | 19f5f73 | 2011-07-27 17:29:28 +0200 | [diff] [blame] | 577 | __tick_nohz_idle_enter(ts); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 578 | } |
| 579 | |
| 580 | /** |
Len Brown | 4f86d3a | 2007-10-03 18:58:00 -0400 | [diff] [blame] | 581 | * tick_nohz_get_sleep_length - return the length of the current sleep |
| 582 | * |
| 583 | * Called from power state control code with interrupts disabled |
| 584 | */ |
| 585 | ktime_t tick_nohz_get_sleep_length(void) |
| 586 | { |
| 587 | struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched); |
| 588 | |
| 589 | return ts->sleep_length; |
| 590 | } |
| 591 | |
Thomas Gleixner | c34bec5 | 2008-10-17 10:04:34 +0200 | [diff] [blame] | 592 | static void tick_nohz_restart(struct tick_sched *ts, ktime_t now) |
| 593 | { |
| 594 | hrtimer_cancel(&ts->sched_timer); |
Frederic Weisbecker | f5d411c | 2011-07-31 17:44:12 +0200 | [diff] [blame] | 595 | hrtimer_set_expires(&ts->sched_timer, ts->last_tick); |
Thomas Gleixner | c34bec5 | 2008-10-17 10:04:34 +0200 | [diff] [blame] | 596 | |
| 597 | while (1) { |
| 598 | /* Forward the time to expire in the future */ |
| 599 | hrtimer_forward(&ts->sched_timer, now, tick_period); |
| 600 | |
| 601 | if (ts->nohz_mode == NOHZ_MODE_HIGHRES) { |
Thomas Gleixner | 268a3dc | 2008-10-22 09:48:06 +0200 | [diff] [blame] | 602 | hrtimer_start_expires(&ts->sched_timer, |
Arun R Bharadwaj | 5c33386 | 2009-04-16 12:14:37 +0530 | [diff] [blame] | 603 | HRTIMER_MODE_ABS_PINNED); |
Thomas Gleixner | c34bec5 | 2008-10-17 10:04:34 +0200 | [diff] [blame] | 604 | /* Check, if the timer was already in the past */ |
| 605 | if (hrtimer_active(&ts->sched_timer)) |
| 606 | break; |
| 607 | } else { |
Thomas Gleixner | 268a3dc | 2008-10-22 09:48:06 +0200 | [diff] [blame] | 608 | if (!tick_program_event( |
| 609 | hrtimer_get_expires(&ts->sched_timer), 0)) |
Thomas Gleixner | c34bec5 | 2008-10-17 10:04:34 +0200 | [diff] [blame] | 610 | break; |
| 611 | } |
Neal Cardwell | 6f10392 | 2012-03-27 15:09:37 -0400 | [diff] [blame] | 612 | /* Reread time and update jiffies */ |
Thomas Gleixner | c34bec5 | 2008-10-17 10:04:34 +0200 | [diff] [blame] | 613 | now = ktime_get(); |
Neal Cardwell | 6f10392 | 2012-03-27 15:09:37 -0400 | [diff] [blame] | 614 | tick_do_update_jiffies64(now); |
Thomas Gleixner | c34bec5 | 2008-10-17 10:04:34 +0200 | [diff] [blame] | 615 | } |
| 616 | } |
| 617 | |
Frederic Weisbecker | 19f5f73 | 2011-07-27 17:29:28 +0200 | [diff] [blame] | 618 | static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now) |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 619 | { |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 620 | /* Update jiffies first */ |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 621 | tick_do_update_jiffies64(now); |
Peter Zijlstra | 5aaa0b7 | 2012-05-17 17:15:29 +0200 | [diff] [blame] | 622 | update_cpu_load_nohz(); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 623 | |
Charles Wang | 749c881 | 2012-08-20 16:02:33 +0800 | [diff] [blame] | 624 | calc_load_exit_idle(); |
Frederic Weisbecker | 2ac0d98 | 2011-07-28 04:00:47 +0200 | [diff] [blame] | 625 | touch_softlockup_watchdog(); |
| 626 | /* |
| 627 | * Cancel the scheduled timer and restore the tick |
| 628 | */ |
| 629 | ts->tick_stopped = 0; |
| 630 | ts->idle_exittime = now; |
| 631 | |
| 632 | tick_nohz_restart(ts, now); |
| 633 | } |
| 634 | |
| 635 | static void tick_nohz_account_idle_ticks(struct tick_sched *ts) |
| 636 | { |
Frederic Weisbecker | 3f4724e | 2012-07-16 18:00:34 +0200 | [diff] [blame] | 637 | #ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE |
Frederic Weisbecker | 2ac0d98 | 2011-07-28 04:00:47 +0200 | [diff] [blame] | 638 | unsigned long ticks; |
Frederic Weisbecker | 3f4724e | 2012-07-16 18:00:34 +0200 | [diff] [blame] | 639 | |
| 640 | if (vtime_accounting_enabled()) |
| 641 | return; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 642 | /* |
| 643 | * We stopped the tick in idle. Update process times would miss the |
| 644 | * time we slept as update_process_times does only a 1 tick |
| 645 | * accounting. Enforce that this is accounted to idle ! |
| 646 | */ |
| 647 | ticks = jiffies - ts->idle_jiffies; |
| 648 | /* |
| 649 | * We might be one off. Do not randomly account a huge number of ticks! |
| 650 | */ |
Martin Schwidefsky | 79741dd | 2008-12-31 15:11:38 +0100 | [diff] [blame] | 651 | if (ticks && ticks < LONG_MAX) |
| 652 | account_idle_ticks(ticks); |
| 653 | #endif |
Frederic Weisbecker | 19f5f73 | 2011-07-27 17:29:28 +0200 | [diff] [blame] | 654 | } |
| 655 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 656 | /** |
| 657 | * tick_nohz_idle_exit - restart the idle tick from the idle task |
| 658 | * |
| 659 | * Restart the idle tick when the CPU is woken up from idle |
| 660 | * This also exit the RCU extended quiescent state. The CPU |
| 661 | * can use RCU again after this function is called. |
| 662 | */ |
| 663 | void tick_nohz_idle_exit(void) |
| 664 | { |
| 665 | int cpu = smp_processor_id(); |
| 666 | struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 667 | ktime_t now; |
| 668 | |
| 669 | local_irq_disable(); |
| 670 | |
| 671 | WARN_ON_ONCE(!ts->inidle); |
| 672 | |
| 673 | ts->inidle = 0; |
| 674 | |
Youquan Song | 69a37be | 2012-10-26 12:26:41 +0200 | [diff] [blame] | 675 | /* Cancel the timer because CPU already waken up from the C-states*/ |
| 676 | menu_hrtimer_cancel(); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 677 | if (ts->idle_active || ts->tick_stopped) |
| 678 | now = ktime_get(); |
| 679 | |
| 680 | if (ts->idle_active) |
| 681 | tick_nohz_stop_idle(cpu, now); |
| 682 | |
Frederic Weisbecker | 2ac0d98 | 2011-07-28 04:00:47 +0200 | [diff] [blame] | 683 | if (ts->tick_stopped) { |
Frederic Weisbecker | 19f5f73 | 2011-07-27 17:29:28 +0200 | [diff] [blame] | 684 | tick_nohz_restart_sched_tick(ts, now); |
Frederic Weisbecker | 2ac0d98 | 2011-07-28 04:00:47 +0200 | [diff] [blame] | 685 | tick_nohz_account_idle_ticks(ts); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 686 | } |
| 687 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 688 | local_irq_enable(); |
| 689 | } |
Jacob Pan | 4dbd277 | 2013-01-04 11:12:43 +0000 | [diff] [blame] | 690 | EXPORT_SYMBOL_GPL(tick_nohz_idle_exit); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 691 | |
| 692 | static int tick_nohz_reprogram(struct tick_sched *ts, ktime_t now) |
| 693 | { |
| 694 | hrtimer_forward(&ts->sched_timer, now, tick_period); |
Arjan van de Ven | cc584b2 | 2008-09-01 15:02:30 -0700 | [diff] [blame] | 695 | return tick_program_event(hrtimer_get_expires(&ts->sched_timer), 0); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 696 | } |
| 697 | |
| 698 | /* |
| 699 | * The nohz low res interrupt handler |
| 700 | */ |
| 701 | static void tick_nohz_handler(struct clock_event_device *dev) |
| 702 | { |
| 703 | struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched); |
| 704 | struct pt_regs *regs = get_irq_regs(); |
| 705 | ktime_t now = ktime_get(); |
| 706 | |
| 707 | dev->next_event.tv64 = KTIME_MAX; |
| 708 | |
Frederic Weisbecker | 5bb9622 | 2012-10-15 02:03:27 +0200 | [diff] [blame] | 709 | tick_sched_do_timer(now); |
Frederic Weisbecker | 9e8f559 | 2012-10-15 02:43:03 +0200 | [diff] [blame] | 710 | tick_sched_handle(ts, regs); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 711 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 712 | while (tick_nohz_reprogram(ts, now)) { |
| 713 | now = ktime_get(); |
| 714 | tick_do_update_jiffies64(now); |
| 715 | } |
| 716 | } |
| 717 | |
| 718 | /** |
| 719 | * tick_nohz_switch_to_nohz - switch to nohz mode |
| 720 | */ |
| 721 | static void tick_nohz_switch_to_nohz(void) |
| 722 | { |
| 723 | struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched); |
| 724 | ktime_t next; |
| 725 | |
| 726 | if (!tick_nohz_enabled) |
| 727 | return; |
| 728 | |
| 729 | local_irq_disable(); |
| 730 | if (tick_switch_to_oneshot(tick_nohz_handler)) { |
| 731 | local_irq_enable(); |
| 732 | return; |
| 733 | } |
| 734 | |
| 735 | ts->nohz_mode = NOHZ_MODE_LOWRES; |
| 736 | |
| 737 | /* |
| 738 | * Recycle the hrtimer in ts, so we can share the |
| 739 | * hrtimer_forward with the highres code. |
| 740 | */ |
| 741 | hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); |
| 742 | /* Get the next period */ |
| 743 | next = tick_init_jiffy_update(); |
| 744 | |
| 745 | for (;;) { |
Arjan van de Ven | cc584b2 | 2008-09-01 15:02:30 -0700 | [diff] [blame] | 746 | hrtimer_set_expires(&ts->sched_timer, next); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 747 | if (!tick_program_event(next, 0)) |
| 748 | break; |
| 749 | next = ktime_add(next, tick_period); |
| 750 | } |
| 751 | local_irq_enable(); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 752 | } |
| 753 | |
Thomas Gleixner | fb02fbc | 2008-10-17 10:01:23 +0200 | [diff] [blame] | 754 | /* |
| 755 | * When NOHZ is enabled and the tick is stopped, we need to kick the |
| 756 | * tick timer from irq_enter() so that the jiffies update is kept |
| 757 | * alive during long running softirqs. That's ugly as hell, but |
| 758 | * correctness is key even if we need to fix the offending softirq in |
| 759 | * the first place. |
| 760 | * |
| 761 | * Note, this is different to tick_nohz_restart. We just kick the |
| 762 | * timer and do not touch the other magic bits which need to be done |
| 763 | * when idle is left. |
| 764 | */ |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 765 | static void tick_nohz_kick_tick(int cpu, ktime_t now) |
Thomas Gleixner | fb02fbc | 2008-10-17 10:01:23 +0200 | [diff] [blame] | 766 | { |
Thomas Gleixner | ae99286 | 2008-11-10 13:20:23 +0100 | [diff] [blame] | 767 | #if 0 |
| 768 | /* Switch back to 2.6.27 behaviour */ |
| 769 | |
Thomas Gleixner | fb02fbc | 2008-10-17 10:01:23 +0200 | [diff] [blame] | 770 | struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 771 | ktime_t delta; |
Thomas Gleixner | fb02fbc | 2008-10-17 10:01:23 +0200 | [diff] [blame] | 772 | |
Thomas Gleixner | c4bd822 | 2008-10-21 20:17:35 +0200 | [diff] [blame] | 773 | /* |
| 774 | * Do not touch the tick device, when the next expiry is either |
| 775 | * already reached or less/equal than the tick period. |
| 776 | */ |
Thomas Gleixner | 268a3dc | 2008-10-22 09:48:06 +0200 | [diff] [blame] | 777 | delta = ktime_sub(hrtimer_get_expires(&ts->sched_timer), now); |
Thomas Gleixner | c4bd822 | 2008-10-21 20:17:35 +0200 | [diff] [blame] | 778 | if (delta.tv64 <= tick_period.tv64) |
| 779 | return; |
| 780 | |
| 781 | tick_nohz_restart(ts, now); |
Thomas Gleixner | ae99286 | 2008-11-10 13:20:23 +0100 | [diff] [blame] | 782 | #endif |
Thomas Gleixner | fb02fbc | 2008-10-17 10:01:23 +0200 | [diff] [blame] | 783 | } |
| 784 | |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 785 | static inline void tick_check_nohz(int cpu) |
| 786 | { |
| 787 | struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); |
| 788 | ktime_t now; |
| 789 | |
| 790 | if (!ts->idle_active && !ts->tick_stopped) |
| 791 | return; |
| 792 | now = ktime_get(); |
| 793 | if (ts->idle_active) |
| 794 | tick_nohz_stop_idle(cpu, now); |
| 795 | if (ts->tick_stopped) { |
| 796 | tick_nohz_update_jiffies(now); |
| 797 | tick_nohz_kick_tick(cpu, now); |
| 798 | } |
| 799 | } |
| 800 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 801 | #else |
| 802 | |
| 803 | static inline void tick_nohz_switch_to_nohz(void) { } |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 804 | static inline void tick_check_nohz(int cpu) { } |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 805 | |
| 806 | #endif /* NO_HZ */ |
| 807 | |
| 808 | /* |
Thomas Gleixner | 719254f | 2008-10-17 09:59:47 +0200 | [diff] [blame] | 809 | * Called from irq_enter to notify about the possible interruption of idle() |
| 810 | */ |
| 811 | void tick_check_idle(int cpu) |
| 812 | { |
Thomas Gleixner | fb02fbc | 2008-10-17 10:01:23 +0200 | [diff] [blame] | 813 | tick_check_oneshot_broadcast(cpu); |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 814 | tick_check_nohz(cpu); |
Thomas Gleixner | 719254f | 2008-10-17 09:59:47 +0200 | [diff] [blame] | 815 | } |
| 816 | |
| 817 | /* |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 818 | * High resolution timer specific code |
| 819 | */ |
| 820 | #ifdef CONFIG_HIGH_RES_TIMERS |
| 821 | /* |
Pavel Machek | 4c9dc64 | 2008-01-30 13:30:00 +0100 | [diff] [blame] | 822 | * We rearm the timer until we get disabled by the idle code. |
Chuansheng Liu | 351f181 | 2012-10-25 01:07:35 +0800 | [diff] [blame] | 823 | * Called with interrupts disabled. |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 824 | */ |
| 825 | static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer) |
| 826 | { |
| 827 | struct tick_sched *ts = |
| 828 | container_of(timer, struct tick_sched, sched_timer); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 829 | struct pt_regs *regs = get_irq_regs(); |
| 830 | ktime_t now = ktime_get(); |
Thomas Gleixner | d3ed782 | 2007-05-08 00:30:03 -0700 | [diff] [blame] | 831 | |
Frederic Weisbecker | 5bb9622 | 2012-10-15 02:03:27 +0200 | [diff] [blame] | 832 | tick_sched_do_timer(now); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 833 | |
| 834 | /* |
| 835 | * Do not call, when we are not in irq context and have |
| 836 | * no valid regs pointer |
| 837 | */ |
Frederic Weisbecker | 9e8f559 | 2012-10-15 02:43:03 +0200 | [diff] [blame] | 838 | if (regs) |
| 839 | tick_sched_handle(ts, regs); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 840 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 841 | hrtimer_forward(timer, now, tick_period); |
| 842 | |
| 843 | return HRTIMER_RESTART; |
| 844 | } |
| 845 | |
Mike Galbraith | 5307c95 | 2012-05-08 12:20:58 +0200 | [diff] [blame] | 846 | static int sched_skew_tick; |
| 847 | |
Thomas Gleixner | 62cf20b | 2012-05-25 14:08:57 +0200 | [diff] [blame] | 848 | static int __init skew_tick(char *str) |
| 849 | { |
| 850 | get_option(&str, &sched_skew_tick); |
| 851 | |
| 852 | return 0; |
| 853 | } |
| 854 | early_param("skew_tick", skew_tick); |
| 855 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 856 | /** |
| 857 | * tick_setup_sched_timer - setup the tick emulation timer |
| 858 | */ |
| 859 | void tick_setup_sched_timer(void) |
| 860 | { |
| 861 | struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched); |
| 862 | ktime_t now = ktime_get(); |
| 863 | |
| 864 | /* |
| 865 | * Emulate tick processing via per-CPU hrtimers: |
| 866 | */ |
| 867 | hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); |
| 868 | ts->sched_timer.function = tick_sched_timer; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 869 | |
john stultz | 3704540 | 2007-07-21 04:37:35 -0700 | [diff] [blame] | 870 | /* Get the next period (per cpu) */ |
Arjan van de Ven | cc584b2 | 2008-09-01 15:02:30 -0700 | [diff] [blame] | 871 | hrtimer_set_expires(&ts->sched_timer, tick_init_jiffy_update()); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 872 | |
Thomas Gleixner | 9c3f9e2 | 2012-11-21 20:31:52 +0100 | [diff] [blame] | 873 | /* Offset the tick to avert jiffies_lock contention. */ |
Mike Galbraith | 5307c95 | 2012-05-08 12:20:58 +0200 | [diff] [blame] | 874 | if (sched_skew_tick) { |
| 875 | u64 offset = ktime_to_ns(tick_period) >> 1; |
| 876 | do_div(offset, num_possible_cpus()); |
| 877 | offset *= smp_processor_id(); |
| 878 | hrtimer_add_expires_ns(&ts->sched_timer, offset); |
| 879 | } |
| 880 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 881 | for (;;) { |
| 882 | hrtimer_forward(&ts->sched_timer, now, tick_period); |
Arun R Bharadwaj | 5c33386 | 2009-04-16 12:14:37 +0530 | [diff] [blame] | 883 | hrtimer_start_expires(&ts->sched_timer, |
| 884 | HRTIMER_MODE_ABS_PINNED); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 885 | /* Check, if the timer was already in the past */ |
| 886 | if (hrtimer_active(&ts->sched_timer)) |
| 887 | break; |
| 888 | now = ktime_get(); |
| 889 | } |
| 890 | |
| 891 | #ifdef CONFIG_NO_HZ |
Heiko Carstens | 29c158e | 2011-08-23 13:20:46 +0200 | [diff] [blame] | 892 | if (tick_nohz_enabled) |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 893 | ts->nohz_mode = NOHZ_MODE_HIGHRES; |
| 894 | #endif |
| 895 | } |
Miao Xie | 3c4fbe5 | 2008-08-20 16:37:38 -0700 | [diff] [blame] | 896 | #endif /* HIGH_RES_TIMERS */ |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 897 | |
Miao Xie | 3c4fbe5 | 2008-08-20 16:37:38 -0700 | [diff] [blame] | 898 | #if defined CONFIG_NO_HZ || defined CONFIG_HIGH_RES_TIMERS |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 899 | void tick_cancel_sched_timer(int cpu) |
| 900 | { |
| 901 | struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); |
| 902 | |
Miao Xie | 3c4fbe5 | 2008-08-20 16:37:38 -0700 | [diff] [blame] | 903 | # ifdef CONFIG_HIGH_RES_TIMERS |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 904 | if (ts->sched_timer.base) |
| 905 | hrtimer_cancel(&ts->sched_timer); |
Miao Xie | 3c4fbe5 | 2008-08-20 16:37:38 -0700 | [diff] [blame] | 906 | # endif |
Karsten Wiese | a790176 | 2008-03-04 14:59:55 -0800 | [diff] [blame] | 907 | |
Thomas Gleixner | 4b0c0f2 | 2013-05-03 15:02:50 +0200 | [diff] [blame] | 908 | memset(ts, 0, sizeof(*ts)); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 909 | } |
Miao Xie | 3c4fbe5 | 2008-08-20 16:37:38 -0700 | [diff] [blame] | 910 | #endif |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 911 | |
| 912 | /** |
| 913 | * Async notification about clocksource changes |
| 914 | */ |
| 915 | void tick_clock_notify(void) |
| 916 | { |
| 917 | int cpu; |
| 918 | |
| 919 | for_each_possible_cpu(cpu) |
| 920 | set_bit(0, &per_cpu(tick_cpu_sched, cpu).check_clocks); |
| 921 | } |
| 922 | |
| 923 | /* |
| 924 | * Async notification about clock event changes |
| 925 | */ |
| 926 | void tick_oneshot_notify(void) |
| 927 | { |
| 928 | struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched); |
| 929 | |
| 930 | set_bit(0, &ts->check_clocks); |
| 931 | } |
| 932 | |
| 933 | /** |
| 934 | * Check, if a change happened, which makes oneshot possible. |
| 935 | * |
| 936 | * Called cyclic from the hrtimer softirq (driven by the timer |
| 937 | * softirq) allow_nohz signals, that we can switch into low-res nohz |
| 938 | * mode, because high resolution timers are disabled (either compile |
| 939 | * or runtime). |
| 940 | */ |
| 941 | int tick_check_oneshot_change(int allow_nohz) |
| 942 | { |
| 943 | struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched); |
| 944 | |
| 945 | if (!test_and_clear_bit(0, &ts->check_clocks)) |
| 946 | return 0; |
| 947 | |
| 948 | if (ts->nohz_mode != NOHZ_MODE_INACTIVE) |
| 949 | return 0; |
| 950 | |
Li Zefan | cf4fc6c | 2008-02-08 04:19:24 -0800 | [diff] [blame] | 951 | if (!timekeeping_valid_for_hres() || !tick_is_oneshot_available()) |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 952 | return 0; |
| 953 | |
| 954 | if (!allow_nohz) |
| 955 | return 1; |
| 956 | |
| 957 | tick_nohz_switch_to_nohz(); |
| 958 | return 0; |
| 959 | } |