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> |
Frederic Weisbecker | 9014c45 | 2013-04-20 15:43:57 +0200 | [diff] [blame] | 24 | #include <linux/posix-timers.h> |
| 25 | #include <linux/perf_event.h> |
Frederic Weisbecker | 2e70933 | 2013-07-10 00:55:25 +0200 | [diff] [blame] | 26 | #include <linux/context_tracking.h> |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 27 | |
David S. Miller | 9e203bc | 2007-02-24 22:10:13 -0800 | [diff] [blame] | 28 | #include <asm/irq_regs.h> |
| 29 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 30 | #include "tick-internal.h" |
| 31 | |
Frederic Weisbecker | cb41a29 | 2013-04-20 17:35:50 +0200 | [diff] [blame] | 32 | #include <trace/events/timer.h> |
| 33 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 34 | /* |
| 35 | * Per cpu nohz control structure |
| 36 | */ |
Frederic Weisbecker | 33a5f62 | 2012-10-11 17:52:56 +0200 | [diff] [blame] | 37 | DEFINE_PER_CPU(struct tick_sched, tick_cpu_sched); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 38 | |
| 39 | /* |
John Stultz | d6ad418 | 2012-02-28 16:50:11 -0800 | [diff] [blame] | 40 | * The time, when the last jiffy update happened. Protected by jiffies_lock. |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 41 | */ |
| 42 | static ktime_t last_jiffies_update; |
| 43 | |
Ingo Molnar | 289f480 | 2007-02-16 01:28:15 -0800 | [diff] [blame] | 44 | struct tick_sched *tick_get_tick_sched(int cpu) |
| 45 | { |
| 46 | return &per_cpu(tick_cpu_sched, cpu); |
| 47 | } |
| 48 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 49 | /* |
| 50 | * Must be called with interrupts disabled ! |
| 51 | */ |
| 52 | static void tick_do_update_jiffies64(ktime_t now) |
| 53 | { |
| 54 | unsigned long ticks = 0; |
| 55 | ktime_t delta; |
| 56 | |
Ingo Molnar | 7a14ce1 | 2008-05-12 15:43:53 +0200 | [diff] [blame] | 57 | /* |
John Stultz | d6ad418 | 2012-02-28 16:50:11 -0800 | [diff] [blame] | 58 | * Do a quick check without holding jiffies_lock: |
Ingo Molnar | 7a14ce1 | 2008-05-12 15:43:53 +0200 | [diff] [blame] | 59 | */ |
| 60 | delta = ktime_sub(now, last_jiffies_update); |
| 61 | if (delta.tv64 < tick_period.tv64) |
| 62 | return; |
| 63 | |
John Stultz | d6ad418 | 2012-02-28 16:50:11 -0800 | [diff] [blame] | 64 | /* Reevalute with jiffies_lock held */ |
| 65 | write_seqlock(&jiffies_lock); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 66 | |
| 67 | delta = ktime_sub(now, last_jiffies_update); |
| 68 | if (delta.tv64 >= tick_period.tv64) { |
| 69 | |
| 70 | delta = ktime_sub(delta, tick_period); |
| 71 | last_jiffies_update = ktime_add(last_jiffies_update, |
| 72 | tick_period); |
| 73 | |
| 74 | /* Slow path for long timeouts */ |
| 75 | if (unlikely(delta.tv64 >= tick_period.tv64)) { |
| 76 | s64 incr = ktime_to_ns(tick_period); |
| 77 | |
| 78 | ticks = ktime_divns(delta, incr); |
| 79 | |
| 80 | last_jiffies_update = ktime_add_ns(last_jiffies_update, |
| 81 | incr * ticks); |
| 82 | } |
| 83 | do_timer(++ticks); |
Thomas Gleixner | 49d670f | 2008-09-22 18:56:01 +0200 | [diff] [blame] | 84 | |
| 85 | /* Keep the tick_next_period variable up to date */ |
| 86 | tick_next_period = ktime_add(last_jiffies_update, tick_period); |
Viresh Kumar | 03e6bdc | 2014-04-15 10:54:40 +0530 | [diff] [blame] | 87 | } else { |
| 88 | write_sequnlock(&jiffies_lock); |
| 89 | return; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 90 | } |
John Stultz | d6ad418 | 2012-02-28 16:50:11 -0800 | [diff] [blame] | 91 | write_sequnlock(&jiffies_lock); |
John Stultz | 47a1b796 | 2013-12-12 13:10:55 -0800 | [diff] [blame] | 92 | update_wall_time(); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 93 | } |
| 94 | |
| 95 | /* |
| 96 | * Initialize and return retrieve the jiffies update. |
| 97 | */ |
| 98 | static ktime_t tick_init_jiffy_update(void) |
| 99 | { |
| 100 | ktime_t period; |
| 101 | |
John Stultz | d6ad418 | 2012-02-28 16:50:11 -0800 | [diff] [blame] | 102 | write_seqlock(&jiffies_lock); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 103 | /* Did we start the jiffies update yet ? */ |
| 104 | if (last_jiffies_update.tv64 == 0) |
| 105 | last_jiffies_update = tick_next_period; |
| 106 | period = last_jiffies_update; |
John Stultz | d6ad418 | 2012-02-28 16:50:11 -0800 | [diff] [blame] | 107 | write_sequnlock(&jiffies_lock); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 108 | return period; |
| 109 | } |
| 110 | |
Frederic Weisbecker | 5bb9622 | 2012-10-15 02:03:27 +0200 | [diff] [blame] | 111 | |
| 112 | static void tick_sched_do_timer(ktime_t now) |
| 113 | { |
| 114 | int cpu = smp_processor_id(); |
| 115 | |
Frederic Weisbecker | 3451d02 | 2011-08-10 23:21:01 +0200 | [diff] [blame] | 116 | #ifdef CONFIG_NO_HZ_COMMON |
Frederic Weisbecker | 5bb9622 | 2012-10-15 02:03:27 +0200 | [diff] [blame] | 117 | /* |
| 118 | * Check if the do_timer duty was dropped. We don't care about |
| 119 | * concurrency: This happens only when the cpu in charge went |
| 120 | * into a long sleep. If two cpus happen to assign themself to |
| 121 | * this duty, then the jiffies update is still serialized by |
Thomas Gleixner | 9c3f9e2 | 2012-11-21 20:31:52 +0100 | [diff] [blame] | 122 | * jiffies_lock. |
Frederic Weisbecker | 5bb9622 | 2012-10-15 02:03:27 +0200 | [diff] [blame] | 123 | */ |
Frederic Weisbecker | a382bf9 | 2012-12-18 18:24:35 +0100 | [diff] [blame] | 124 | if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE) |
Frederic Weisbecker | c5bfece | 2013-04-12 16:45:34 +0200 | [diff] [blame] | 125 | && !tick_nohz_full_cpu(cpu)) |
Frederic Weisbecker | 5bb9622 | 2012-10-15 02:03:27 +0200 | [diff] [blame] | 126 | tick_do_timer_cpu = cpu; |
| 127 | #endif |
| 128 | |
| 129 | /* Check, if the jiffies need an update */ |
| 130 | if (tick_do_timer_cpu == cpu) |
| 131 | tick_do_update_jiffies64(now); |
| 132 | } |
| 133 | |
Frederic Weisbecker | 9e8f559 | 2012-10-15 02:43:03 +0200 | [diff] [blame] | 134 | static void tick_sched_handle(struct tick_sched *ts, struct pt_regs *regs) |
| 135 | { |
Frederic Weisbecker | 3451d02 | 2011-08-10 23:21:01 +0200 | [diff] [blame] | 136 | #ifdef CONFIG_NO_HZ_COMMON |
Frederic Weisbecker | 9e8f559 | 2012-10-15 02:43:03 +0200 | [diff] [blame] | 137 | /* |
| 138 | * When we are idle and the tick is stopped, we have to touch |
| 139 | * the watchdog as we might not schedule for a really long |
| 140 | * time. This happens on complete idle SMP systems while |
| 141 | * waiting on the login prompt. We also increment the "start of |
| 142 | * idle" jiffy stamp so the idle accounting adjustment we do |
| 143 | * when we go busy again does not account too much ticks. |
| 144 | */ |
| 145 | if (ts->tick_stopped) { |
| 146 | touch_softlockup_watchdog(); |
| 147 | if (is_idle_task(current)) |
| 148 | ts->idle_jiffies++; |
| 149 | } |
Frederic Weisbecker | 94a5714 | 2012-10-15 16:17:16 +0200 | [diff] [blame] | 150 | #endif |
Frederic Weisbecker | 9e8f559 | 2012-10-15 02:43:03 +0200 | [diff] [blame] | 151 | update_process_times(user_mode(regs)); |
| 152 | profile_tick(CPU_PROFILING); |
| 153 | } |
| 154 | |
Frederic Weisbecker | c5bfece | 2013-04-12 16:45:34 +0200 | [diff] [blame] | 155 | #ifdef CONFIG_NO_HZ_FULL |
Frederic Weisbecker | 460775d | 2013-07-24 23:52:27 +0200 | [diff] [blame] | 156 | cpumask_var_t tick_nohz_full_mask; |
Paul E. McKenney | c0f489d | 2014-06-04 13:46:03 -0700 | [diff] [blame] | 157 | cpumask_var_t housekeeping_mask; |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 158 | bool tick_nohz_full_running; |
Frederic Weisbecker | a831881 | 2012-12-18 17:32:19 +0100 | [diff] [blame] | 159 | |
Frederic Weisbecker | 9014c45 | 2013-04-20 15:43:57 +0200 | [diff] [blame] | 160 | static bool can_stop_full_tick(void) |
| 161 | { |
| 162 | WARN_ON_ONCE(!irqs_disabled()); |
| 163 | |
Frederic Weisbecker | cb41a29 | 2013-04-20 17:35:50 +0200 | [diff] [blame] | 164 | if (!sched_can_stop_tick()) { |
| 165 | trace_tick_stop(0, "more than 1 task in runqueue\n"); |
Frederic Weisbecker | 9014c45 | 2013-04-20 15:43:57 +0200 | [diff] [blame] | 166 | return false; |
Frederic Weisbecker | cb41a29 | 2013-04-20 17:35:50 +0200 | [diff] [blame] | 167 | } |
Frederic Weisbecker | 9014c45 | 2013-04-20 15:43:57 +0200 | [diff] [blame] | 168 | |
Frederic Weisbecker | cb41a29 | 2013-04-20 17:35:50 +0200 | [diff] [blame] | 169 | if (!posix_cpu_timers_can_stop_tick(current)) { |
| 170 | trace_tick_stop(0, "posix timers running\n"); |
Frederic Weisbecker | 9014c45 | 2013-04-20 15:43:57 +0200 | [diff] [blame] | 171 | return false; |
Frederic Weisbecker | cb41a29 | 2013-04-20 17:35:50 +0200 | [diff] [blame] | 172 | } |
Frederic Weisbecker | 9014c45 | 2013-04-20 15:43:57 +0200 | [diff] [blame] | 173 | |
Frederic Weisbecker | cb41a29 | 2013-04-20 17:35:50 +0200 | [diff] [blame] | 174 | if (!perf_event_can_stop_tick()) { |
| 175 | trace_tick_stop(0, "perf events running\n"); |
Frederic Weisbecker | 9014c45 | 2013-04-20 15:43:57 +0200 | [diff] [blame] | 176 | return false; |
Frederic Weisbecker | cb41a29 | 2013-04-20 17:35:50 +0200 | [diff] [blame] | 177 | } |
Frederic Weisbecker | 9014c45 | 2013-04-20 15:43:57 +0200 | [diff] [blame] | 178 | |
| 179 | /* sched_clock_tick() needs us? */ |
| 180 | #ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK |
| 181 | /* |
| 182 | * TODO: kick full dynticks CPUs when |
| 183 | * sched_clock_stable is set. |
| 184 | */ |
Peter Zijlstra | 35af99e | 2013-11-28 19:38:42 +0100 | [diff] [blame] | 185 | if (!sched_clock_stable()) { |
Frederic Weisbecker | cb41a29 | 2013-04-20 17:35:50 +0200 | [diff] [blame] | 186 | trace_tick_stop(0, "unstable sched clock\n"); |
Steven Rostedt | e12d027 | 2013-05-10 17:12:28 -0400 | [diff] [blame] | 187 | /* |
| 188 | * Don't allow the user to think they can get |
| 189 | * full NO_HZ with this machine. |
| 190 | */ |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 191 | WARN_ONCE(tick_nohz_full_running, |
Steven Rostedt | 543487c | 2013-07-16 10:22:12 -0400 | [diff] [blame] | 192 | "NO_HZ FULL will not work with unstable sched clock"); |
Frederic Weisbecker | 9014c45 | 2013-04-20 15:43:57 +0200 | [diff] [blame] | 193 | return false; |
Frederic Weisbecker | cb41a29 | 2013-04-20 17:35:50 +0200 | [diff] [blame] | 194 | } |
Frederic Weisbecker | 9014c45 | 2013-04-20 15:43:57 +0200 | [diff] [blame] | 195 | #endif |
| 196 | |
| 197 | return true; |
| 198 | } |
| 199 | |
| 200 | static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now); |
| 201 | |
Frederic Weisbecker | 76c24fb | 2013-04-18 00:15:40 +0200 | [diff] [blame] | 202 | /* |
| 203 | * Re-evaluate the need for the tick on the current CPU |
| 204 | * and restart it if necessary. |
| 205 | */ |
Frederic Weisbecker | d13508f | 2013-07-24 23:52:27 +0200 | [diff] [blame] | 206 | void __tick_nohz_full_check(void) |
Frederic Weisbecker | 76c24fb | 2013-04-18 00:15:40 +0200 | [diff] [blame] | 207 | { |
Christoph Lameter | 22127e9 | 2014-08-17 12:30:25 -0500 | [diff] [blame] | 208 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
Frederic Weisbecker | 9014c45 | 2013-04-20 15:43:57 +0200 | [diff] [blame] | 209 | |
| 210 | if (tick_nohz_full_cpu(smp_processor_id())) { |
| 211 | if (ts->tick_stopped && !is_idle_task(current)) { |
| 212 | if (!can_stop_full_tick()) |
| 213 | tick_nohz_restart_sched_tick(ts, ktime_get()); |
| 214 | } |
| 215 | } |
Frederic Weisbecker | 76c24fb | 2013-04-18 00:15:40 +0200 | [diff] [blame] | 216 | } |
| 217 | |
| 218 | static void nohz_full_kick_work_func(struct irq_work *work) |
| 219 | { |
Frederic Weisbecker | d13508f | 2013-07-24 23:52:27 +0200 | [diff] [blame] | 220 | __tick_nohz_full_check(); |
Frederic Weisbecker | 76c24fb | 2013-04-18 00:15:40 +0200 | [diff] [blame] | 221 | } |
| 222 | |
| 223 | static DEFINE_PER_CPU(struct irq_work, nohz_full_kick_work) = { |
| 224 | .func = nohz_full_kick_work_func, |
| 225 | }; |
| 226 | |
| 227 | /* |
Frederic Weisbecker | 40bea03 | 2014-08-13 18:50:16 +0200 | [diff] [blame] | 228 | * Kick this CPU if it's full dynticks in order to force it to |
| 229 | * re-evaluate its dependency on the tick and restart it if necessary. |
| 230 | * This kick, unlike tick_nohz_full_kick_cpu() and tick_nohz_full_kick_all(), |
| 231 | * is NMI safe. |
| 232 | */ |
| 233 | void tick_nohz_full_kick(void) |
| 234 | { |
| 235 | if (!tick_nohz_full_cpu(smp_processor_id())) |
| 236 | return; |
| 237 | |
Christoph Lameter | 56e4dea | 2014-10-27 10:49:45 -0500 | [diff] [blame^] | 238 | irq_work_queue(this_cpu_ptr(&nohz_full_kick_work)); |
Frederic Weisbecker | 40bea03 | 2014-08-13 18:50:16 +0200 | [diff] [blame] | 239 | } |
| 240 | |
| 241 | /* |
Frederic Weisbecker | 3d36aeb | 2014-06-04 16:17:33 +0200 | [diff] [blame] | 242 | * Kick the CPU if it's full dynticks in order to force it to |
Frederic Weisbecker | 76c24fb | 2013-04-18 00:15:40 +0200 | [diff] [blame] | 243 | * re-evaluate its dependency on the tick and restart it if necessary. |
| 244 | */ |
Frederic Weisbecker | 3d36aeb | 2014-06-04 16:17:33 +0200 | [diff] [blame] | 245 | void tick_nohz_full_kick_cpu(int cpu) |
Frederic Weisbecker | 76c24fb | 2013-04-18 00:15:40 +0200 | [diff] [blame] | 246 | { |
Frederic Weisbecker | 3d36aeb | 2014-06-04 16:17:33 +0200 | [diff] [blame] | 247 | if (!tick_nohz_full_cpu(cpu)) |
| 248 | return; |
| 249 | |
| 250 | irq_work_queue_on(&per_cpu(nohz_full_kick_work, cpu), cpu); |
Frederic Weisbecker | 76c24fb | 2013-04-18 00:15:40 +0200 | [diff] [blame] | 251 | } |
| 252 | |
| 253 | static void nohz_full_kick_ipi(void *info) |
| 254 | { |
Frederic Weisbecker | d13508f | 2013-07-24 23:52:27 +0200 | [diff] [blame] | 255 | __tick_nohz_full_check(); |
Frederic Weisbecker | 76c24fb | 2013-04-18 00:15:40 +0200 | [diff] [blame] | 256 | } |
| 257 | |
| 258 | /* |
| 259 | * Kick all full dynticks CPUs in order to force these to re-evaluate |
| 260 | * their dependency on the tick and restart it if necessary. |
| 261 | */ |
| 262 | void tick_nohz_full_kick_all(void) |
| 263 | { |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 264 | if (!tick_nohz_full_running) |
Frederic Weisbecker | 76c24fb | 2013-04-18 00:15:40 +0200 | [diff] [blame] | 265 | return; |
| 266 | |
| 267 | preempt_disable(); |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 268 | smp_call_function_many(tick_nohz_full_mask, |
Frederic Weisbecker | 76c24fb | 2013-04-18 00:15:40 +0200 | [diff] [blame] | 269 | nohz_full_kick_ipi, NULL, false); |
Frederic Weisbecker | c2e7fcf | 2013-08-02 18:29:56 +0200 | [diff] [blame] | 270 | tick_nohz_full_kick(); |
Frederic Weisbecker | 76c24fb | 2013-04-18 00:15:40 +0200 | [diff] [blame] | 271 | preempt_enable(); |
| 272 | } |
| 273 | |
Frederic Weisbecker | 99e5ada | 2013-04-20 17:11:50 +0200 | [diff] [blame] | 274 | /* |
| 275 | * Re-evaluate the need for the tick as we switch the current task. |
| 276 | * It might need the tick due to per task/process properties: |
| 277 | * perf events, posix cpu timers, ... |
| 278 | */ |
Frederic Weisbecker | d13508f | 2013-07-24 23:52:27 +0200 | [diff] [blame] | 279 | void __tick_nohz_task_switch(struct task_struct *tsk) |
Frederic Weisbecker | 99e5ada | 2013-04-20 17:11:50 +0200 | [diff] [blame] | 280 | { |
| 281 | unsigned long flags; |
| 282 | |
Frederic Weisbecker | 99e5ada | 2013-04-20 17:11:50 +0200 | [diff] [blame] | 283 | local_irq_save(flags); |
| 284 | |
Li Zhong | 6296ace | 2013-04-28 11:25:58 +0800 | [diff] [blame] | 285 | if (!tick_nohz_full_cpu(smp_processor_id())) |
| 286 | goto out; |
| 287 | |
Frederic Weisbecker | 99e5ada | 2013-04-20 17:11:50 +0200 | [diff] [blame] | 288 | if (tick_nohz_tick_stopped() && !can_stop_full_tick()) |
| 289 | tick_nohz_full_kick(); |
| 290 | |
Li Zhong | 6296ace | 2013-04-28 11:25:58 +0800 | [diff] [blame] | 291 | out: |
Frederic Weisbecker | 99e5ada | 2013-04-20 17:11:50 +0200 | [diff] [blame] | 292 | local_irq_restore(flags); |
| 293 | } |
| 294 | |
Frederic Weisbecker | a831881 | 2012-12-18 17:32:19 +0100 | [diff] [blame] | 295 | /* Parse the boot-time nohz CPU list from the kernel parameters. */ |
Frederic Weisbecker | c5bfece | 2013-04-12 16:45:34 +0200 | [diff] [blame] | 296 | static int __init tick_nohz_full_setup(char *str) |
Frederic Weisbecker | a831881 | 2012-12-18 17:32:19 +0100 | [diff] [blame] | 297 | { |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 298 | alloc_bootmem_cpumask_var(&tick_nohz_full_mask); |
| 299 | if (cpulist_parse(str, tick_nohz_full_mask) < 0) { |
Frederic Weisbecker | c5bfece | 2013-04-12 16:45:34 +0200 | [diff] [blame] | 300 | pr_warning("NOHZ: Incorrect nohz_full cpumask\n"); |
Frederic Weisbecker | 4327b15 | 2014-08-17 22:02:55 +0200 | [diff] [blame] | 301 | free_bootmem_cpumask_var(tick_nohz_full_mask); |
Frederic Weisbecker | 0453b43 | 2013-03-27 02:18:34 +0100 | [diff] [blame] | 302 | return 1; |
| 303 | } |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 304 | tick_nohz_full_running = true; |
Frederic Weisbecker | 0453b43 | 2013-03-27 02:18:34 +0100 | [diff] [blame] | 305 | |
Frederic Weisbecker | a831881 | 2012-12-18 17:32:19 +0100 | [diff] [blame] | 306 | return 1; |
| 307 | } |
Frederic Weisbecker | c5bfece | 2013-04-12 16:45:34 +0200 | [diff] [blame] | 308 | __setup("nohz_full=", tick_nohz_full_setup); |
Frederic Weisbecker | a831881 | 2012-12-18 17:32:19 +0100 | [diff] [blame] | 309 | |
Paul Gortmaker | 0db0628 | 2013-06-19 14:53:51 -0400 | [diff] [blame] | 310 | static int tick_nohz_cpu_down_callback(struct notifier_block *nfb, |
Frederic Weisbecker | a382bf9 | 2012-12-18 18:24:35 +0100 | [diff] [blame] | 311 | unsigned long action, |
| 312 | void *hcpu) |
| 313 | { |
| 314 | unsigned int cpu = (unsigned long)hcpu; |
| 315 | |
| 316 | switch (action & ~CPU_TASKS_FROZEN) { |
| 317 | case CPU_DOWN_PREPARE: |
| 318 | /* |
| 319 | * If we handle the timekeeping duty for full dynticks CPUs, |
| 320 | * we can't safely shutdown that CPU. |
| 321 | */ |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 322 | if (tick_nohz_full_running && tick_do_timer_cpu == cpu) |
Li Zhong | 1a7f829 | 2013-05-17 16:44:04 +0800 | [diff] [blame] | 323 | return NOTIFY_BAD; |
Frederic Weisbecker | a382bf9 | 2012-12-18 18:24:35 +0100 | [diff] [blame] | 324 | break; |
| 325 | } |
| 326 | return NOTIFY_OK; |
| 327 | } |
| 328 | |
Frederic Weisbecker | 1034fc2 | 2013-03-26 15:04:50 +0100 | [diff] [blame] | 329 | /* |
| 330 | * Worst case string length in chunks of CPU range seems 2 steps |
| 331 | * separations: 0,2,4,6,... |
| 332 | * This is NR_CPUS + sizeof('\0') |
| 333 | */ |
Frederic Weisbecker | c5bfece | 2013-04-12 16:45:34 +0200 | [diff] [blame] | 334 | static char __initdata nohz_full_buf[NR_CPUS + 1]; |
Frederic Weisbecker | 1034fc2 | 2013-03-26 15:04:50 +0100 | [diff] [blame] | 335 | |
Frederic Weisbecker | f98823a | 2013-03-27 01:17:22 +0100 | [diff] [blame] | 336 | static int tick_nohz_init_all(void) |
| 337 | { |
| 338 | int err = -1; |
| 339 | |
| 340 | #ifdef CONFIG_NO_HZ_FULL_ALL |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 341 | if (!alloc_cpumask_var(&tick_nohz_full_mask, GFP_KERNEL)) { |
Frederic Weisbecker | 4327b15 | 2014-08-17 22:02:55 +0200 | [diff] [blame] | 342 | WARN(1, "NO_HZ: Can't allocate full dynticks cpumask\n"); |
Paul E. McKenney | c0f489d | 2014-06-04 13:46:03 -0700 | [diff] [blame] | 343 | return err; |
| 344 | } |
Frederic Weisbecker | f98823a | 2013-03-27 01:17:22 +0100 | [diff] [blame] | 345 | err = 0; |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 346 | cpumask_setall(tick_nohz_full_mask); |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 347 | tick_nohz_full_running = true; |
Frederic Weisbecker | f98823a | 2013-03-27 01:17:22 +0100 | [diff] [blame] | 348 | #endif |
| 349 | return err; |
| 350 | } |
| 351 | |
Frederic Weisbecker | d1e43fa | 2013-03-26 23:47:24 +0100 | [diff] [blame] | 352 | void __init tick_nohz_init(void) |
Frederic Weisbecker | a831881 | 2012-12-18 17:32:19 +0100 | [diff] [blame] | 353 | { |
Frederic Weisbecker | d1e43fa | 2013-03-26 23:47:24 +0100 | [diff] [blame] | 354 | int cpu; |
| 355 | |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 356 | if (!tick_nohz_full_running) { |
Frederic Weisbecker | f98823a | 2013-03-27 01:17:22 +0100 | [diff] [blame] | 357 | if (tick_nohz_init_all() < 0) |
| 358 | return; |
| 359 | } |
Frederic Weisbecker | d1e43fa | 2013-03-26 23:47:24 +0100 | [diff] [blame] | 360 | |
Frederic Weisbecker | 4327b15 | 2014-08-17 22:02:55 +0200 | [diff] [blame] | 361 | if (!alloc_cpumask_var(&housekeeping_mask, GFP_KERNEL)) { |
| 362 | WARN(1, "NO_HZ: Can't allocate not-full dynticks cpumask\n"); |
| 363 | cpumask_clear(tick_nohz_full_mask); |
| 364 | tick_nohz_full_running = false; |
| 365 | return; |
| 366 | } |
| 367 | |
Frederic Weisbecker | 9b01f5b | 2014-08-18 01:36:07 +0200 | [diff] [blame] | 368 | /* |
| 369 | * Full dynticks uses irq work to drive the tick rescheduling on safe |
| 370 | * locking contexts. But then we need irq work to raise its own |
| 371 | * interrupts to avoid circular dependency on the tick |
| 372 | */ |
| 373 | if (!arch_irq_work_has_interrupt()) { |
| 374 | pr_warning("NO_HZ: Can't run full dynticks because arch doesn't " |
| 375 | "support irq work self-IPIs\n"); |
| 376 | cpumask_clear(tick_nohz_full_mask); |
| 377 | cpumask_copy(housekeeping_mask, cpu_possible_mask); |
| 378 | tick_nohz_full_running = false; |
| 379 | return; |
| 380 | } |
| 381 | |
Frederic Weisbecker | 4327b15 | 2014-08-17 22:02:55 +0200 | [diff] [blame] | 382 | cpu = smp_processor_id(); |
| 383 | |
| 384 | if (cpumask_test_cpu(cpu, tick_nohz_full_mask)) { |
| 385 | pr_warning("NO_HZ: Clearing %d from nohz_full range for timekeeping\n", cpu); |
| 386 | cpumask_clear_cpu(cpu, tick_nohz_full_mask); |
| 387 | } |
| 388 | |
| 389 | cpumask_andnot(housekeeping_mask, |
| 390 | cpu_possible_mask, tick_nohz_full_mask); |
| 391 | |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 392 | for_each_cpu(cpu, tick_nohz_full_mask) |
Frederic Weisbecker | 2e70933 | 2013-07-10 00:55:25 +0200 | [diff] [blame] | 393 | context_tracking_cpu_set(cpu); |
| 394 | |
Frederic Weisbecker | d1e43fa | 2013-03-26 23:47:24 +0100 | [diff] [blame] | 395 | cpu_notifier(tick_nohz_cpu_down_callback, 0); |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 396 | cpulist_scnprintf(nohz_full_buf, sizeof(nohz_full_buf), tick_nohz_full_mask); |
Frederic Weisbecker | c5bfece | 2013-04-12 16:45:34 +0200 | [diff] [blame] | 397 | pr_info("NO_HZ: Full dynticks CPUs: %s.\n", nohz_full_buf); |
Frederic Weisbecker | a831881 | 2012-12-18 17:32:19 +0100 | [diff] [blame] | 398 | } |
Frederic Weisbecker | a831881 | 2012-12-18 17:32:19 +0100 | [diff] [blame] | 399 | #endif |
| 400 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 401 | /* |
| 402 | * NOHZ - aka dynamic tick functionality |
| 403 | */ |
Frederic Weisbecker | 3451d02 | 2011-08-10 23:21:01 +0200 | [diff] [blame] | 404 | #ifdef CONFIG_NO_HZ_COMMON |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 405 | /* |
| 406 | * NO HZ enabled ? |
| 407 | */ |
Thomas Gleixner | d689fe2 | 2013-11-13 21:01:57 +0100 | [diff] [blame] | 408 | static int tick_nohz_enabled __read_mostly = 1; |
| 409 | int tick_nohz_active __read_mostly; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 410 | /* |
| 411 | * Enable / Disable tickless mode |
| 412 | */ |
| 413 | static int __init setup_tick_nohz(char *str) |
| 414 | { |
| 415 | if (!strcmp(str, "off")) |
| 416 | tick_nohz_enabled = 0; |
| 417 | else if (!strcmp(str, "on")) |
| 418 | tick_nohz_enabled = 1; |
| 419 | else |
| 420 | return 0; |
| 421 | return 1; |
| 422 | } |
| 423 | |
| 424 | __setup("nohz=", setup_tick_nohz); |
| 425 | |
| 426 | /** |
| 427 | * tick_nohz_update_jiffies - update jiffies when idle was interrupted |
| 428 | * |
| 429 | * Called from interrupt entry when the CPU was idle |
| 430 | * |
| 431 | * In case the sched_tick was stopped on this CPU, we have to check if jiffies |
| 432 | * must be updated. Otherwise an interrupt handler could use a stale jiffy |
| 433 | * value. We do this unconditionally on any cpu, as we don't know whether the |
| 434 | * cpu, which has the update task assigned is in a long sleep. |
| 435 | */ |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 436 | static void tick_nohz_update_jiffies(ktime_t now) |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 437 | { |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 438 | unsigned long flags; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 439 | |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 440 | __this_cpu_write(tick_cpu_sched.idle_waketime, now); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 441 | |
| 442 | local_irq_save(flags); |
| 443 | tick_do_update_jiffies64(now); |
| 444 | local_irq_restore(flags); |
Ingo Molnar | 02ff375 | 2008-05-12 15:43:53 +0200 | [diff] [blame] | 445 | |
| 446 | touch_softlockup_watchdog(); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 447 | } |
| 448 | |
Arjan van de Ven | 595aac4 | 2010-05-09 08:22:45 -0700 | [diff] [blame] | 449 | /* |
| 450 | * Updates the per cpu time idle statistics counters |
| 451 | */ |
Arjan van de Ven | 8d63bf9 | 2010-05-09 08:24:03 -0700 | [diff] [blame] | 452 | static void |
Peter Zijlstra | 8c215bd | 2010-07-01 09:07:17 +0200 | [diff] [blame] | 453 | 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] | 454 | { |
| 455 | ktime_t delta; |
| 456 | |
Arjan van de Ven | 595aac4 | 2010-05-09 08:22:45 -0700 | [diff] [blame] | 457 | if (ts->idle_active) { |
| 458 | delta = ktime_sub(now, ts->idle_entrytime); |
Peter Zijlstra | 8c215bd | 2010-07-01 09:07:17 +0200 | [diff] [blame] | 459 | if (nr_iowait_cpu(cpu) > 0) |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 460 | ts->iowait_sleeptime = ktime_add(ts->iowait_sleeptime, delta); |
Michal Hocko | 6beea0c | 2011-08-24 09:37:48 +0200 | [diff] [blame] | 461 | else |
| 462 | ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta); |
Arjan van de Ven | 8c7b09f | 2010-05-09 08:23:23 -0700 | [diff] [blame] | 463 | ts->idle_entrytime = now; |
Arjan van de Ven | 595aac4 | 2010-05-09 08:22:45 -0700 | [diff] [blame] | 464 | } |
Arjan van de Ven | 8d63bf9 | 2010-05-09 08:24:03 -0700 | [diff] [blame] | 465 | |
Arjan van de Ven | e0e37c2 | 2010-05-09 08:24:39 -0700 | [diff] [blame] | 466 | if (last_update_time) |
Arjan van de Ven | 8d63bf9 | 2010-05-09 08:24:03 -0700 | [diff] [blame] | 467 | *last_update_time = ktime_to_us(now); |
| 468 | |
Arjan van de Ven | 595aac4 | 2010-05-09 08:22:45 -0700 | [diff] [blame] | 469 | } |
| 470 | |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 471 | static void tick_nohz_stop_idle(struct tick_sched *ts, ktime_t now) |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 472 | { |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 473 | update_ts_time_stats(smp_processor_id(), ts, now, NULL); |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 474 | ts->idle_active = 0; |
Peter Zijlstra | 56c7426 | 2008-09-01 16:44:23 +0200 | [diff] [blame] | 475 | |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 476 | sched_clock_idle_wakeup_event(0); |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 477 | } |
| 478 | |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 479 | static ktime_t tick_nohz_start_idle(struct tick_sched *ts) |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 480 | { |
Michal Hocko | 430ee88 | 2011-12-01 17:00:22 +0100 | [diff] [blame] | 481 | ktime_t now = ktime_get(); |
Arjan van de Ven | 595aac4 | 2010-05-09 08:22:45 -0700 | [diff] [blame] | 482 | |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 483 | ts->idle_entrytime = now; |
| 484 | ts->idle_active = 1; |
Peter Zijlstra | 56c7426 | 2008-09-01 16:44:23 +0200 | [diff] [blame] | 485 | sched_clock_idle_sleep_event(); |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 486 | return now; |
| 487 | } |
| 488 | |
Arjan van de Ven | b1f724c | 2010-05-09 08:22:08 -0700 | [diff] [blame] | 489 | /** |
| 490 | * get_cpu_idle_time_us - get the total idle time of a cpu |
| 491 | * @cpu: CPU number to query |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 492 | * @last_update_time: variable to store update time in. Do not update |
| 493 | * counters if NULL. |
Arjan van de Ven | b1f724c | 2010-05-09 08:22:08 -0700 | [diff] [blame] | 494 | * |
| 495 | * Return the cummulative idle time (since boot) for a given |
Michal Hocko | 6beea0c | 2011-08-24 09:37:48 +0200 | [diff] [blame] | 496 | * CPU, in microseconds. |
Arjan van de Ven | b1f724c | 2010-05-09 08:22:08 -0700 | [diff] [blame] | 497 | * |
| 498 | * This time is measured via accounting rather than sampling, |
| 499 | * and is as accurate as ktime_get() is. |
| 500 | * |
| 501 | * This function returns -1 if NOHZ is not enabled. |
| 502 | */ |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 503 | u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time) |
| 504 | { |
| 505 | struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 506 | ktime_t now, idle; |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 507 | |
Thomas Gleixner | d689fe2 | 2013-11-13 21:01:57 +0100 | [diff] [blame] | 508 | if (!tick_nohz_active) |
venkatesh.pallipadi@intel.com | 8083e4a | 2008-08-04 11:59:11 -0700 | [diff] [blame] | 509 | return -1; |
| 510 | |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 511 | now = ktime_get(); |
| 512 | if (last_update_time) { |
| 513 | update_ts_time_stats(cpu, ts, now, last_update_time); |
| 514 | idle = ts->idle_sleeptime; |
| 515 | } else { |
| 516 | if (ts->idle_active && !nr_iowait_cpu(cpu)) { |
| 517 | ktime_t delta = ktime_sub(now, ts->idle_entrytime); |
venkatesh.pallipadi@intel.com | 8083e4a | 2008-08-04 11:59:11 -0700 | [diff] [blame] | 518 | |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 519 | idle = ktime_add(ts->idle_sleeptime, delta); |
| 520 | } else { |
| 521 | idle = ts->idle_sleeptime; |
| 522 | } |
| 523 | } |
| 524 | |
| 525 | return ktime_to_us(idle); |
| 526 | |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 527 | } |
venkatesh.pallipadi@intel.com | 8083e4a | 2008-08-04 11:59:11 -0700 | [diff] [blame] | 528 | EXPORT_SYMBOL_GPL(get_cpu_idle_time_us); |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 529 | |
Michal Hocko | 6beea0c | 2011-08-24 09:37:48 +0200 | [diff] [blame] | 530 | /** |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 531 | * get_cpu_iowait_time_us - get the total iowait time of a cpu |
| 532 | * @cpu: CPU number to query |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 533 | * @last_update_time: variable to store update time in. Do not update |
| 534 | * counters if NULL. |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 535 | * |
| 536 | * Return the cummulative iowait time (since boot) for a given |
| 537 | * CPU, in microseconds. |
| 538 | * |
| 539 | * This time is measured via accounting rather than sampling, |
| 540 | * and is as accurate as ktime_get() is. |
| 541 | * |
| 542 | * This function returns -1 if NOHZ is not enabled. |
| 543 | */ |
| 544 | u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time) |
| 545 | { |
| 546 | struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 547 | ktime_t now, iowait; |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 548 | |
Thomas Gleixner | d689fe2 | 2013-11-13 21:01:57 +0100 | [diff] [blame] | 549 | if (!tick_nohz_active) |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 550 | return -1; |
| 551 | |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 552 | now = ktime_get(); |
| 553 | if (last_update_time) { |
| 554 | update_ts_time_stats(cpu, ts, now, last_update_time); |
| 555 | iowait = ts->iowait_sleeptime; |
| 556 | } else { |
| 557 | if (ts->idle_active && nr_iowait_cpu(cpu) > 0) { |
| 558 | ktime_t delta = ktime_sub(now, ts->idle_entrytime); |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 559 | |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 560 | iowait = ktime_add(ts->iowait_sleeptime, delta); |
| 561 | } else { |
| 562 | iowait = ts->iowait_sleeptime; |
| 563 | } |
| 564 | } |
| 565 | |
| 566 | return ktime_to_us(iowait); |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 567 | } |
| 568 | EXPORT_SYMBOL_GPL(get_cpu_iowait_time_us); |
| 569 | |
Frederic Weisbecker | 84bf1bc | 2011-08-01 01:25:38 +0200 | [diff] [blame] | 570 | static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts, |
| 571 | ktime_t now, int cpu) |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 572 | { |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 573 | unsigned long seq, last_jiffies, next_jiffies, delta_jiffies; |
Frederic Weisbecker | 84bf1bc | 2011-08-01 01:25:38 +0200 | [diff] [blame] | 574 | ktime_t last_update, expires, ret = { .tv64 = 0 }; |
Paul E. McKenney | aa9b1630 | 2012-05-10 16:41:44 -0700 | [diff] [blame] | 575 | unsigned long rcu_delta_jiffies; |
Christoph Lameter | 22127e9 | 2014-08-17 12:30:25 -0500 | [diff] [blame] | 576 | struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev); |
Jon Hunter | 9896246 | 2009-08-18 12:45:10 -0500 | [diff] [blame] | 577 | u64 time_delta; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 578 | |
Frederic Weisbecker | 855a0fc | 2013-12-17 00:16:37 +0100 | [diff] [blame] | 579 | time_delta = timekeeping_max_deferment(); |
| 580 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 581 | /* Read jiffies and the time when jiffies were updated last */ |
| 582 | do { |
John Stultz | d6ad418 | 2012-02-28 16:50:11 -0800 | [diff] [blame] | 583 | seq = read_seqbegin(&jiffies_lock); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 584 | last_update = last_jiffies_update; |
| 585 | last_jiffies = jiffies; |
John Stultz | d6ad418 | 2012-02-28 16:50:11 -0800 | [diff] [blame] | 586 | } while (read_seqretry(&jiffies_lock, seq)); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 587 | |
Frederic Weisbecker | 74876a9 | 2012-10-12 18:00:23 +0200 | [diff] [blame] | 588 | if (rcu_needs_cpu(cpu, &rcu_delta_jiffies) || |
Martin Schwidefsky | fe0f497 | 2014-09-30 17:37:52 +0200 | [diff] [blame] | 589 | arch_needs_cpu() || irq_work_needs_cpu()) { |
Martin Schwidefsky | 3c5d92a | 2009-09-29 14:25:16 +0200 | [diff] [blame] | 590 | next_jiffies = last_jiffies + 1; |
Ingo Molnar | 6ba9b34 | 2007-02-19 18:11:56 +0000 | [diff] [blame] | 591 | delta_jiffies = 1; |
Martin Schwidefsky | 3c5d92a | 2009-09-29 14:25:16 +0200 | [diff] [blame] | 592 | } else { |
| 593 | /* Get the next timer wheel timer */ |
| 594 | next_jiffies = get_next_timer_interrupt(last_jiffies); |
| 595 | delta_jiffies = next_jiffies - last_jiffies; |
Paul E. McKenney | aa9b1630 | 2012-05-10 16:41:44 -0700 | [diff] [blame] | 596 | if (rcu_delta_jiffies < delta_jiffies) { |
| 597 | next_jiffies = last_jiffies + rcu_delta_jiffies; |
| 598 | delta_jiffies = rcu_delta_jiffies; |
| 599 | } |
Martin Schwidefsky | 3c5d92a | 2009-09-29 14:25:16 +0200 | [diff] [blame] | 600 | } |
Ingo Molnar | 47aa8b6 | 2013-04-26 10:05:59 +0200 | [diff] [blame] | 601 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 602 | /* |
Ingo Molnar | 47aa8b6 | 2013-04-26 10:05:59 +0200 | [diff] [blame] | 603 | * Do not stop the tick, if we are only one off (or less) |
| 604 | * or if the cpu is required for RCU: |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 605 | */ |
Ingo Molnar | 47aa8b6 | 2013-04-26 10:05:59 +0200 | [diff] [blame] | 606 | if (!ts->tick_stopped && delta_jiffies <= 1) |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 607 | goto out; |
| 608 | |
| 609 | /* Schedule the tick, if we are at least one jiffie off */ |
| 610 | if ((long)delta_jiffies >= 1) { |
| 611 | |
Woodruff, Richard | 0014744 | 2008-12-01 14:18:11 -0800 | [diff] [blame] | 612 | /* |
Woodruff, Richard | 0014744 | 2008-12-01 14:18:11 -0800 | [diff] [blame] | 613 | * If this cpu is the one which updates jiffies, then |
| 614 | * give up the assignment and let it be taken by the |
| 615 | * cpu which runs the tick timer next, which might be |
| 616 | * this cpu as well. If we don't drop this here the |
| 617 | * jiffies might be stale and do_timer() never |
Thomas Gleixner | 2718501 | 2009-11-12 22:12:06 +0100 | [diff] [blame] | 618 | * invoked. Keep track of the fact that it was the one |
| 619 | * which had the do_timer() duty last. If this cpu is |
| 620 | * the one which had the do_timer() duty last, we |
| 621 | * limit the sleep time to the timekeeping |
| 622 | * max_deferement value which we retrieved |
| 623 | * above. Otherwise we can sleep as long as we want. |
Woodruff, Richard | 0014744 | 2008-12-01 14:18:11 -0800 | [diff] [blame] | 624 | */ |
Thomas Gleixner | 2718501 | 2009-11-12 22:12:06 +0100 | [diff] [blame] | 625 | if (cpu == tick_do_timer_cpu) { |
Woodruff, Richard | 0014744 | 2008-12-01 14:18:11 -0800 | [diff] [blame] | 626 | tick_do_timer_cpu = TICK_DO_TIMER_NONE; |
Thomas Gleixner | 2718501 | 2009-11-12 22:12:06 +0100 | [diff] [blame] | 627 | ts->do_timer_last = 1; |
| 628 | } else if (tick_do_timer_cpu != TICK_DO_TIMER_NONE) { |
| 629 | time_delta = KTIME_MAX; |
| 630 | ts->do_timer_last = 0; |
| 631 | } else if (!ts->do_timer_last) { |
| 632 | time_delta = KTIME_MAX; |
| 633 | } |
| 634 | |
Frederic Weisbecker | 265f22a | 2013-05-03 03:39:05 +0200 | [diff] [blame] | 635 | #ifdef CONFIG_NO_HZ_FULL |
| 636 | if (!ts->inidle) { |
| 637 | time_delta = min(time_delta, |
| 638 | scheduler_tick_max_deferment()); |
| 639 | } |
| 640 | #endif |
| 641 | |
Thomas Gleixner | 2718501 | 2009-11-12 22:12:06 +0100 | [diff] [blame] | 642 | /* |
Jon Hunter | 9896246 | 2009-08-18 12:45:10 -0500 | [diff] [blame] | 643 | * calculate the expiry time for the next timer wheel |
| 644 | * timer. delta_jiffies >= NEXT_TIMER_MAX_DELTA signals |
| 645 | * that there is no timer pending or at least extremely |
| 646 | * far into the future (12 days for HZ=1000). In this |
| 647 | * case we set the expiry to the end of time. |
| 648 | */ |
| 649 | if (likely(delta_jiffies < NEXT_TIMER_MAX_DELTA)) { |
| 650 | /* |
| 651 | * Calculate the time delta for the next timer event. |
| 652 | * If the time delta exceeds the maximum time delta |
| 653 | * permitted by the current clocksource then adjust |
| 654 | * the time delta accordingly to ensure the |
| 655 | * clocksource does not wrap. |
| 656 | */ |
| 657 | time_delta = min_t(u64, time_delta, |
| 658 | tick_period.tv64 * delta_jiffies); |
Jon Hunter | 9896246 | 2009-08-18 12:45:10 -0500 | [diff] [blame] | 659 | } |
Woodruff, Richard | 0014744 | 2008-12-01 14:18:11 -0800 | [diff] [blame] | 660 | |
Thomas Gleixner | 2718501 | 2009-11-12 22:12:06 +0100 | [diff] [blame] | 661 | if (time_delta < KTIME_MAX) |
| 662 | expires = ktime_add_ns(last_update, time_delta); |
| 663 | else |
| 664 | expires.tv64 = KTIME_MAX; |
Woodruff, Richard | 0014744 | 2008-12-01 14:18:11 -0800 | [diff] [blame] | 665 | |
Woodruff, Richard | 0014744 | 2008-12-01 14:18:11 -0800 | [diff] [blame] | 666 | /* Skip reprogram of event if its not changed */ |
| 667 | if (ts->tick_stopped && ktime_equal(expires, dev->next_event)) |
| 668 | goto out; |
| 669 | |
Frederic Weisbecker | 84bf1bc | 2011-08-01 01:25:38 +0200 | [diff] [blame] | 670 | ret = expires; |
| 671 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 672 | /* |
| 673 | * nohz_stop_sched_tick can be called several times before |
| 674 | * the nohz_restart_sched_tick is called. This happens when |
| 675 | * interrupts arrive which do not cause a reschedule. In the |
| 676 | * first call we save the current tick time, so we can restart |
| 677 | * the scheduler tick in nohz_restart_sched_tick. |
| 678 | */ |
| 679 | if (!ts->tick_stopped) { |
Alex Shi | c1cc017 | 2012-09-10 15:10:58 +0800 | [diff] [blame] | 680 | nohz_balance_enter_idle(cpu); |
Peter Zijlstra | 5167e8d | 2012-06-22 15:52:09 +0200 | [diff] [blame] | 681 | calc_load_enter_idle(); |
Siddha, Suresh B | 46cb4b7 | 2007-05-08 00:32:51 -0700 | [diff] [blame] | 682 | |
Frederic Weisbecker | f5d411c | 2011-07-31 17:44:12 +0200 | [diff] [blame] | 683 | ts->last_tick = hrtimer_get_expires(&ts->sched_timer); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 684 | ts->tick_stopped = 1; |
Frederic Weisbecker | cb41a29 | 2013-04-20 17:35:50 +0200 | [diff] [blame] | 685 | trace_tick_stop(1, " "); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 686 | } |
Thomas Gleixner | d3ed782 | 2007-05-08 00:30:03 -0700 | [diff] [blame] | 687 | |
Thomas Gleixner | eaad084 | 2007-05-29 23:47:39 +0200 | [diff] [blame] | 688 | /* |
Jon Hunter | 9896246 | 2009-08-18 12:45:10 -0500 | [diff] [blame] | 689 | * If the expiration time == KTIME_MAX, then |
| 690 | * in this case we simply stop the tick timer. |
Thomas Gleixner | eaad084 | 2007-05-29 23:47:39 +0200 | [diff] [blame] | 691 | */ |
Jon Hunter | 9896246 | 2009-08-18 12:45:10 -0500 | [diff] [blame] | 692 | if (unlikely(expires.tv64 == KTIME_MAX)) { |
Thomas Gleixner | eaad084 | 2007-05-29 23:47:39 +0200 | [diff] [blame] | 693 | if (ts->nohz_mode == NOHZ_MODE_HIGHRES) |
| 694 | hrtimer_cancel(&ts->sched_timer); |
| 695 | goto out; |
| 696 | } |
| 697 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 698 | if (ts->nohz_mode == NOHZ_MODE_HIGHRES) { |
| 699 | hrtimer_start(&ts->sched_timer, expires, |
Arun R Bharadwaj | 5c33386 | 2009-04-16 12:14:37 +0530 | [diff] [blame] | 700 | HRTIMER_MODE_ABS_PINNED); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 701 | /* Check, if the timer was already in the past */ |
| 702 | if (hrtimer_active(&ts->sched_timer)) |
| 703 | goto out; |
Pavel Machek | 4c9dc64 | 2008-01-30 13:30:00 +0100 | [diff] [blame] | 704 | } else if (!tick_program_event(expires, 0)) |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 705 | goto out; |
| 706 | /* |
| 707 | * We are past the event already. So we crossed a |
| 708 | * jiffie boundary. Update jiffies and raise the |
| 709 | * softirq. |
| 710 | */ |
| 711 | tick_do_update_jiffies64(ktime_get()); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 712 | } |
| 713 | raise_softirq_irqoff(TIMER_SOFTIRQ); |
| 714 | out: |
| 715 | ts->next_jiffies = next_jiffies; |
| 716 | ts->last_jiffies = last_jiffies; |
Len Brown | 4f86d3a | 2007-10-03 18:58:00 -0400 | [diff] [blame] | 717 | ts->sleep_length = ktime_sub(dev->next_event, now); |
Frederic Weisbecker | 84bf1bc | 2011-08-01 01:25:38 +0200 | [diff] [blame] | 718 | |
| 719 | return ret; |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 720 | } |
| 721 | |
Frederic Weisbecker | 5811d99 | 2013-04-20 16:40:31 +0200 | [diff] [blame] | 722 | static void tick_nohz_full_stop_tick(struct tick_sched *ts) |
| 723 | { |
| 724 | #ifdef CONFIG_NO_HZ_FULL |
Alex Shi | e9a2eb4 | 2013-11-28 14:27:11 +0800 | [diff] [blame] | 725 | int cpu = smp_processor_id(); |
Frederic Weisbecker | 5811d99 | 2013-04-20 16:40:31 +0200 | [diff] [blame] | 726 | |
Alex Shi | e9a2eb4 | 2013-11-28 14:27:11 +0800 | [diff] [blame] | 727 | if (!tick_nohz_full_cpu(cpu) || is_idle_task(current)) |
| 728 | return; |
Frederic Weisbecker | 5811d99 | 2013-04-20 16:40:31 +0200 | [diff] [blame] | 729 | |
Alex Shi | e9a2eb4 | 2013-11-28 14:27:11 +0800 | [diff] [blame] | 730 | if (!ts->tick_stopped && ts->nohz_mode == NOHZ_MODE_INACTIVE) |
| 731 | return; |
Frederic Weisbecker | 5811d99 | 2013-04-20 16:40:31 +0200 | [diff] [blame] | 732 | |
Alex Shi | e9a2eb4 | 2013-11-28 14:27:11 +0800 | [diff] [blame] | 733 | if (!can_stop_full_tick()) |
| 734 | return; |
Frederic Weisbecker | 5811d99 | 2013-04-20 16:40:31 +0200 | [diff] [blame] | 735 | |
Alex Shi | e9a2eb4 | 2013-11-28 14:27:11 +0800 | [diff] [blame] | 736 | tick_nohz_stop_sched_tick(ts, ktime_get(), cpu); |
Frederic Weisbecker | 5811d99 | 2013-04-20 16:40:31 +0200 | [diff] [blame] | 737 | #endif |
| 738 | } |
| 739 | |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 740 | static bool can_stop_idle_tick(int cpu, struct tick_sched *ts) |
| 741 | { |
| 742 | /* |
| 743 | * If this cpu is offline and it is the one which updates |
| 744 | * jiffies, then give up the assignment and let it be taken by |
| 745 | * the cpu which runs the tick timer next. If we don't drop |
| 746 | * this here the jiffies might be stale and do_timer() never |
| 747 | * invoked. |
| 748 | */ |
| 749 | if (unlikely(!cpu_online(cpu))) { |
| 750 | if (cpu == tick_do_timer_cpu) |
| 751 | tick_do_timer_cpu = TICK_DO_TIMER_NONE; |
Thomas Gleixner | f7ea0fd | 2013-05-13 21:40:27 +0200 | [diff] [blame] | 752 | return false; |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 753 | } |
| 754 | |
Thomas Gleixner | 0e576acb | 2013-11-29 12:18:13 +0100 | [diff] [blame] | 755 | if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE)) { |
| 756 | ts->sleep_length = (ktime_t) { .tv64 = NSEC_PER_SEC/HZ }; |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 757 | return false; |
Thomas Gleixner | 0e576acb | 2013-11-29 12:18:13 +0100 | [diff] [blame] | 758 | } |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 759 | |
| 760 | if (need_resched()) |
| 761 | return false; |
| 762 | |
| 763 | if (unlikely(local_softirq_pending() && cpu_online(cpu))) { |
| 764 | static int ratelimit; |
| 765 | |
Paul E. McKenney | 803b0eb | 2012-08-23 08:34:07 -0700 | [diff] [blame] | 766 | if (ratelimit < 10 && |
| 767 | (local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK)) { |
Rado Vrbovsky | cfea7d7 | 2013-02-08 12:37:30 -0500 | [diff] [blame] | 768 | pr_warn("NOHZ: local_softirq_pending %02x\n", |
| 769 | (unsigned int) local_softirq_pending()); |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 770 | ratelimit++; |
| 771 | } |
| 772 | return false; |
| 773 | } |
| 774 | |
Frederic Weisbecker | 460775d | 2013-07-24 23:52:27 +0200 | [diff] [blame] | 775 | if (tick_nohz_full_enabled()) { |
Frederic Weisbecker | a382bf9 | 2012-12-18 18:24:35 +0100 | [diff] [blame] | 776 | /* |
| 777 | * Keep the tick alive to guarantee timekeeping progression |
| 778 | * if there are full dynticks CPUs around |
| 779 | */ |
| 780 | if (tick_do_timer_cpu == cpu) |
| 781 | return false; |
| 782 | /* |
| 783 | * Boot safety: make sure the timekeeping duty has been |
| 784 | * assigned before entering dyntick-idle mode, |
| 785 | */ |
| 786 | if (tick_do_timer_cpu == TICK_DO_TIMER_NONE) |
| 787 | return false; |
| 788 | } |
| 789 | |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 790 | return true; |
| 791 | } |
| 792 | |
Frederic Weisbecker | 19f5f73 | 2011-07-27 17:29:28 +0200 | [diff] [blame] | 793 | static void __tick_nohz_idle_enter(struct tick_sched *ts) |
| 794 | { |
Frederic Weisbecker | 84bf1bc | 2011-08-01 01:25:38 +0200 | [diff] [blame] | 795 | ktime_t now, expires; |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 796 | int cpu = smp_processor_id(); |
Frederic Weisbecker | 19f5f73 | 2011-07-27 17:29:28 +0200 | [diff] [blame] | 797 | |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 798 | now = tick_nohz_start_idle(ts); |
Frederic Weisbecker | 2ac0d98 | 2011-07-28 04:00:47 +0200 | [diff] [blame] | 799 | |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 800 | if (can_stop_idle_tick(cpu, ts)) { |
| 801 | int was_stopped = ts->tick_stopped; |
| 802 | |
| 803 | ts->idle_calls++; |
Frederic Weisbecker | 84bf1bc | 2011-08-01 01:25:38 +0200 | [diff] [blame] | 804 | |
| 805 | expires = tick_nohz_stop_sched_tick(ts, now, cpu); |
| 806 | if (expires.tv64 > 0LL) { |
| 807 | ts->idle_sleeps++; |
| 808 | ts->idle_expires = expires; |
| 809 | } |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 810 | |
| 811 | if (!was_stopped && ts->tick_stopped) |
| 812 | ts->idle_jiffies = ts->last_jiffies; |
| 813 | } |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 814 | } |
| 815 | |
| 816 | /** |
| 817 | * tick_nohz_idle_enter - stop the idle tick from the idle task |
| 818 | * |
| 819 | * When the next event is more than a tick into the future, stop the idle tick |
| 820 | * Called when we start the idle loop. |
Frederic Weisbecker | 2bbb681 | 2011-10-08 16:01:00 +0200 | [diff] [blame] | 821 | * |
Frederic Weisbecker | 1268fbc | 2011-11-17 18:48:14 +0100 | [diff] [blame] | 822 | * The arch is responsible of calling: |
Frederic Weisbecker | 2bbb681 | 2011-10-08 16:01:00 +0200 | [diff] [blame] | 823 | * |
| 824 | * - rcu_idle_enter() after its last use of RCU before the CPU is put |
| 825 | * to sleep. |
| 826 | * - 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] | 827 | */ |
Frederic Weisbecker | 1268fbc | 2011-11-17 18:48:14 +0100 | [diff] [blame] | 828 | void tick_nohz_idle_enter(void) |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 829 | { |
| 830 | struct tick_sched *ts; |
| 831 | |
Frederic Weisbecker | 1268fbc | 2011-11-17 18:48:14 +0100 | [diff] [blame] | 832 | WARN_ON_ONCE(irqs_disabled()); |
| 833 | |
Linus Torvalds | 0db49b7 | 2012-01-06 08:33:28 -0800 | [diff] [blame] | 834 | /* |
| 835 | * Update the idle state in the scheduler domain hierarchy |
| 836 | * when tick_nohz_stop_sched_tick() is called from the idle loop. |
| 837 | * State will be updated to busy during the first busy tick after |
| 838 | * exiting idle. |
| 839 | */ |
| 840 | set_cpu_sd_state_idle(); |
| 841 | |
Frederic Weisbecker | 1268fbc | 2011-11-17 18:48:14 +0100 | [diff] [blame] | 842 | local_irq_disable(); |
| 843 | |
Christoph Lameter | 22127e9 | 2014-08-17 12:30:25 -0500 | [diff] [blame] | 844 | ts = this_cpu_ptr(&tick_cpu_sched); |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 845 | ts->inidle = 1; |
Frederic Weisbecker | 19f5f73 | 2011-07-27 17:29:28 +0200 | [diff] [blame] | 846 | __tick_nohz_idle_enter(ts); |
Frederic Weisbecker | 1268fbc | 2011-11-17 18:48:14 +0100 | [diff] [blame] | 847 | |
| 848 | local_irq_enable(); |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 849 | } |
Jacob Pan | 4dbd277 | 2013-01-04 11:12:43 +0000 | [diff] [blame] | 850 | EXPORT_SYMBOL_GPL(tick_nohz_idle_enter); |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 851 | |
| 852 | /** |
| 853 | * tick_nohz_irq_exit - update next tick event from interrupt exit |
| 854 | * |
| 855 | * When an interrupt fires while we are idle and it doesn't cause |
| 856 | * a reschedule, it may still add, modify or delete a timer, enqueue |
| 857 | * an RCU callback, etc... |
| 858 | * So we need to re-calculate and reprogram the next tick event. |
| 859 | */ |
| 860 | void tick_nohz_irq_exit(void) |
| 861 | { |
Christoph Lameter | 22127e9 | 2014-08-17 12:30:25 -0500 | [diff] [blame] | 862 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 863 | |
Rafael J. Wysocki | 1485191 | 2013-07-27 01:41:34 +0200 | [diff] [blame] | 864 | if (ts->inidle) |
Frederic Weisbecker | 5811d99 | 2013-04-20 16:40:31 +0200 | [diff] [blame] | 865 | __tick_nohz_idle_enter(ts); |
Rafael J. Wysocki | 1485191 | 2013-07-27 01:41:34 +0200 | [diff] [blame] | 866 | else |
Frederic Weisbecker | 5811d99 | 2013-04-20 16:40:31 +0200 | [diff] [blame] | 867 | tick_nohz_full_stop_tick(ts); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 868 | } |
| 869 | |
| 870 | /** |
Len Brown | 4f86d3a | 2007-10-03 18:58:00 -0400 | [diff] [blame] | 871 | * tick_nohz_get_sleep_length - return the length of the current sleep |
| 872 | * |
| 873 | * Called from power state control code with interrupts disabled |
| 874 | */ |
| 875 | ktime_t tick_nohz_get_sleep_length(void) |
| 876 | { |
Christoph Lameter | 22127e9 | 2014-08-17 12:30:25 -0500 | [diff] [blame] | 877 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
Len Brown | 4f86d3a | 2007-10-03 18:58:00 -0400 | [diff] [blame] | 878 | |
| 879 | return ts->sleep_length; |
| 880 | } |
| 881 | |
Thomas Gleixner | c34bec5 | 2008-10-17 10:04:34 +0200 | [diff] [blame] | 882 | static void tick_nohz_restart(struct tick_sched *ts, ktime_t now) |
| 883 | { |
| 884 | hrtimer_cancel(&ts->sched_timer); |
Frederic Weisbecker | f5d411c | 2011-07-31 17:44:12 +0200 | [diff] [blame] | 885 | hrtimer_set_expires(&ts->sched_timer, ts->last_tick); |
Thomas Gleixner | c34bec5 | 2008-10-17 10:04:34 +0200 | [diff] [blame] | 886 | |
| 887 | while (1) { |
| 888 | /* Forward the time to expire in the future */ |
| 889 | hrtimer_forward(&ts->sched_timer, now, tick_period); |
| 890 | |
| 891 | if (ts->nohz_mode == NOHZ_MODE_HIGHRES) { |
Thomas Gleixner | 268a3dc | 2008-10-22 09:48:06 +0200 | [diff] [blame] | 892 | hrtimer_start_expires(&ts->sched_timer, |
Arun R Bharadwaj | 5c33386 | 2009-04-16 12:14:37 +0530 | [diff] [blame] | 893 | HRTIMER_MODE_ABS_PINNED); |
Thomas Gleixner | c34bec5 | 2008-10-17 10:04:34 +0200 | [diff] [blame] | 894 | /* Check, if the timer was already in the past */ |
| 895 | if (hrtimer_active(&ts->sched_timer)) |
| 896 | break; |
| 897 | } else { |
Thomas Gleixner | 268a3dc | 2008-10-22 09:48:06 +0200 | [diff] [blame] | 898 | if (!tick_program_event( |
| 899 | hrtimer_get_expires(&ts->sched_timer), 0)) |
Thomas Gleixner | c34bec5 | 2008-10-17 10:04:34 +0200 | [diff] [blame] | 900 | break; |
| 901 | } |
Neal Cardwell | 6f10392 | 2012-03-27 15:09:37 -0400 | [diff] [blame] | 902 | /* Reread time and update jiffies */ |
Thomas Gleixner | c34bec5 | 2008-10-17 10:04:34 +0200 | [diff] [blame] | 903 | now = ktime_get(); |
Neal Cardwell | 6f10392 | 2012-03-27 15:09:37 -0400 | [diff] [blame] | 904 | tick_do_update_jiffies64(now); |
Thomas Gleixner | c34bec5 | 2008-10-17 10:04:34 +0200 | [diff] [blame] | 905 | } |
| 906 | } |
| 907 | |
Frederic Weisbecker | 19f5f73 | 2011-07-27 17:29:28 +0200 | [diff] [blame] | 908 | 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] | 909 | { |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 910 | /* Update jiffies first */ |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 911 | tick_do_update_jiffies64(now); |
Peter Zijlstra | 5aaa0b7 | 2012-05-17 17:15:29 +0200 | [diff] [blame] | 912 | update_cpu_load_nohz(); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 913 | |
Charles Wang | 749c881 | 2012-08-20 16:02:33 +0800 | [diff] [blame] | 914 | calc_load_exit_idle(); |
Frederic Weisbecker | 2ac0d98 | 2011-07-28 04:00:47 +0200 | [diff] [blame] | 915 | touch_softlockup_watchdog(); |
| 916 | /* |
| 917 | * Cancel the scheduled timer and restore the tick |
| 918 | */ |
| 919 | ts->tick_stopped = 0; |
| 920 | ts->idle_exittime = now; |
| 921 | |
| 922 | tick_nohz_restart(ts, now); |
| 923 | } |
| 924 | |
| 925 | static void tick_nohz_account_idle_ticks(struct tick_sched *ts) |
| 926 | { |
Frederic Weisbecker | 3f4724e | 2012-07-16 18:00:34 +0200 | [diff] [blame] | 927 | #ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE |
Frederic Weisbecker | 2ac0d98 | 2011-07-28 04:00:47 +0200 | [diff] [blame] | 928 | unsigned long ticks; |
Frederic Weisbecker | 3f4724e | 2012-07-16 18:00:34 +0200 | [diff] [blame] | 929 | |
| 930 | if (vtime_accounting_enabled()) |
| 931 | return; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 932 | /* |
| 933 | * We stopped the tick in idle. Update process times would miss the |
| 934 | * time we slept as update_process_times does only a 1 tick |
| 935 | * accounting. Enforce that this is accounted to idle ! |
| 936 | */ |
| 937 | ticks = jiffies - ts->idle_jiffies; |
| 938 | /* |
| 939 | * We might be one off. Do not randomly account a huge number of ticks! |
| 940 | */ |
Martin Schwidefsky | 79741dd | 2008-12-31 15:11:38 +0100 | [diff] [blame] | 941 | if (ticks && ticks < LONG_MAX) |
| 942 | account_idle_ticks(ticks); |
| 943 | #endif |
Frederic Weisbecker | 19f5f73 | 2011-07-27 17:29:28 +0200 | [diff] [blame] | 944 | } |
| 945 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 946 | /** |
| 947 | * tick_nohz_idle_exit - restart the idle tick from the idle task |
| 948 | * |
| 949 | * Restart the idle tick when the CPU is woken up from idle |
| 950 | * This also exit the RCU extended quiescent state. The CPU |
| 951 | * can use RCU again after this function is called. |
| 952 | */ |
| 953 | void tick_nohz_idle_exit(void) |
| 954 | { |
Christoph Lameter | 4a32fea | 2014-08-17 12:30:27 -0500 | [diff] [blame] | 955 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 956 | ktime_t now; |
| 957 | |
| 958 | local_irq_disable(); |
| 959 | |
| 960 | WARN_ON_ONCE(!ts->inidle); |
| 961 | |
| 962 | ts->inidle = 0; |
| 963 | |
| 964 | if (ts->idle_active || ts->tick_stopped) |
| 965 | now = ktime_get(); |
| 966 | |
| 967 | if (ts->idle_active) |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 968 | tick_nohz_stop_idle(ts, now); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 969 | |
Frederic Weisbecker | 2ac0d98 | 2011-07-28 04:00:47 +0200 | [diff] [blame] | 970 | if (ts->tick_stopped) { |
Frederic Weisbecker | 19f5f73 | 2011-07-27 17:29:28 +0200 | [diff] [blame] | 971 | tick_nohz_restart_sched_tick(ts, now); |
Frederic Weisbecker | 2ac0d98 | 2011-07-28 04:00:47 +0200 | [diff] [blame] | 972 | tick_nohz_account_idle_ticks(ts); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 973 | } |
| 974 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 975 | local_irq_enable(); |
| 976 | } |
Jacob Pan | 4dbd277 | 2013-01-04 11:12:43 +0000 | [diff] [blame] | 977 | EXPORT_SYMBOL_GPL(tick_nohz_idle_exit); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 978 | |
| 979 | static int tick_nohz_reprogram(struct tick_sched *ts, ktime_t now) |
| 980 | { |
| 981 | hrtimer_forward(&ts->sched_timer, now, tick_period); |
Arjan van de Ven | cc584b2 | 2008-09-01 15:02:30 -0700 | [diff] [blame] | 982 | return tick_program_event(hrtimer_get_expires(&ts->sched_timer), 0); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 983 | } |
| 984 | |
| 985 | /* |
| 986 | * The nohz low res interrupt handler |
| 987 | */ |
| 988 | static void tick_nohz_handler(struct clock_event_device *dev) |
| 989 | { |
Christoph Lameter | 22127e9 | 2014-08-17 12:30:25 -0500 | [diff] [blame] | 990 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 991 | struct pt_regs *regs = get_irq_regs(); |
| 992 | ktime_t now = ktime_get(); |
| 993 | |
| 994 | dev->next_event.tv64 = KTIME_MAX; |
| 995 | |
Frederic Weisbecker | 5bb9622 | 2012-10-15 02:03:27 +0200 | [diff] [blame] | 996 | tick_sched_do_timer(now); |
Frederic Weisbecker | 9e8f559 | 2012-10-15 02:43:03 +0200 | [diff] [blame] | 997 | tick_sched_handle(ts, regs); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 998 | |
Viresh Kumar | b5e995e | 2014-06-12 16:24:41 +0530 | [diff] [blame] | 999 | /* No need to reprogram if we are running tickless */ |
| 1000 | if (unlikely(ts->tick_stopped)) |
| 1001 | return; |
| 1002 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1003 | while (tick_nohz_reprogram(ts, now)) { |
| 1004 | now = ktime_get(); |
| 1005 | tick_do_update_jiffies64(now); |
| 1006 | } |
| 1007 | } |
| 1008 | |
| 1009 | /** |
| 1010 | * tick_nohz_switch_to_nohz - switch to nohz mode |
| 1011 | */ |
| 1012 | static void tick_nohz_switch_to_nohz(void) |
| 1013 | { |
Christoph Lameter | 22127e9 | 2014-08-17 12:30:25 -0500 | [diff] [blame] | 1014 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1015 | ktime_t next; |
| 1016 | |
Viresh Kumar | 2763053 | 2014-04-15 10:54:41 +0530 | [diff] [blame] | 1017 | if (!tick_nohz_enabled) |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1018 | return; |
| 1019 | |
| 1020 | local_irq_disable(); |
| 1021 | if (tick_switch_to_oneshot(tick_nohz_handler)) { |
| 1022 | local_irq_enable(); |
| 1023 | return; |
| 1024 | } |
Thomas Gleixner | d689fe2 | 2013-11-13 21:01:57 +0100 | [diff] [blame] | 1025 | tick_nohz_active = 1; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1026 | ts->nohz_mode = NOHZ_MODE_LOWRES; |
| 1027 | |
| 1028 | /* |
| 1029 | * Recycle the hrtimer in ts, so we can share the |
| 1030 | * hrtimer_forward with the highres code. |
| 1031 | */ |
| 1032 | hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); |
| 1033 | /* Get the next period */ |
| 1034 | next = tick_init_jiffy_update(); |
| 1035 | |
| 1036 | for (;;) { |
Arjan van de Ven | cc584b2 | 2008-09-01 15:02:30 -0700 | [diff] [blame] | 1037 | hrtimer_set_expires(&ts->sched_timer, next); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1038 | if (!tick_program_event(next, 0)) |
| 1039 | break; |
| 1040 | next = ktime_add(next, tick_period); |
| 1041 | } |
| 1042 | local_irq_enable(); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1043 | } |
| 1044 | |
Thomas Gleixner | fb02fbc | 2008-10-17 10:01:23 +0200 | [diff] [blame] | 1045 | /* |
| 1046 | * When NOHZ is enabled and the tick is stopped, we need to kick the |
| 1047 | * tick timer from irq_enter() so that the jiffies update is kept |
| 1048 | * alive during long running softirqs. That's ugly as hell, but |
| 1049 | * correctness is key even if we need to fix the offending softirq in |
| 1050 | * the first place. |
| 1051 | * |
| 1052 | * Note, this is different to tick_nohz_restart. We just kick the |
| 1053 | * timer and do not touch the other magic bits which need to be done |
| 1054 | * when idle is left. |
| 1055 | */ |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 1056 | static void tick_nohz_kick_tick(struct tick_sched *ts, ktime_t now) |
Thomas Gleixner | fb02fbc | 2008-10-17 10:01:23 +0200 | [diff] [blame] | 1057 | { |
Thomas Gleixner | ae99286 | 2008-11-10 13:20:23 +0100 | [diff] [blame] | 1058 | #if 0 |
| 1059 | /* Switch back to 2.6.27 behaviour */ |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 1060 | ktime_t delta; |
Thomas Gleixner | fb02fbc | 2008-10-17 10:01:23 +0200 | [diff] [blame] | 1061 | |
Thomas Gleixner | c4bd822 | 2008-10-21 20:17:35 +0200 | [diff] [blame] | 1062 | /* |
| 1063 | * Do not touch the tick device, when the next expiry is either |
| 1064 | * already reached or less/equal than the tick period. |
| 1065 | */ |
Thomas Gleixner | 268a3dc | 2008-10-22 09:48:06 +0200 | [diff] [blame] | 1066 | delta = ktime_sub(hrtimer_get_expires(&ts->sched_timer), now); |
Thomas Gleixner | c4bd822 | 2008-10-21 20:17:35 +0200 | [diff] [blame] | 1067 | if (delta.tv64 <= tick_period.tv64) |
| 1068 | return; |
| 1069 | |
| 1070 | tick_nohz_restart(ts, now); |
Thomas Gleixner | ae99286 | 2008-11-10 13:20:23 +0100 | [diff] [blame] | 1071 | #endif |
Thomas Gleixner | fb02fbc | 2008-10-17 10:01:23 +0200 | [diff] [blame] | 1072 | } |
| 1073 | |
Frederic Weisbecker | 5acac1b | 2013-12-04 18:28:20 +0100 | [diff] [blame] | 1074 | static inline void tick_nohz_irq_enter(void) |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 1075 | { |
Christoph Lameter | 4a32fea | 2014-08-17 12:30:27 -0500 | [diff] [blame] | 1076 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 1077 | ktime_t now; |
| 1078 | |
| 1079 | if (!ts->idle_active && !ts->tick_stopped) |
| 1080 | return; |
| 1081 | now = ktime_get(); |
| 1082 | if (ts->idle_active) |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 1083 | tick_nohz_stop_idle(ts, now); |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 1084 | if (ts->tick_stopped) { |
| 1085 | tick_nohz_update_jiffies(now); |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 1086 | tick_nohz_kick_tick(ts, now); |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 1087 | } |
| 1088 | } |
| 1089 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1090 | #else |
| 1091 | |
| 1092 | static inline void tick_nohz_switch_to_nohz(void) { } |
Frederic Weisbecker | 5acac1b | 2013-12-04 18:28:20 +0100 | [diff] [blame] | 1093 | static inline void tick_nohz_irq_enter(void) { } |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1094 | |
Frederic Weisbecker | 3451d02 | 2011-08-10 23:21:01 +0200 | [diff] [blame] | 1095 | #endif /* CONFIG_NO_HZ_COMMON */ |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1096 | |
| 1097 | /* |
Thomas Gleixner | 719254f | 2008-10-17 09:59:47 +0200 | [diff] [blame] | 1098 | * Called from irq_enter to notify about the possible interruption of idle() |
| 1099 | */ |
Frederic Weisbecker | 5acac1b | 2013-12-04 18:28:20 +0100 | [diff] [blame] | 1100 | void tick_irq_enter(void) |
Thomas Gleixner | 719254f | 2008-10-17 09:59:47 +0200 | [diff] [blame] | 1101 | { |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 1102 | tick_check_oneshot_broadcast_this_cpu(); |
Frederic Weisbecker | 5acac1b | 2013-12-04 18:28:20 +0100 | [diff] [blame] | 1103 | tick_nohz_irq_enter(); |
Thomas Gleixner | 719254f | 2008-10-17 09:59:47 +0200 | [diff] [blame] | 1104 | } |
| 1105 | |
| 1106 | /* |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1107 | * High resolution timer specific code |
| 1108 | */ |
| 1109 | #ifdef CONFIG_HIGH_RES_TIMERS |
| 1110 | /* |
Pavel Machek | 4c9dc64 | 2008-01-30 13:30:00 +0100 | [diff] [blame] | 1111 | * We rearm the timer until we get disabled by the idle code. |
Chuansheng Liu | 351f181 | 2012-10-25 01:07:35 +0800 | [diff] [blame] | 1112 | * Called with interrupts disabled. |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1113 | */ |
| 1114 | static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer) |
| 1115 | { |
| 1116 | struct tick_sched *ts = |
| 1117 | container_of(timer, struct tick_sched, sched_timer); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1118 | struct pt_regs *regs = get_irq_regs(); |
| 1119 | ktime_t now = ktime_get(); |
Thomas Gleixner | d3ed782 | 2007-05-08 00:30:03 -0700 | [diff] [blame] | 1120 | |
Frederic Weisbecker | 5bb9622 | 2012-10-15 02:03:27 +0200 | [diff] [blame] | 1121 | tick_sched_do_timer(now); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1122 | |
| 1123 | /* |
| 1124 | * Do not call, when we are not in irq context and have |
| 1125 | * no valid regs pointer |
| 1126 | */ |
Frederic Weisbecker | 9e8f559 | 2012-10-15 02:43:03 +0200 | [diff] [blame] | 1127 | if (regs) |
| 1128 | tick_sched_handle(ts, regs); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1129 | |
Viresh Kumar | 2a16fc9 | 2014-06-12 16:24:41 +0530 | [diff] [blame] | 1130 | /* No need to reprogram if we are in idle or full dynticks mode */ |
| 1131 | if (unlikely(ts->tick_stopped)) |
| 1132 | return HRTIMER_NORESTART; |
| 1133 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1134 | hrtimer_forward(timer, now, tick_period); |
| 1135 | |
| 1136 | return HRTIMER_RESTART; |
| 1137 | } |
| 1138 | |
Mike Galbraith | 5307c95 | 2012-05-08 12:20:58 +0200 | [diff] [blame] | 1139 | static int sched_skew_tick; |
| 1140 | |
Thomas Gleixner | 62cf20b | 2012-05-25 14:08:57 +0200 | [diff] [blame] | 1141 | static int __init skew_tick(char *str) |
| 1142 | { |
| 1143 | get_option(&str, &sched_skew_tick); |
| 1144 | |
| 1145 | return 0; |
| 1146 | } |
| 1147 | early_param("skew_tick", skew_tick); |
| 1148 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1149 | /** |
| 1150 | * tick_setup_sched_timer - setup the tick emulation timer |
| 1151 | */ |
| 1152 | void tick_setup_sched_timer(void) |
| 1153 | { |
Christoph Lameter | 22127e9 | 2014-08-17 12:30:25 -0500 | [diff] [blame] | 1154 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1155 | ktime_t now = ktime_get(); |
| 1156 | |
| 1157 | /* |
| 1158 | * Emulate tick processing via per-CPU hrtimers: |
| 1159 | */ |
| 1160 | hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); |
| 1161 | ts->sched_timer.function = tick_sched_timer; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1162 | |
john stultz | 3704540 | 2007-07-21 04:37:35 -0700 | [diff] [blame] | 1163 | /* Get the next period (per cpu) */ |
Arjan van de Ven | cc584b2 | 2008-09-01 15:02:30 -0700 | [diff] [blame] | 1164 | hrtimer_set_expires(&ts->sched_timer, tick_init_jiffy_update()); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1165 | |
Thomas Gleixner | 9c3f9e2 | 2012-11-21 20:31:52 +0100 | [diff] [blame] | 1166 | /* Offset the tick to avert jiffies_lock contention. */ |
Mike Galbraith | 5307c95 | 2012-05-08 12:20:58 +0200 | [diff] [blame] | 1167 | if (sched_skew_tick) { |
| 1168 | u64 offset = ktime_to_ns(tick_period) >> 1; |
| 1169 | do_div(offset, num_possible_cpus()); |
| 1170 | offset *= smp_processor_id(); |
| 1171 | hrtimer_add_expires_ns(&ts->sched_timer, offset); |
| 1172 | } |
| 1173 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1174 | for (;;) { |
| 1175 | hrtimer_forward(&ts->sched_timer, now, tick_period); |
Arun R Bharadwaj | 5c33386 | 2009-04-16 12:14:37 +0530 | [diff] [blame] | 1176 | hrtimer_start_expires(&ts->sched_timer, |
| 1177 | HRTIMER_MODE_ABS_PINNED); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1178 | /* Check, if the timer was already in the past */ |
| 1179 | if (hrtimer_active(&ts->sched_timer)) |
| 1180 | break; |
| 1181 | now = ktime_get(); |
| 1182 | } |
| 1183 | |
Frederic Weisbecker | 3451d02 | 2011-08-10 23:21:01 +0200 | [diff] [blame] | 1184 | #ifdef CONFIG_NO_HZ_COMMON |
Thomas Gleixner | d689fe2 | 2013-11-13 21:01:57 +0100 | [diff] [blame] | 1185 | if (tick_nohz_enabled) { |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1186 | ts->nohz_mode = NOHZ_MODE_HIGHRES; |
Thomas Gleixner | d689fe2 | 2013-11-13 21:01:57 +0100 | [diff] [blame] | 1187 | tick_nohz_active = 1; |
| 1188 | } |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1189 | #endif |
| 1190 | } |
Miao Xie | 3c4fbe5 | 2008-08-20 16:37:38 -0700 | [diff] [blame] | 1191 | #endif /* HIGH_RES_TIMERS */ |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1192 | |
Frederic Weisbecker | 3451d02 | 2011-08-10 23:21:01 +0200 | [diff] [blame] | 1193 | #if defined CONFIG_NO_HZ_COMMON || defined CONFIG_HIGH_RES_TIMERS |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1194 | void tick_cancel_sched_timer(int cpu) |
| 1195 | { |
| 1196 | struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); |
| 1197 | |
Miao Xie | 3c4fbe5 | 2008-08-20 16:37:38 -0700 | [diff] [blame] | 1198 | # ifdef CONFIG_HIGH_RES_TIMERS |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1199 | if (ts->sched_timer.base) |
| 1200 | hrtimer_cancel(&ts->sched_timer); |
Miao Xie | 3c4fbe5 | 2008-08-20 16:37:38 -0700 | [diff] [blame] | 1201 | # endif |
Karsten Wiese | a790176 | 2008-03-04 14:59:55 -0800 | [diff] [blame] | 1202 | |
Thomas Gleixner | 4b0c0f2 | 2013-05-03 15:02:50 +0200 | [diff] [blame] | 1203 | memset(ts, 0, sizeof(*ts)); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1204 | } |
Miao Xie | 3c4fbe5 | 2008-08-20 16:37:38 -0700 | [diff] [blame] | 1205 | #endif |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1206 | |
| 1207 | /** |
| 1208 | * Async notification about clocksource changes |
| 1209 | */ |
| 1210 | void tick_clock_notify(void) |
| 1211 | { |
| 1212 | int cpu; |
| 1213 | |
| 1214 | for_each_possible_cpu(cpu) |
| 1215 | set_bit(0, &per_cpu(tick_cpu_sched, cpu).check_clocks); |
| 1216 | } |
| 1217 | |
| 1218 | /* |
| 1219 | * Async notification about clock event changes |
| 1220 | */ |
| 1221 | void tick_oneshot_notify(void) |
| 1222 | { |
Christoph Lameter | 22127e9 | 2014-08-17 12:30:25 -0500 | [diff] [blame] | 1223 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1224 | |
| 1225 | set_bit(0, &ts->check_clocks); |
| 1226 | } |
| 1227 | |
| 1228 | /** |
| 1229 | * Check, if a change happened, which makes oneshot possible. |
| 1230 | * |
| 1231 | * Called cyclic from the hrtimer softirq (driven by the timer |
| 1232 | * softirq) allow_nohz signals, that we can switch into low-res nohz |
| 1233 | * mode, because high resolution timers are disabled (either compile |
| 1234 | * or runtime). |
| 1235 | */ |
| 1236 | int tick_check_oneshot_change(int allow_nohz) |
| 1237 | { |
Christoph Lameter | 22127e9 | 2014-08-17 12:30:25 -0500 | [diff] [blame] | 1238 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1239 | |
| 1240 | if (!test_and_clear_bit(0, &ts->check_clocks)) |
| 1241 | return 0; |
| 1242 | |
| 1243 | if (ts->nohz_mode != NOHZ_MODE_INACTIVE) |
| 1244 | return 0; |
| 1245 | |
Li Zefan | cf4fc6c | 2008-02-08 04:19:24 -0800 | [diff] [blame] | 1246 | if (!timekeeping_valid_for_hres() || !tick_is_oneshot_available()) |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1247 | return 0; |
| 1248 | |
| 1249 | if (!allow_nohz) |
| 1250 | return 1; |
| 1251 | |
| 1252 | tick_nohz_switch_to_nohz(); |
| 1253 | return 0; |
| 1254 | } |