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 | 460775df | 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 | { |
Frederic Weisbecker | 9014c45 | 2013-04-20 15:43:57 +0200 | [diff] [blame] | 208 | struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched); |
| 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 | |
| 238 | irq_work_queue(&__get_cpu_var(nohz_full_kick_work)); |
| 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 | |
| 368 | cpu = smp_processor_id(); |
| 369 | |
| 370 | if (cpumask_test_cpu(cpu, tick_nohz_full_mask)) { |
| 371 | pr_warning("NO_HZ: Clearing %d from nohz_full range for timekeeping\n", cpu); |
| 372 | cpumask_clear_cpu(cpu, tick_nohz_full_mask); |
| 373 | } |
| 374 | |
| 375 | cpumask_andnot(housekeeping_mask, |
| 376 | cpu_possible_mask, tick_nohz_full_mask); |
| 377 | |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 378 | for_each_cpu(cpu, tick_nohz_full_mask) |
Frederic Weisbecker | 2e70933 | 2013-07-10 00:55:25 +0200 | [diff] [blame] | 379 | context_tracking_cpu_set(cpu); |
| 380 | |
Frederic Weisbecker | d1e43fa | 2013-03-26 23:47:24 +0100 | [diff] [blame] | 381 | cpu_notifier(tick_nohz_cpu_down_callback, 0); |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 382 | 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] | 383 | pr_info("NO_HZ: Full dynticks CPUs: %s.\n", nohz_full_buf); |
Frederic Weisbecker | a831881 | 2012-12-18 17:32:19 +0100 | [diff] [blame] | 384 | } |
Frederic Weisbecker | a831881 | 2012-12-18 17:32:19 +0100 | [diff] [blame] | 385 | #endif |
| 386 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 387 | /* |
| 388 | * NOHZ - aka dynamic tick functionality |
| 389 | */ |
Frederic Weisbecker | 3451d02 | 2011-08-10 23:21:01 +0200 | [diff] [blame] | 390 | #ifdef CONFIG_NO_HZ_COMMON |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 391 | /* |
| 392 | * NO HZ enabled ? |
| 393 | */ |
Thomas Gleixner | d689fe2 | 2013-11-13 21:01:57 +0100 | [diff] [blame] | 394 | static int tick_nohz_enabled __read_mostly = 1; |
| 395 | int tick_nohz_active __read_mostly; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 396 | /* |
| 397 | * Enable / Disable tickless mode |
| 398 | */ |
| 399 | static int __init setup_tick_nohz(char *str) |
| 400 | { |
| 401 | if (!strcmp(str, "off")) |
| 402 | tick_nohz_enabled = 0; |
| 403 | else if (!strcmp(str, "on")) |
| 404 | tick_nohz_enabled = 1; |
| 405 | else |
| 406 | return 0; |
| 407 | return 1; |
| 408 | } |
| 409 | |
| 410 | __setup("nohz=", setup_tick_nohz); |
| 411 | |
| 412 | /** |
| 413 | * tick_nohz_update_jiffies - update jiffies when idle was interrupted |
| 414 | * |
| 415 | * Called from interrupt entry when the CPU was idle |
| 416 | * |
| 417 | * In case the sched_tick was stopped on this CPU, we have to check if jiffies |
| 418 | * must be updated. Otherwise an interrupt handler could use a stale jiffy |
| 419 | * value. We do this unconditionally on any cpu, as we don't know whether the |
| 420 | * cpu, which has the update task assigned is in a long sleep. |
| 421 | */ |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 422 | static void tick_nohz_update_jiffies(ktime_t now) |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 423 | { |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 424 | unsigned long flags; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 425 | |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 426 | __this_cpu_write(tick_cpu_sched.idle_waketime, now); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 427 | |
| 428 | local_irq_save(flags); |
| 429 | tick_do_update_jiffies64(now); |
| 430 | local_irq_restore(flags); |
Ingo Molnar | 02ff375 | 2008-05-12 15:43:53 +0200 | [diff] [blame] | 431 | |
| 432 | touch_softlockup_watchdog(); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 433 | } |
| 434 | |
Arjan van de Ven | 595aac4 | 2010-05-09 08:22:45 -0700 | [diff] [blame] | 435 | /* |
| 436 | * Updates the per cpu time idle statistics counters |
| 437 | */ |
Arjan van de Ven | 8d63bf9 | 2010-05-09 08:24:03 -0700 | [diff] [blame] | 438 | static void |
Peter Zijlstra | 8c215bd | 2010-07-01 09:07:17 +0200 | [diff] [blame] | 439 | 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] | 440 | { |
| 441 | ktime_t delta; |
| 442 | |
Arjan van de Ven | 595aac4 | 2010-05-09 08:22:45 -0700 | [diff] [blame] | 443 | if (ts->idle_active) { |
| 444 | delta = ktime_sub(now, ts->idle_entrytime); |
Peter Zijlstra | 8c215bd | 2010-07-01 09:07:17 +0200 | [diff] [blame] | 445 | if (nr_iowait_cpu(cpu) > 0) |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 446 | ts->iowait_sleeptime = ktime_add(ts->iowait_sleeptime, delta); |
Michal Hocko | 6beea0c | 2011-08-24 09:37:48 +0200 | [diff] [blame] | 447 | else |
| 448 | ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta); |
Arjan van de Ven | 8c7b09f | 2010-05-09 08:23:23 -0700 | [diff] [blame] | 449 | ts->idle_entrytime = now; |
Arjan van de Ven | 595aac4 | 2010-05-09 08:22:45 -0700 | [diff] [blame] | 450 | } |
Arjan van de Ven | 8d63bf9 | 2010-05-09 08:24:03 -0700 | [diff] [blame] | 451 | |
Arjan van de Ven | e0e37c2 | 2010-05-09 08:24:39 -0700 | [diff] [blame] | 452 | if (last_update_time) |
Arjan van de Ven | 8d63bf9 | 2010-05-09 08:24:03 -0700 | [diff] [blame] | 453 | *last_update_time = ktime_to_us(now); |
| 454 | |
Arjan van de Ven | 595aac4 | 2010-05-09 08:22:45 -0700 | [diff] [blame] | 455 | } |
| 456 | |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 457 | 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] | 458 | { |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 459 | update_ts_time_stats(smp_processor_id(), ts, now, NULL); |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 460 | ts->idle_active = 0; |
Peter Zijlstra | 56c7426 | 2008-09-01 16:44:23 +0200 | [diff] [blame] | 461 | |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 462 | sched_clock_idle_wakeup_event(0); |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 463 | } |
| 464 | |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 465 | static ktime_t tick_nohz_start_idle(struct tick_sched *ts) |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 466 | { |
Michal Hocko | 430ee88 | 2011-12-01 17:00:22 +0100 | [diff] [blame] | 467 | ktime_t now = ktime_get(); |
Arjan van de Ven | 595aac4 | 2010-05-09 08:22:45 -0700 | [diff] [blame] | 468 | |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 469 | ts->idle_entrytime = now; |
| 470 | ts->idle_active = 1; |
Peter Zijlstra | 56c7426 | 2008-09-01 16:44:23 +0200 | [diff] [blame] | 471 | sched_clock_idle_sleep_event(); |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 472 | return now; |
| 473 | } |
| 474 | |
Arjan van de Ven | b1f724c | 2010-05-09 08:22:08 -0700 | [diff] [blame] | 475 | /** |
| 476 | * get_cpu_idle_time_us - get the total idle time of a cpu |
| 477 | * @cpu: CPU number to query |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 478 | * @last_update_time: variable to store update time in. Do not update |
| 479 | * counters if NULL. |
Arjan van de Ven | b1f724c | 2010-05-09 08:22:08 -0700 | [diff] [blame] | 480 | * |
| 481 | * Return the cummulative idle time (since boot) for a given |
Michal Hocko | 6beea0c | 2011-08-24 09:37:48 +0200 | [diff] [blame] | 482 | * CPU, in microseconds. |
Arjan van de Ven | b1f724c | 2010-05-09 08:22:08 -0700 | [diff] [blame] | 483 | * |
| 484 | * This time is measured via accounting rather than sampling, |
| 485 | * and is as accurate as ktime_get() is. |
| 486 | * |
| 487 | * This function returns -1 if NOHZ is not enabled. |
| 488 | */ |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 489 | u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time) |
| 490 | { |
| 491 | struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 492 | ktime_t now, idle; |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 493 | |
Thomas Gleixner | d689fe2 | 2013-11-13 21:01:57 +0100 | [diff] [blame] | 494 | if (!tick_nohz_active) |
venkatesh.pallipadi@intel.com | 8083e4a | 2008-08-04 11:59:11 -0700 | [diff] [blame] | 495 | return -1; |
| 496 | |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 497 | now = ktime_get(); |
| 498 | if (last_update_time) { |
| 499 | update_ts_time_stats(cpu, ts, now, last_update_time); |
| 500 | idle = ts->idle_sleeptime; |
| 501 | } else { |
| 502 | if (ts->idle_active && !nr_iowait_cpu(cpu)) { |
| 503 | ktime_t delta = ktime_sub(now, ts->idle_entrytime); |
venkatesh.pallipadi@intel.com | 8083e4a | 2008-08-04 11:59:11 -0700 | [diff] [blame] | 504 | |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 505 | idle = ktime_add(ts->idle_sleeptime, delta); |
| 506 | } else { |
| 507 | idle = ts->idle_sleeptime; |
| 508 | } |
| 509 | } |
| 510 | |
| 511 | return ktime_to_us(idle); |
| 512 | |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 513 | } |
venkatesh.pallipadi@intel.com | 8083e4a | 2008-08-04 11:59:11 -0700 | [diff] [blame] | 514 | EXPORT_SYMBOL_GPL(get_cpu_idle_time_us); |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 515 | |
Michal Hocko | 6beea0c | 2011-08-24 09:37:48 +0200 | [diff] [blame] | 516 | /** |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 517 | * get_cpu_iowait_time_us - get the total iowait time of a cpu |
| 518 | * @cpu: CPU number to query |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 519 | * @last_update_time: variable to store update time in. Do not update |
| 520 | * counters if NULL. |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 521 | * |
| 522 | * Return the cummulative iowait time (since boot) for a given |
| 523 | * CPU, in microseconds. |
| 524 | * |
| 525 | * This time is measured via accounting rather than sampling, |
| 526 | * and is as accurate as ktime_get() is. |
| 527 | * |
| 528 | * This function returns -1 if NOHZ is not enabled. |
| 529 | */ |
| 530 | u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time) |
| 531 | { |
| 532 | struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 533 | ktime_t now, iowait; |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 534 | |
Thomas Gleixner | d689fe2 | 2013-11-13 21:01:57 +0100 | [diff] [blame] | 535 | if (!tick_nohz_active) |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 536 | return -1; |
| 537 | |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 538 | now = ktime_get(); |
| 539 | if (last_update_time) { |
| 540 | update_ts_time_stats(cpu, ts, now, last_update_time); |
| 541 | iowait = ts->iowait_sleeptime; |
| 542 | } else { |
| 543 | if (ts->idle_active && nr_iowait_cpu(cpu) > 0) { |
| 544 | ktime_t delta = ktime_sub(now, ts->idle_entrytime); |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 545 | |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 546 | iowait = ktime_add(ts->iowait_sleeptime, delta); |
| 547 | } else { |
| 548 | iowait = ts->iowait_sleeptime; |
| 549 | } |
| 550 | } |
| 551 | |
| 552 | return ktime_to_us(iowait); |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 553 | } |
| 554 | EXPORT_SYMBOL_GPL(get_cpu_iowait_time_us); |
| 555 | |
Frederic Weisbecker | 84bf1bc | 2011-08-01 01:25:38 +0200 | [diff] [blame] | 556 | static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts, |
| 557 | ktime_t now, int cpu) |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 558 | { |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 559 | unsigned long seq, last_jiffies, next_jiffies, delta_jiffies; |
Frederic Weisbecker | 84bf1bc | 2011-08-01 01:25:38 +0200 | [diff] [blame] | 560 | ktime_t last_update, expires, ret = { .tv64 = 0 }; |
Paul E. McKenney | aa9b1630 | 2012-05-10 16:41:44 -0700 | [diff] [blame] | 561 | unsigned long rcu_delta_jiffies; |
Len Brown | 4f86d3a | 2007-10-03 18:58:00 -0400 | [diff] [blame] | 562 | struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev; |
Jon Hunter | 9896246 | 2009-08-18 12:45:10 -0500 | [diff] [blame] | 563 | u64 time_delta; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 564 | |
Frederic Weisbecker | 855a0fc | 2013-12-17 00:16:37 +0100 | [diff] [blame] | 565 | time_delta = timekeeping_max_deferment(); |
| 566 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 567 | /* Read jiffies and the time when jiffies were updated last */ |
| 568 | do { |
John Stultz | d6ad418 | 2012-02-28 16:50:11 -0800 | [diff] [blame] | 569 | seq = read_seqbegin(&jiffies_lock); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 570 | last_update = last_jiffies_update; |
| 571 | last_jiffies = jiffies; |
John Stultz | d6ad418 | 2012-02-28 16:50:11 -0800 | [diff] [blame] | 572 | } while (read_seqretry(&jiffies_lock, seq)); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 573 | |
Frederic Weisbecker | 74876a9 | 2012-10-12 18:00:23 +0200 | [diff] [blame] | 574 | if (rcu_needs_cpu(cpu, &rcu_delta_jiffies) || |
Frederic Weisbecker | 00b4295 | 2012-11-07 21:03:07 +0100 | [diff] [blame] | 575 | arch_needs_cpu(cpu) || irq_work_needs_cpu()) { |
Martin Schwidefsky | 3c5d92a | 2009-09-29 14:25:16 +0200 | [diff] [blame] | 576 | next_jiffies = last_jiffies + 1; |
Ingo Molnar | 6ba9b34 | 2007-02-19 18:11:56 +0000 | [diff] [blame] | 577 | delta_jiffies = 1; |
Martin Schwidefsky | 3c5d92a | 2009-09-29 14:25:16 +0200 | [diff] [blame] | 578 | } else { |
| 579 | /* Get the next timer wheel timer */ |
| 580 | next_jiffies = get_next_timer_interrupt(last_jiffies); |
| 581 | delta_jiffies = next_jiffies - last_jiffies; |
Paul E. McKenney | aa9b1630 | 2012-05-10 16:41:44 -0700 | [diff] [blame] | 582 | if (rcu_delta_jiffies < delta_jiffies) { |
| 583 | next_jiffies = last_jiffies + rcu_delta_jiffies; |
| 584 | delta_jiffies = rcu_delta_jiffies; |
| 585 | } |
Martin Schwidefsky | 3c5d92a | 2009-09-29 14:25:16 +0200 | [diff] [blame] | 586 | } |
Ingo Molnar | 47aa8b6 | 2013-04-26 10:05:59 +0200 | [diff] [blame] | 587 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 588 | /* |
Ingo Molnar | 47aa8b6 | 2013-04-26 10:05:59 +0200 | [diff] [blame] | 589 | * Do not stop the tick, if we are only one off (or less) |
| 590 | * or if the cpu is required for RCU: |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 591 | */ |
Ingo Molnar | 47aa8b6 | 2013-04-26 10:05:59 +0200 | [diff] [blame] | 592 | if (!ts->tick_stopped && delta_jiffies <= 1) |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 593 | goto out; |
| 594 | |
| 595 | /* Schedule the tick, if we are at least one jiffie off */ |
| 596 | if ((long)delta_jiffies >= 1) { |
| 597 | |
Woodruff, Richard | 0014744 | 2008-12-01 14:18:11 -0800 | [diff] [blame] | 598 | /* |
Woodruff, Richard | 0014744 | 2008-12-01 14:18:11 -0800 | [diff] [blame] | 599 | * If this cpu is the one which updates jiffies, then |
| 600 | * give up the assignment and let it be taken by the |
| 601 | * cpu which runs the tick timer next, which might be |
| 602 | * this cpu as well. If we don't drop this here the |
| 603 | * jiffies might be stale and do_timer() never |
Thomas Gleixner | 2718501 | 2009-11-12 22:12:06 +0100 | [diff] [blame] | 604 | * invoked. Keep track of the fact that it was the one |
| 605 | * which had the do_timer() duty last. If this cpu is |
| 606 | * the one which had the do_timer() duty last, we |
| 607 | * limit the sleep time to the timekeeping |
| 608 | * max_deferement value which we retrieved |
| 609 | * above. Otherwise we can sleep as long as we want. |
Woodruff, Richard | 0014744 | 2008-12-01 14:18:11 -0800 | [diff] [blame] | 610 | */ |
Thomas Gleixner | 2718501 | 2009-11-12 22:12:06 +0100 | [diff] [blame] | 611 | if (cpu == tick_do_timer_cpu) { |
Woodruff, Richard | 0014744 | 2008-12-01 14:18:11 -0800 | [diff] [blame] | 612 | tick_do_timer_cpu = TICK_DO_TIMER_NONE; |
Thomas Gleixner | 2718501 | 2009-11-12 22:12:06 +0100 | [diff] [blame] | 613 | ts->do_timer_last = 1; |
| 614 | } else if (tick_do_timer_cpu != TICK_DO_TIMER_NONE) { |
| 615 | time_delta = KTIME_MAX; |
| 616 | ts->do_timer_last = 0; |
| 617 | } else if (!ts->do_timer_last) { |
| 618 | time_delta = KTIME_MAX; |
| 619 | } |
| 620 | |
Frederic Weisbecker | 265f22a | 2013-05-03 03:39:05 +0200 | [diff] [blame] | 621 | #ifdef CONFIG_NO_HZ_FULL |
| 622 | if (!ts->inidle) { |
| 623 | time_delta = min(time_delta, |
| 624 | scheduler_tick_max_deferment()); |
| 625 | } |
| 626 | #endif |
| 627 | |
Thomas Gleixner | 2718501 | 2009-11-12 22:12:06 +0100 | [diff] [blame] | 628 | /* |
Jon Hunter | 9896246 | 2009-08-18 12:45:10 -0500 | [diff] [blame] | 629 | * calculate the expiry time for the next timer wheel |
| 630 | * timer. delta_jiffies >= NEXT_TIMER_MAX_DELTA signals |
| 631 | * that there is no timer pending or at least extremely |
| 632 | * far into the future (12 days for HZ=1000). In this |
| 633 | * case we set the expiry to the end of time. |
| 634 | */ |
| 635 | if (likely(delta_jiffies < NEXT_TIMER_MAX_DELTA)) { |
| 636 | /* |
| 637 | * Calculate the time delta for the next timer event. |
| 638 | * If the time delta exceeds the maximum time delta |
| 639 | * permitted by the current clocksource then adjust |
| 640 | * the time delta accordingly to ensure the |
| 641 | * clocksource does not wrap. |
| 642 | */ |
| 643 | time_delta = min_t(u64, time_delta, |
| 644 | tick_period.tv64 * delta_jiffies); |
Jon Hunter | 9896246 | 2009-08-18 12:45:10 -0500 | [diff] [blame] | 645 | } |
Woodruff, Richard | 0014744 | 2008-12-01 14:18:11 -0800 | [diff] [blame] | 646 | |
Thomas Gleixner | 2718501 | 2009-11-12 22:12:06 +0100 | [diff] [blame] | 647 | if (time_delta < KTIME_MAX) |
| 648 | expires = ktime_add_ns(last_update, time_delta); |
| 649 | else |
| 650 | expires.tv64 = KTIME_MAX; |
Woodruff, Richard | 0014744 | 2008-12-01 14:18:11 -0800 | [diff] [blame] | 651 | |
Woodruff, Richard | 0014744 | 2008-12-01 14:18:11 -0800 | [diff] [blame] | 652 | /* Skip reprogram of event if its not changed */ |
| 653 | if (ts->tick_stopped && ktime_equal(expires, dev->next_event)) |
| 654 | goto out; |
| 655 | |
Frederic Weisbecker | 84bf1bc | 2011-08-01 01:25:38 +0200 | [diff] [blame] | 656 | ret = expires; |
| 657 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 658 | /* |
| 659 | * nohz_stop_sched_tick can be called several times before |
| 660 | * the nohz_restart_sched_tick is called. This happens when |
| 661 | * interrupts arrive which do not cause a reschedule. In the |
| 662 | * first call we save the current tick time, so we can restart |
| 663 | * the scheduler tick in nohz_restart_sched_tick. |
| 664 | */ |
| 665 | if (!ts->tick_stopped) { |
Alex Shi | c1cc017 | 2012-09-10 15:10:58 +0800 | [diff] [blame] | 666 | nohz_balance_enter_idle(cpu); |
Peter Zijlstra | 5167e8d | 2012-06-22 15:52:09 +0200 | [diff] [blame] | 667 | calc_load_enter_idle(); |
Siddha, Suresh B | 46cb4b7 | 2007-05-08 00:32:51 -0700 | [diff] [blame] | 668 | |
Frederic Weisbecker | f5d411c | 2011-07-31 17:44:12 +0200 | [diff] [blame] | 669 | ts->last_tick = hrtimer_get_expires(&ts->sched_timer); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 670 | ts->tick_stopped = 1; |
Frederic Weisbecker | cb41a29 | 2013-04-20 17:35:50 +0200 | [diff] [blame] | 671 | trace_tick_stop(1, " "); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 672 | } |
Thomas Gleixner | d3ed782 | 2007-05-08 00:30:03 -0700 | [diff] [blame] | 673 | |
Thomas Gleixner | eaad084 | 2007-05-29 23:47:39 +0200 | [diff] [blame] | 674 | /* |
Jon Hunter | 9896246 | 2009-08-18 12:45:10 -0500 | [diff] [blame] | 675 | * If the expiration time == KTIME_MAX, then |
| 676 | * in this case we simply stop the tick timer. |
Thomas Gleixner | eaad084 | 2007-05-29 23:47:39 +0200 | [diff] [blame] | 677 | */ |
Jon Hunter | 9896246 | 2009-08-18 12:45:10 -0500 | [diff] [blame] | 678 | if (unlikely(expires.tv64 == KTIME_MAX)) { |
Thomas Gleixner | eaad084 | 2007-05-29 23:47:39 +0200 | [diff] [blame] | 679 | if (ts->nohz_mode == NOHZ_MODE_HIGHRES) |
| 680 | hrtimer_cancel(&ts->sched_timer); |
| 681 | goto out; |
| 682 | } |
| 683 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 684 | if (ts->nohz_mode == NOHZ_MODE_HIGHRES) { |
| 685 | hrtimer_start(&ts->sched_timer, expires, |
Arun R Bharadwaj | 5c33386 | 2009-04-16 12:14:37 +0530 | [diff] [blame] | 686 | HRTIMER_MODE_ABS_PINNED); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 687 | /* Check, if the timer was already in the past */ |
| 688 | if (hrtimer_active(&ts->sched_timer)) |
| 689 | goto out; |
Pavel Machek | 4c9dc64 | 2008-01-30 13:30:00 +0100 | [diff] [blame] | 690 | } else if (!tick_program_event(expires, 0)) |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 691 | goto out; |
| 692 | /* |
| 693 | * We are past the event already. So we crossed a |
| 694 | * jiffie boundary. Update jiffies and raise the |
| 695 | * softirq. |
| 696 | */ |
| 697 | tick_do_update_jiffies64(ktime_get()); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 698 | } |
| 699 | raise_softirq_irqoff(TIMER_SOFTIRQ); |
| 700 | out: |
| 701 | ts->next_jiffies = next_jiffies; |
| 702 | ts->last_jiffies = last_jiffies; |
Len Brown | 4f86d3a | 2007-10-03 18:58:00 -0400 | [diff] [blame] | 703 | ts->sleep_length = ktime_sub(dev->next_event, now); |
Frederic Weisbecker | 84bf1bc | 2011-08-01 01:25:38 +0200 | [diff] [blame] | 704 | |
| 705 | return ret; |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 706 | } |
| 707 | |
Frederic Weisbecker | 5811d99 | 2013-04-20 16:40:31 +0200 | [diff] [blame] | 708 | static void tick_nohz_full_stop_tick(struct tick_sched *ts) |
| 709 | { |
| 710 | #ifdef CONFIG_NO_HZ_FULL |
Alex Shi | e9a2eb4 | 2013-11-28 14:27:11 +0800 | [diff] [blame] | 711 | int cpu = smp_processor_id(); |
Frederic Weisbecker | 5811d99 | 2013-04-20 16:40:31 +0200 | [diff] [blame] | 712 | |
Alex Shi | e9a2eb4 | 2013-11-28 14:27:11 +0800 | [diff] [blame] | 713 | if (!tick_nohz_full_cpu(cpu) || is_idle_task(current)) |
| 714 | return; |
Frederic Weisbecker | 5811d99 | 2013-04-20 16:40:31 +0200 | [diff] [blame] | 715 | |
Alex Shi | e9a2eb4 | 2013-11-28 14:27:11 +0800 | [diff] [blame] | 716 | if (!ts->tick_stopped && ts->nohz_mode == NOHZ_MODE_INACTIVE) |
| 717 | return; |
Frederic Weisbecker | 5811d99 | 2013-04-20 16:40:31 +0200 | [diff] [blame] | 718 | |
Alex Shi | e9a2eb4 | 2013-11-28 14:27:11 +0800 | [diff] [blame] | 719 | if (!can_stop_full_tick()) |
| 720 | return; |
Frederic Weisbecker | 5811d99 | 2013-04-20 16:40:31 +0200 | [diff] [blame] | 721 | |
Alex Shi | e9a2eb4 | 2013-11-28 14:27:11 +0800 | [diff] [blame] | 722 | tick_nohz_stop_sched_tick(ts, ktime_get(), cpu); |
Frederic Weisbecker | 5811d99 | 2013-04-20 16:40:31 +0200 | [diff] [blame] | 723 | #endif |
| 724 | } |
| 725 | |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 726 | static bool can_stop_idle_tick(int cpu, struct tick_sched *ts) |
| 727 | { |
| 728 | /* |
| 729 | * If this cpu is offline and it is the one which updates |
| 730 | * jiffies, then give up the assignment and let it be taken by |
| 731 | * the cpu which runs the tick timer next. If we don't drop |
| 732 | * this here the jiffies might be stale and do_timer() never |
| 733 | * invoked. |
| 734 | */ |
| 735 | if (unlikely(!cpu_online(cpu))) { |
| 736 | if (cpu == tick_do_timer_cpu) |
| 737 | tick_do_timer_cpu = TICK_DO_TIMER_NONE; |
Thomas Gleixner | f7ea0fd | 2013-05-13 21:40:27 +0200 | [diff] [blame] | 738 | return false; |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 739 | } |
| 740 | |
Thomas Gleixner | 0e576acb | 2013-11-29 12:18:13 +0100 | [diff] [blame] | 741 | if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE)) { |
| 742 | ts->sleep_length = (ktime_t) { .tv64 = NSEC_PER_SEC/HZ }; |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 743 | return false; |
Thomas Gleixner | 0e576acb | 2013-11-29 12:18:13 +0100 | [diff] [blame] | 744 | } |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 745 | |
| 746 | if (need_resched()) |
| 747 | return false; |
| 748 | |
| 749 | if (unlikely(local_softirq_pending() && cpu_online(cpu))) { |
| 750 | static int ratelimit; |
| 751 | |
Paul E. McKenney | 803b0eb | 2012-08-23 08:34:07 -0700 | [diff] [blame] | 752 | if (ratelimit < 10 && |
| 753 | (local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK)) { |
Rado Vrbovsky | cfea7d7 | 2013-02-08 12:37:30 -0500 | [diff] [blame] | 754 | pr_warn("NOHZ: local_softirq_pending %02x\n", |
| 755 | (unsigned int) local_softirq_pending()); |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 756 | ratelimit++; |
| 757 | } |
| 758 | return false; |
| 759 | } |
| 760 | |
Frederic Weisbecker | 460775df | 2013-07-24 23:52:27 +0200 | [diff] [blame] | 761 | if (tick_nohz_full_enabled()) { |
Frederic Weisbecker | a382bf9 | 2012-12-18 18:24:35 +0100 | [diff] [blame] | 762 | /* |
| 763 | * Keep the tick alive to guarantee timekeeping progression |
| 764 | * if there are full dynticks CPUs around |
| 765 | */ |
| 766 | if (tick_do_timer_cpu == cpu) |
| 767 | return false; |
| 768 | /* |
| 769 | * Boot safety: make sure the timekeeping duty has been |
| 770 | * assigned before entering dyntick-idle mode, |
| 771 | */ |
| 772 | if (tick_do_timer_cpu == TICK_DO_TIMER_NONE) |
| 773 | return false; |
| 774 | } |
| 775 | |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 776 | return true; |
| 777 | } |
| 778 | |
Frederic Weisbecker | 19f5f73 | 2011-07-27 17:29:28 +0200 | [diff] [blame] | 779 | static void __tick_nohz_idle_enter(struct tick_sched *ts) |
| 780 | { |
Frederic Weisbecker | 84bf1bc | 2011-08-01 01:25:38 +0200 | [diff] [blame] | 781 | ktime_t now, expires; |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 782 | int cpu = smp_processor_id(); |
Frederic Weisbecker | 19f5f73 | 2011-07-27 17:29:28 +0200 | [diff] [blame] | 783 | |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 784 | now = tick_nohz_start_idle(ts); |
Frederic Weisbecker | 2ac0d98 | 2011-07-28 04:00:47 +0200 | [diff] [blame] | 785 | |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 786 | if (can_stop_idle_tick(cpu, ts)) { |
| 787 | int was_stopped = ts->tick_stopped; |
| 788 | |
| 789 | ts->idle_calls++; |
Frederic Weisbecker | 84bf1bc | 2011-08-01 01:25:38 +0200 | [diff] [blame] | 790 | |
| 791 | expires = tick_nohz_stop_sched_tick(ts, now, cpu); |
| 792 | if (expires.tv64 > 0LL) { |
| 793 | ts->idle_sleeps++; |
| 794 | ts->idle_expires = expires; |
| 795 | } |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 796 | |
| 797 | if (!was_stopped && ts->tick_stopped) |
| 798 | ts->idle_jiffies = ts->last_jiffies; |
| 799 | } |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 800 | } |
| 801 | |
| 802 | /** |
| 803 | * tick_nohz_idle_enter - stop the idle tick from the idle task |
| 804 | * |
| 805 | * When the next event is more than a tick into the future, stop the idle tick |
| 806 | * Called when we start the idle loop. |
Frederic Weisbecker | 2bbb681 | 2011-10-08 16:01:00 +0200 | [diff] [blame] | 807 | * |
Frederic Weisbecker | 1268fbc | 2011-11-17 18:48:14 +0100 | [diff] [blame] | 808 | * The arch is responsible of calling: |
Frederic Weisbecker | 2bbb681 | 2011-10-08 16:01:00 +0200 | [diff] [blame] | 809 | * |
| 810 | * - rcu_idle_enter() after its last use of RCU before the CPU is put |
| 811 | * to sleep. |
| 812 | * - 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] | 813 | */ |
Frederic Weisbecker | 1268fbc | 2011-11-17 18:48:14 +0100 | [diff] [blame] | 814 | void tick_nohz_idle_enter(void) |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 815 | { |
| 816 | struct tick_sched *ts; |
| 817 | |
Frederic Weisbecker | 1268fbc | 2011-11-17 18:48:14 +0100 | [diff] [blame] | 818 | WARN_ON_ONCE(irqs_disabled()); |
| 819 | |
Linus Torvalds | 0db49b7 | 2012-01-06 08:33:28 -0800 | [diff] [blame] | 820 | /* |
| 821 | * Update the idle state in the scheduler domain hierarchy |
| 822 | * when tick_nohz_stop_sched_tick() is called from the idle loop. |
| 823 | * State will be updated to busy during the first busy tick after |
| 824 | * exiting idle. |
| 825 | */ |
| 826 | set_cpu_sd_state_idle(); |
| 827 | |
Frederic Weisbecker | 1268fbc | 2011-11-17 18:48:14 +0100 | [diff] [blame] | 828 | local_irq_disable(); |
| 829 | |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 830 | ts = &__get_cpu_var(tick_cpu_sched); |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 831 | ts->inidle = 1; |
Frederic Weisbecker | 19f5f73 | 2011-07-27 17:29:28 +0200 | [diff] [blame] | 832 | __tick_nohz_idle_enter(ts); |
Frederic Weisbecker | 1268fbc | 2011-11-17 18:48:14 +0100 | [diff] [blame] | 833 | |
| 834 | local_irq_enable(); |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 835 | } |
Jacob Pan | 4dbd277 | 2013-01-04 11:12:43 +0000 | [diff] [blame] | 836 | EXPORT_SYMBOL_GPL(tick_nohz_idle_enter); |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 837 | |
| 838 | /** |
| 839 | * tick_nohz_irq_exit - update next tick event from interrupt exit |
| 840 | * |
| 841 | * When an interrupt fires while we are idle and it doesn't cause |
| 842 | * a reschedule, it may still add, modify or delete a timer, enqueue |
| 843 | * an RCU callback, etc... |
| 844 | * So we need to re-calculate and reprogram the next tick event. |
| 845 | */ |
| 846 | void tick_nohz_irq_exit(void) |
| 847 | { |
| 848 | struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched); |
| 849 | |
Rafael J. Wysocki | 1485191 | 2013-07-27 01:41:34 +0200 | [diff] [blame] | 850 | if (ts->inidle) |
Frederic Weisbecker | 5811d99 | 2013-04-20 16:40:31 +0200 | [diff] [blame] | 851 | __tick_nohz_idle_enter(ts); |
Rafael J. Wysocki | 1485191 | 2013-07-27 01:41:34 +0200 | [diff] [blame] | 852 | else |
Frederic Weisbecker | 5811d99 | 2013-04-20 16:40:31 +0200 | [diff] [blame] | 853 | tick_nohz_full_stop_tick(ts); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 854 | } |
| 855 | |
| 856 | /** |
Len Brown | 4f86d3a | 2007-10-03 18:58:00 -0400 | [diff] [blame] | 857 | * tick_nohz_get_sleep_length - return the length of the current sleep |
| 858 | * |
| 859 | * Called from power state control code with interrupts disabled |
| 860 | */ |
| 861 | ktime_t tick_nohz_get_sleep_length(void) |
| 862 | { |
| 863 | struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched); |
| 864 | |
| 865 | return ts->sleep_length; |
| 866 | } |
| 867 | |
Thomas Gleixner | c34bec5 | 2008-10-17 10:04:34 +0200 | [diff] [blame] | 868 | static void tick_nohz_restart(struct tick_sched *ts, ktime_t now) |
| 869 | { |
| 870 | hrtimer_cancel(&ts->sched_timer); |
Frederic Weisbecker | f5d411c | 2011-07-31 17:44:12 +0200 | [diff] [blame] | 871 | hrtimer_set_expires(&ts->sched_timer, ts->last_tick); |
Thomas Gleixner | c34bec5 | 2008-10-17 10:04:34 +0200 | [diff] [blame] | 872 | |
| 873 | while (1) { |
| 874 | /* Forward the time to expire in the future */ |
| 875 | hrtimer_forward(&ts->sched_timer, now, tick_period); |
| 876 | |
| 877 | if (ts->nohz_mode == NOHZ_MODE_HIGHRES) { |
Thomas Gleixner | 268a3dc | 2008-10-22 09:48:06 +0200 | [diff] [blame] | 878 | hrtimer_start_expires(&ts->sched_timer, |
Arun R Bharadwaj | 5c33386 | 2009-04-16 12:14:37 +0530 | [diff] [blame] | 879 | HRTIMER_MODE_ABS_PINNED); |
Thomas Gleixner | c34bec5 | 2008-10-17 10:04:34 +0200 | [diff] [blame] | 880 | /* Check, if the timer was already in the past */ |
| 881 | if (hrtimer_active(&ts->sched_timer)) |
| 882 | break; |
| 883 | } else { |
Thomas Gleixner | 268a3dc | 2008-10-22 09:48:06 +0200 | [diff] [blame] | 884 | if (!tick_program_event( |
| 885 | hrtimer_get_expires(&ts->sched_timer), 0)) |
Thomas Gleixner | c34bec5 | 2008-10-17 10:04:34 +0200 | [diff] [blame] | 886 | break; |
| 887 | } |
Neal Cardwell | 6f10392 | 2012-03-27 15:09:37 -0400 | [diff] [blame] | 888 | /* Reread time and update jiffies */ |
Thomas Gleixner | c34bec5 | 2008-10-17 10:04:34 +0200 | [diff] [blame] | 889 | now = ktime_get(); |
Neal Cardwell | 6f10392 | 2012-03-27 15:09:37 -0400 | [diff] [blame] | 890 | tick_do_update_jiffies64(now); |
Thomas Gleixner | c34bec5 | 2008-10-17 10:04:34 +0200 | [diff] [blame] | 891 | } |
| 892 | } |
| 893 | |
Frederic Weisbecker | 19f5f73 | 2011-07-27 17:29:28 +0200 | [diff] [blame] | 894 | 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] | 895 | { |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 896 | /* Update jiffies first */ |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 897 | tick_do_update_jiffies64(now); |
Peter Zijlstra | 5aaa0b7 | 2012-05-17 17:15:29 +0200 | [diff] [blame] | 898 | update_cpu_load_nohz(); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 899 | |
Charles Wang | 749c881 | 2012-08-20 16:02:33 +0800 | [diff] [blame] | 900 | calc_load_exit_idle(); |
Frederic Weisbecker | 2ac0d98 | 2011-07-28 04:00:47 +0200 | [diff] [blame] | 901 | touch_softlockup_watchdog(); |
| 902 | /* |
| 903 | * Cancel the scheduled timer and restore the tick |
| 904 | */ |
| 905 | ts->tick_stopped = 0; |
| 906 | ts->idle_exittime = now; |
| 907 | |
| 908 | tick_nohz_restart(ts, now); |
| 909 | } |
| 910 | |
| 911 | static void tick_nohz_account_idle_ticks(struct tick_sched *ts) |
| 912 | { |
Frederic Weisbecker | 3f4724e | 2012-07-16 18:00:34 +0200 | [diff] [blame] | 913 | #ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE |
Frederic Weisbecker | 2ac0d98 | 2011-07-28 04:00:47 +0200 | [diff] [blame] | 914 | unsigned long ticks; |
Frederic Weisbecker | 3f4724e | 2012-07-16 18:00:34 +0200 | [diff] [blame] | 915 | |
| 916 | if (vtime_accounting_enabled()) |
| 917 | return; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 918 | /* |
| 919 | * We stopped the tick in idle. Update process times would miss the |
| 920 | * time we slept as update_process_times does only a 1 tick |
| 921 | * accounting. Enforce that this is accounted to idle ! |
| 922 | */ |
| 923 | ticks = jiffies - ts->idle_jiffies; |
| 924 | /* |
| 925 | * We might be one off. Do not randomly account a huge number of ticks! |
| 926 | */ |
Martin Schwidefsky | 79741dd | 2008-12-31 15:11:38 +0100 | [diff] [blame] | 927 | if (ticks && ticks < LONG_MAX) |
| 928 | account_idle_ticks(ticks); |
| 929 | #endif |
Frederic Weisbecker | 19f5f73 | 2011-07-27 17:29:28 +0200 | [diff] [blame] | 930 | } |
| 931 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 932 | /** |
| 933 | * tick_nohz_idle_exit - restart the idle tick from the idle task |
| 934 | * |
| 935 | * Restart the idle tick when the CPU is woken up from idle |
| 936 | * This also exit the RCU extended quiescent state. The CPU |
| 937 | * can use RCU again after this function is called. |
| 938 | */ |
| 939 | void tick_nohz_idle_exit(void) |
| 940 | { |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 941 | struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 942 | ktime_t now; |
| 943 | |
| 944 | local_irq_disable(); |
| 945 | |
| 946 | WARN_ON_ONCE(!ts->inidle); |
| 947 | |
| 948 | ts->inidle = 0; |
| 949 | |
| 950 | if (ts->idle_active || ts->tick_stopped) |
| 951 | now = ktime_get(); |
| 952 | |
| 953 | if (ts->idle_active) |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 954 | tick_nohz_stop_idle(ts, now); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 955 | |
Frederic Weisbecker | 2ac0d98 | 2011-07-28 04:00:47 +0200 | [diff] [blame] | 956 | if (ts->tick_stopped) { |
Frederic Weisbecker | 19f5f73 | 2011-07-27 17:29:28 +0200 | [diff] [blame] | 957 | tick_nohz_restart_sched_tick(ts, now); |
Frederic Weisbecker | 2ac0d98 | 2011-07-28 04:00:47 +0200 | [diff] [blame] | 958 | tick_nohz_account_idle_ticks(ts); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 959 | } |
| 960 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 961 | local_irq_enable(); |
| 962 | } |
Jacob Pan | 4dbd277 | 2013-01-04 11:12:43 +0000 | [diff] [blame] | 963 | EXPORT_SYMBOL_GPL(tick_nohz_idle_exit); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 964 | |
| 965 | static int tick_nohz_reprogram(struct tick_sched *ts, ktime_t now) |
| 966 | { |
| 967 | hrtimer_forward(&ts->sched_timer, now, tick_period); |
Arjan van de Ven | cc584b2 | 2008-09-01 15:02:30 -0700 | [diff] [blame] | 968 | return tick_program_event(hrtimer_get_expires(&ts->sched_timer), 0); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 969 | } |
| 970 | |
| 971 | /* |
| 972 | * The nohz low res interrupt handler |
| 973 | */ |
| 974 | static void tick_nohz_handler(struct clock_event_device *dev) |
| 975 | { |
| 976 | struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched); |
| 977 | struct pt_regs *regs = get_irq_regs(); |
| 978 | ktime_t now = ktime_get(); |
| 979 | |
| 980 | dev->next_event.tv64 = KTIME_MAX; |
| 981 | |
Frederic Weisbecker | 5bb9622 | 2012-10-15 02:03:27 +0200 | [diff] [blame] | 982 | tick_sched_do_timer(now); |
Frederic Weisbecker | 9e8f559 | 2012-10-15 02:43:03 +0200 | [diff] [blame] | 983 | tick_sched_handle(ts, regs); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 984 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 985 | while (tick_nohz_reprogram(ts, now)) { |
| 986 | now = ktime_get(); |
| 987 | tick_do_update_jiffies64(now); |
| 988 | } |
| 989 | } |
| 990 | |
| 991 | /** |
| 992 | * tick_nohz_switch_to_nohz - switch to nohz mode |
| 993 | */ |
| 994 | static void tick_nohz_switch_to_nohz(void) |
| 995 | { |
| 996 | struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched); |
| 997 | ktime_t next; |
| 998 | |
Viresh Kumar | 2763053 | 2014-04-15 10:54:41 +0530 | [diff] [blame] | 999 | if (!tick_nohz_enabled) |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1000 | return; |
| 1001 | |
| 1002 | local_irq_disable(); |
| 1003 | if (tick_switch_to_oneshot(tick_nohz_handler)) { |
| 1004 | local_irq_enable(); |
| 1005 | return; |
| 1006 | } |
Thomas Gleixner | d689fe2 | 2013-11-13 21:01:57 +0100 | [diff] [blame] | 1007 | tick_nohz_active = 1; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1008 | ts->nohz_mode = NOHZ_MODE_LOWRES; |
| 1009 | |
| 1010 | /* |
| 1011 | * Recycle the hrtimer in ts, so we can share the |
| 1012 | * hrtimer_forward with the highres code. |
| 1013 | */ |
| 1014 | hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); |
| 1015 | /* Get the next period */ |
| 1016 | next = tick_init_jiffy_update(); |
| 1017 | |
| 1018 | for (;;) { |
Arjan van de Ven | cc584b2 | 2008-09-01 15:02:30 -0700 | [diff] [blame] | 1019 | hrtimer_set_expires(&ts->sched_timer, next); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1020 | if (!tick_program_event(next, 0)) |
| 1021 | break; |
| 1022 | next = ktime_add(next, tick_period); |
| 1023 | } |
| 1024 | local_irq_enable(); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1025 | } |
| 1026 | |
Thomas Gleixner | fb02fbc | 2008-10-17 10:01:23 +0200 | [diff] [blame] | 1027 | /* |
| 1028 | * When NOHZ is enabled and the tick is stopped, we need to kick the |
| 1029 | * tick timer from irq_enter() so that the jiffies update is kept |
| 1030 | * alive during long running softirqs. That's ugly as hell, but |
| 1031 | * correctness is key even if we need to fix the offending softirq in |
| 1032 | * the first place. |
| 1033 | * |
| 1034 | * Note, this is different to tick_nohz_restart. We just kick the |
| 1035 | * timer and do not touch the other magic bits which need to be done |
| 1036 | * when idle is left. |
| 1037 | */ |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 1038 | 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] | 1039 | { |
Thomas Gleixner | ae99286 | 2008-11-10 13:20:23 +0100 | [diff] [blame] | 1040 | #if 0 |
| 1041 | /* Switch back to 2.6.27 behaviour */ |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 1042 | ktime_t delta; |
Thomas Gleixner | fb02fbc | 2008-10-17 10:01:23 +0200 | [diff] [blame] | 1043 | |
Thomas Gleixner | c4bd822 | 2008-10-21 20:17:35 +0200 | [diff] [blame] | 1044 | /* |
| 1045 | * Do not touch the tick device, when the next expiry is either |
| 1046 | * already reached or less/equal than the tick period. |
| 1047 | */ |
Thomas Gleixner | 268a3dc | 2008-10-22 09:48:06 +0200 | [diff] [blame] | 1048 | delta = ktime_sub(hrtimer_get_expires(&ts->sched_timer), now); |
Thomas Gleixner | c4bd822 | 2008-10-21 20:17:35 +0200 | [diff] [blame] | 1049 | if (delta.tv64 <= tick_period.tv64) |
| 1050 | return; |
| 1051 | |
| 1052 | tick_nohz_restart(ts, now); |
Thomas Gleixner | ae99286 | 2008-11-10 13:20:23 +0100 | [diff] [blame] | 1053 | #endif |
Thomas Gleixner | fb02fbc | 2008-10-17 10:01:23 +0200 | [diff] [blame] | 1054 | } |
| 1055 | |
Frederic Weisbecker | 5acac1b | 2013-12-04 18:28:20 +0100 | [diff] [blame] | 1056 | static inline void tick_nohz_irq_enter(void) |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 1057 | { |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 1058 | struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched); |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 1059 | ktime_t now; |
| 1060 | |
| 1061 | if (!ts->idle_active && !ts->tick_stopped) |
| 1062 | return; |
| 1063 | now = ktime_get(); |
| 1064 | if (ts->idle_active) |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 1065 | tick_nohz_stop_idle(ts, now); |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 1066 | if (ts->tick_stopped) { |
| 1067 | tick_nohz_update_jiffies(now); |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 1068 | tick_nohz_kick_tick(ts, now); |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 1069 | } |
| 1070 | } |
| 1071 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1072 | #else |
| 1073 | |
| 1074 | static inline void tick_nohz_switch_to_nohz(void) { } |
Frederic Weisbecker | 5acac1b | 2013-12-04 18:28:20 +0100 | [diff] [blame] | 1075 | static inline void tick_nohz_irq_enter(void) { } |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1076 | |
Frederic Weisbecker | 3451d02 | 2011-08-10 23:21:01 +0200 | [diff] [blame] | 1077 | #endif /* CONFIG_NO_HZ_COMMON */ |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1078 | |
| 1079 | /* |
Thomas Gleixner | 719254fa | 2008-10-17 09:59:47 +0200 | [diff] [blame] | 1080 | * Called from irq_enter to notify about the possible interruption of idle() |
| 1081 | */ |
Frederic Weisbecker | 5acac1b | 2013-12-04 18:28:20 +0100 | [diff] [blame] | 1082 | void tick_irq_enter(void) |
Thomas Gleixner | 719254fa | 2008-10-17 09:59:47 +0200 | [diff] [blame] | 1083 | { |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 1084 | tick_check_oneshot_broadcast_this_cpu(); |
Frederic Weisbecker | 5acac1b | 2013-12-04 18:28:20 +0100 | [diff] [blame] | 1085 | tick_nohz_irq_enter(); |
Thomas Gleixner | 719254fa | 2008-10-17 09:59:47 +0200 | [diff] [blame] | 1086 | } |
| 1087 | |
| 1088 | /* |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1089 | * High resolution timer specific code |
| 1090 | */ |
| 1091 | #ifdef CONFIG_HIGH_RES_TIMERS |
| 1092 | /* |
Pavel Machek | 4c9dc64 | 2008-01-30 13:30:00 +0100 | [diff] [blame] | 1093 | * We rearm the timer until we get disabled by the idle code. |
Chuansheng Liu | 351f181 | 2012-10-25 01:07:35 +0800 | [diff] [blame] | 1094 | * Called with interrupts disabled. |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1095 | */ |
| 1096 | static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer) |
| 1097 | { |
| 1098 | struct tick_sched *ts = |
| 1099 | container_of(timer, struct tick_sched, sched_timer); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1100 | struct pt_regs *regs = get_irq_regs(); |
| 1101 | ktime_t now = ktime_get(); |
Thomas Gleixner | d3ed782 | 2007-05-08 00:30:03 -0700 | [diff] [blame] | 1102 | |
Frederic Weisbecker | 5bb9622 | 2012-10-15 02:03:27 +0200 | [diff] [blame] | 1103 | tick_sched_do_timer(now); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1104 | |
| 1105 | /* |
| 1106 | * Do not call, when we are not in irq context and have |
| 1107 | * no valid regs pointer |
| 1108 | */ |
Frederic Weisbecker | 9e8f559 | 2012-10-15 02:43:03 +0200 | [diff] [blame] | 1109 | if (regs) |
| 1110 | tick_sched_handle(ts, regs); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1111 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1112 | hrtimer_forward(timer, now, tick_period); |
| 1113 | |
| 1114 | return HRTIMER_RESTART; |
| 1115 | } |
| 1116 | |
Mike Galbraith | 5307c95 | 2012-05-08 12:20:58 +0200 | [diff] [blame] | 1117 | static int sched_skew_tick; |
| 1118 | |
Thomas Gleixner | 62cf20b | 2012-05-25 14:08:57 +0200 | [diff] [blame] | 1119 | static int __init skew_tick(char *str) |
| 1120 | { |
| 1121 | get_option(&str, &sched_skew_tick); |
| 1122 | |
| 1123 | return 0; |
| 1124 | } |
| 1125 | early_param("skew_tick", skew_tick); |
| 1126 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1127 | /** |
| 1128 | * tick_setup_sched_timer - setup the tick emulation timer |
| 1129 | */ |
| 1130 | void tick_setup_sched_timer(void) |
| 1131 | { |
| 1132 | struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched); |
| 1133 | ktime_t now = ktime_get(); |
| 1134 | |
| 1135 | /* |
| 1136 | * Emulate tick processing via per-CPU hrtimers: |
| 1137 | */ |
| 1138 | hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); |
| 1139 | ts->sched_timer.function = tick_sched_timer; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1140 | |
john stultz | 3704540 | 2007-07-21 04:37:35 -0700 | [diff] [blame] | 1141 | /* Get the next period (per cpu) */ |
Arjan van de Ven | cc584b2 | 2008-09-01 15:02:30 -0700 | [diff] [blame] | 1142 | hrtimer_set_expires(&ts->sched_timer, tick_init_jiffy_update()); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1143 | |
Thomas Gleixner | 9c3f9e2 | 2012-11-21 20:31:52 +0100 | [diff] [blame] | 1144 | /* Offset the tick to avert jiffies_lock contention. */ |
Mike Galbraith | 5307c95 | 2012-05-08 12:20:58 +0200 | [diff] [blame] | 1145 | if (sched_skew_tick) { |
| 1146 | u64 offset = ktime_to_ns(tick_period) >> 1; |
| 1147 | do_div(offset, num_possible_cpus()); |
| 1148 | offset *= smp_processor_id(); |
| 1149 | hrtimer_add_expires_ns(&ts->sched_timer, offset); |
| 1150 | } |
| 1151 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1152 | for (;;) { |
| 1153 | hrtimer_forward(&ts->sched_timer, now, tick_period); |
Arun R Bharadwaj | 5c33386 | 2009-04-16 12:14:37 +0530 | [diff] [blame] | 1154 | hrtimer_start_expires(&ts->sched_timer, |
| 1155 | HRTIMER_MODE_ABS_PINNED); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1156 | /* Check, if the timer was already in the past */ |
| 1157 | if (hrtimer_active(&ts->sched_timer)) |
| 1158 | break; |
| 1159 | now = ktime_get(); |
| 1160 | } |
| 1161 | |
Frederic Weisbecker | 3451d02 | 2011-08-10 23:21:01 +0200 | [diff] [blame] | 1162 | #ifdef CONFIG_NO_HZ_COMMON |
Thomas Gleixner | d689fe2 | 2013-11-13 21:01:57 +0100 | [diff] [blame] | 1163 | if (tick_nohz_enabled) { |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1164 | ts->nohz_mode = NOHZ_MODE_HIGHRES; |
Thomas Gleixner | d689fe2 | 2013-11-13 21:01:57 +0100 | [diff] [blame] | 1165 | tick_nohz_active = 1; |
| 1166 | } |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1167 | #endif |
| 1168 | } |
Miao Xie | 3c4fbe5 | 2008-08-20 16:37:38 -0700 | [diff] [blame] | 1169 | #endif /* HIGH_RES_TIMERS */ |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1170 | |
Frederic Weisbecker | 3451d02 | 2011-08-10 23:21:01 +0200 | [diff] [blame] | 1171 | #if defined CONFIG_NO_HZ_COMMON || defined CONFIG_HIGH_RES_TIMERS |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1172 | void tick_cancel_sched_timer(int cpu) |
| 1173 | { |
| 1174 | struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); |
| 1175 | |
Miao Xie | 3c4fbe5 | 2008-08-20 16:37:38 -0700 | [diff] [blame] | 1176 | # ifdef CONFIG_HIGH_RES_TIMERS |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1177 | if (ts->sched_timer.base) |
| 1178 | hrtimer_cancel(&ts->sched_timer); |
Miao Xie | 3c4fbe5 | 2008-08-20 16:37:38 -0700 | [diff] [blame] | 1179 | # endif |
Karsten Wiese | a790176 | 2008-03-04 14:59:55 -0800 | [diff] [blame] | 1180 | |
Thomas Gleixner | 4b0c0f2 | 2013-05-03 15:02:50 +0200 | [diff] [blame] | 1181 | memset(ts, 0, sizeof(*ts)); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1182 | } |
Miao Xie | 3c4fbe5 | 2008-08-20 16:37:38 -0700 | [diff] [blame] | 1183 | #endif |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1184 | |
| 1185 | /** |
| 1186 | * Async notification about clocksource changes |
| 1187 | */ |
| 1188 | void tick_clock_notify(void) |
| 1189 | { |
| 1190 | int cpu; |
| 1191 | |
| 1192 | for_each_possible_cpu(cpu) |
| 1193 | set_bit(0, &per_cpu(tick_cpu_sched, cpu).check_clocks); |
| 1194 | } |
| 1195 | |
| 1196 | /* |
| 1197 | * Async notification about clock event changes |
| 1198 | */ |
| 1199 | void tick_oneshot_notify(void) |
| 1200 | { |
| 1201 | struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched); |
| 1202 | |
| 1203 | set_bit(0, &ts->check_clocks); |
| 1204 | } |
| 1205 | |
| 1206 | /** |
| 1207 | * Check, if a change happened, which makes oneshot possible. |
| 1208 | * |
| 1209 | * Called cyclic from the hrtimer softirq (driven by the timer |
| 1210 | * softirq) allow_nohz signals, that we can switch into low-res nohz |
| 1211 | * mode, because high resolution timers are disabled (either compile |
| 1212 | * or runtime). |
| 1213 | */ |
| 1214 | int tick_check_oneshot_change(int allow_nohz) |
| 1215 | { |
| 1216 | struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched); |
| 1217 | |
| 1218 | if (!test_and_clear_bit(0, &ts->check_clocks)) |
| 1219 | return 0; |
| 1220 | |
| 1221 | if (ts->nohz_mode != NOHZ_MODE_INACTIVE) |
| 1222 | return 0; |
| 1223 | |
Li Zefan | cf4fc6c | 2008-02-08 04:19:24 -0800 | [diff] [blame] | 1224 | if (!timekeeping_valid_for_hres() || !tick_is_oneshot_available()) |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1225 | return 0; |
| 1226 | |
| 1227 | if (!allow_nohz) |
| 1228 | return 1; |
| 1229 | |
| 1230 | tick_nohz_switch_to_nohz(); |
| 1231 | return 0; |
| 1232 | } |