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 | */ |
Thomas Gleixner | c1797ba | 2015-03-25 13:07:37 +0100 | [diff] [blame] | 37 | static DEFINE_PER_CPU(struct tick_sched, tick_cpu_sched); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 38 | |
Ingo Molnar | 289f480 | 2007-02-16 01:28:15 -0800 | [diff] [blame] | 39 | struct tick_sched *tick_get_tick_sched(int cpu) |
| 40 | { |
| 41 | return &per_cpu(tick_cpu_sched, cpu); |
| 42 | } |
| 43 | |
Arnd Bergmann | 7809998a | 2016-01-25 16:41:49 +0100 | [diff] [blame] | 44 | #if defined(CONFIG_NO_HZ_COMMON) || defined(CONFIG_HIGH_RES_TIMERS) |
| 45 | /* |
| 46 | * The time, when the last jiffy update happened. Protected by jiffies_lock. |
| 47 | */ |
| 48 | static ktime_t last_jiffies_update; |
| 49 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 50 | /* |
| 51 | * Must be called with interrupts disabled ! |
| 52 | */ |
| 53 | static void tick_do_update_jiffies64(ktime_t now) |
| 54 | { |
| 55 | unsigned long ticks = 0; |
| 56 | ktime_t delta; |
| 57 | |
Ingo Molnar | 7a14ce1 | 2008-05-12 15:43:53 +0200 | [diff] [blame] | 58 | /* |
John Stultz | d6ad418 | 2012-02-28 16:50:11 -0800 | [diff] [blame] | 59 | * Do a quick check without holding jiffies_lock: |
Ingo Molnar | 7a14ce1 | 2008-05-12 15:43:53 +0200 | [diff] [blame] | 60 | */ |
| 61 | delta = ktime_sub(now, last_jiffies_update); |
| 62 | if (delta.tv64 < tick_period.tv64) |
| 63 | return; |
| 64 | |
John Stultz | d6ad418 | 2012-02-28 16:50:11 -0800 | [diff] [blame] | 65 | /* Reevalute with jiffies_lock held */ |
| 66 | write_seqlock(&jiffies_lock); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 67 | |
| 68 | delta = ktime_sub(now, last_jiffies_update); |
| 69 | if (delta.tv64 >= tick_period.tv64) { |
| 70 | |
| 71 | delta = ktime_sub(delta, tick_period); |
| 72 | last_jiffies_update = ktime_add(last_jiffies_update, |
| 73 | tick_period); |
| 74 | |
| 75 | /* Slow path for long timeouts */ |
| 76 | if (unlikely(delta.tv64 >= tick_period.tv64)) { |
| 77 | s64 incr = ktime_to_ns(tick_period); |
| 78 | |
| 79 | ticks = ktime_divns(delta, incr); |
| 80 | |
| 81 | last_jiffies_update = ktime_add_ns(last_jiffies_update, |
| 82 | incr * ticks); |
| 83 | } |
| 84 | do_timer(++ticks); |
Thomas Gleixner | 49d670f | 2008-09-22 18:56:01 +0200 | [diff] [blame] | 85 | |
| 86 | /* Keep the tick_next_period variable up to date */ |
| 87 | tick_next_period = ktime_add(last_jiffies_update, tick_period); |
Viresh Kumar | 03e6bdc | 2014-04-15 10:54:40 +0530 | [diff] [blame] | 88 | } else { |
| 89 | write_sequnlock(&jiffies_lock); |
| 90 | return; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 91 | } |
John Stultz | d6ad418 | 2012-02-28 16:50:11 -0800 | [diff] [blame] | 92 | write_sequnlock(&jiffies_lock); |
John Stultz | 47a1b796 | 2013-12-12 13:10:55 -0800 | [diff] [blame] | 93 | update_wall_time(); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 94 | } |
| 95 | |
| 96 | /* |
| 97 | * Initialize and return retrieve the jiffies update. |
| 98 | */ |
| 99 | static ktime_t tick_init_jiffy_update(void) |
| 100 | { |
| 101 | ktime_t period; |
| 102 | |
John Stultz | d6ad418 | 2012-02-28 16:50:11 -0800 | [diff] [blame] | 103 | write_seqlock(&jiffies_lock); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 104 | /* Did we start the jiffies update yet ? */ |
| 105 | if (last_jiffies_update.tv64 == 0) |
| 106 | last_jiffies_update = tick_next_period; |
| 107 | period = last_jiffies_update; |
John Stultz | d6ad418 | 2012-02-28 16:50:11 -0800 | [diff] [blame] | 108 | write_sequnlock(&jiffies_lock); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 109 | return period; |
| 110 | } |
| 111 | |
Frederic Weisbecker | 5bb9622 | 2012-10-15 02:03:27 +0200 | [diff] [blame] | 112 | |
| 113 | static void tick_sched_do_timer(ktime_t now) |
| 114 | { |
| 115 | int cpu = smp_processor_id(); |
| 116 | |
Frederic Weisbecker | 3451d02 | 2011-08-10 23:21:01 +0200 | [diff] [blame] | 117 | #ifdef CONFIG_NO_HZ_COMMON |
Frederic Weisbecker | 5bb9622 | 2012-10-15 02:03:27 +0200 | [diff] [blame] | 118 | /* |
| 119 | * Check if the do_timer duty was dropped. We don't care about |
| 120 | * concurrency: This happens only when the cpu in charge went |
| 121 | * into a long sleep. If two cpus happen to assign themself to |
| 122 | * this duty, then the jiffies update is still serialized by |
Thomas Gleixner | 9c3f9e2 | 2012-11-21 20:31:52 +0100 | [diff] [blame] | 123 | * jiffies_lock. |
Frederic Weisbecker | 5bb9622 | 2012-10-15 02:03:27 +0200 | [diff] [blame] | 124 | */ |
Frederic Weisbecker | a382bf9 | 2012-12-18 18:24:35 +0100 | [diff] [blame] | 125 | if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE) |
Frederic Weisbecker | c5bfece | 2013-04-12 16:45:34 +0200 | [diff] [blame] | 126 | && !tick_nohz_full_cpu(cpu)) |
Frederic Weisbecker | 5bb9622 | 2012-10-15 02:03:27 +0200 | [diff] [blame] | 127 | tick_do_timer_cpu = cpu; |
| 128 | #endif |
| 129 | |
| 130 | /* Check, if the jiffies need an update */ |
| 131 | if (tick_do_timer_cpu == cpu) |
| 132 | tick_do_update_jiffies64(now); |
| 133 | } |
| 134 | |
Frederic Weisbecker | 9e8f559 | 2012-10-15 02:43:03 +0200 | [diff] [blame] | 135 | static void tick_sched_handle(struct tick_sched *ts, struct pt_regs *regs) |
| 136 | { |
Frederic Weisbecker | 3451d02 | 2011-08-10 23:21:01 +0200 | [diff] [blame] | 137 | #ifdef CONFIG_NO_HZ_COMMON |
Frederic Weisbecker | 9e8f559 | 2012-10-15 02:43:03 +0200 | [diff] [blame] | 138 | /* |
| 139 | * When we are idle and the tick is stopped, we have to touch |
| 140 | * the watchdog as we might not schedule for a really long |
| 141 | * time. This happens on complete idle SMP systems while |
| 142 | * waiting on the login prompt. We also increment the "start of |
| 143 | * idle" jiffy stamp so the idle accounting adjustment we do |
| 144 | * when we go busy again does not account too much ticks. |
| 145 | */ |
| 146 | if (ts->tick_stopped) { |
Tejun Heo | 03e0d46 | 2015-12-08 11:28:04 -0500 | [diff] [blame] | 147 | touch_softlockup_watchdog_sched(); |
Frederic Weisbecker | 9e8f559 | 2012-10-15 02:43:03 +0200 | [diff] [blame] | 148 | if (is_idle_task(current)) |
| 149 | ts->idle_jiffies++; |
| 150 | } |
Frederic Weisbecker | 94a5714 | 2012-10-15 16:17:16 +0200 | [diff] [blame] | 151 | #endif |
Frederic Weisbecker | 9e8f559 | 2012-10-15 02:43:03 +0200 | [diff] [blame] | 152 | update_process_times(user_mode(regs)); |
| 153 | profile_tick(CPU_PROFILING); |
| 154 | } |
Arnd Bergmann | 7809998a | 2016-01-25 16:41:49 +0100 | [diff] [blame] | 155 | #endif |
Frederic Weisbecker | 9e8f559 | 2012-10-15 02:43:03 +0200 | [diff] [blame] | 156 | |
Frederic Weisbecker | c5bfece | 2013-04-12 16:45:34 +0200 | [diff] [blame] | 157 | #ifdef CONFIG_NO_HZ_FULL |
Frederic Weisbecker | 460775d | 2013-07-24 23:52:27 +0200 | [diff] [blame] | 158 | cpumask_var_t tick_nohz_full_mask; |
Paul E. McKenney | c0f489d | 2014-06-04 13:46:03 -0700 | [diff] [blame] | 159 | cpumask_var_t housekeeping_mask; |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 160 | bool tick_nohz_full_running; |
Frederic Weisbecker | d027d45 | 2015-06-07 15:54:30 +0200 | [diff] [blame^] | 161 | static unsigned long tick_dep_mask; |
Frederic Weisbecker | a831881 | 2012-12-18 17:32:19 +0100 | [diff] [blame] | 162 | |
Frederic Weisbecker | d027d45 | 2015-06-07 15:54:30 +0200 | [diff] [blame^] | 163 | static void trace_tick_dependency(unsigned long dep) |
| 164 | { |
| 165 | if (dep & TICK_DEP_MASK_POSIX_TIMER) { |
| 166 | trace_tick_stop(0, "posix timers running\n"); |
| 167 | return; |
| 168 | } |
| 169 | |
| 170 | if (dep & TICK_DEP_MASK_PERF_EVENTS) { |
| 171 | trace_tick_stop(0, "perf events running\n"); |
| 172 | return; |
| 173 | } |
| 174 | |
| 175 | if (dep & TICK_DEP_MASK_SCHED) { |
| 176 | trace_tick_stop(0, "more than 1 task in runqueue\n"); |
| 177 | return; |
| 178 | } |
| 179 | |
| 180 | if (dep & TICK_DEP_MASK_CLOCK_UNSTABLE) |
| 181 | trace_tick_stop(0, "unstable sched clock\n"); |
| 182 | } |
| 183 | |
| 184 | static bool can_stop_full_tick(struct tick_sched *ts) |
Frederic Weisbecker | 9014c45 | 2013-04-20 15:43:57 +0200 | [diff] [blame] | 185 | { |
| 186 | WARN_ON_ONCE(!irqs_disabled()); |
| 187 | |
Frederic Weisbecker | d027d45 | 2015-06-07 15:54:30 +0200 | [diff] [blame^] | 188 | if (tick_dep_mask) { |
| 189 | trace_tick_dependency(tick_dep_mask); |
| 190 | return false; |
| 191 | } |
| 192 | |
| 193 | if (ts->tick_dep_mask) { |
| 194 | trace_tick_dependency(ts->tick_dep_mask); |
| 195 | return false; |
| 196 | } |
| 197 | |
| 198 | if (current->tick_dep_mask) { |
| 199 | trace_tick_dependency(current->tick_dep_mask); |
| 200 | return false; |
| 201 | } |
| 202 | |
| 203 | if (current->signal->tick_dep_mask) { |
| 204 | trace_tick_dependency(current->signal->tick_dep_mask); |
| 205 | return false; |
| 206 | } |
| 207 | |
Frederic Weisbecker | cb41a29 | 2013-04-20 17:35:50 +0200 | [diff] [blame] | 208 | if (!sched_can_stop_tick()) { |
| 209 | trace_tick_stop(0, "more than 1 task in runqueue\n"); |
Frederic Weisbecker | 9014c45 | 2013-04-20 15:43:57 +0200 | [diff] [blame] | 210 | return false; |
Frederic Weisbecker | cb41a29 | 2013-04-20 17:35:50 +0200 | [diff] [blame] | 211 | } |
Frederic Weisbecker | 9014c45 | 2013-04-20 15:43:57 +0200 | [diff] [blame] | 212 | |
Frederic Weisbecker | cb41a29 | 2013-04-20 17:35:50 +0200 | [diff] [blame] | 213 | if (!posix_cpu_timers_can_stop_tick(current)) { |
| 214 | trace_tick_stop(0, "posix timers running\n"); |
Frederic Weisbecker | 9014c45 | 2013-04-20 15:43:57 +0200 | [diff] [blame] | 215 | return false; |
Frederic Weisbecker | cb41a29 | 2013-04-20 17:35:50 +0200 | [diff] [blame] | 216 | } |
Frederic Weisbecker | 9014c45 | 2013-04-20 15:43:57 +0200 | [diff] [blame] | 217 | |
Frederic Weisbecker | cb41a29 | 2013-04-20 17:35:50 +0200 | [diff] [blame] | 218 | if (!perf_event_can_stop_tick()) { |
| 219 | trace_tick_stop(0, "perf events running\n"); |
Frederic Weisbecker | 9014c45 | 2013-04-20 15:43:57 +0200 | [diff] [blame] | 220 | return false; |
Frederic Weisbecker | cb41a29 | 2013-04-20 17:35:50 +0200 | [diff] [blame] | 221 | } |
Frederic Weisbecker | 9014c45 | 2013-04-20 15:43:57 +0200 | [diff] [blame] | 222 | |
Frederic Weisbecker | 9014c45 | 2013-04-20 15:43:57 +0200 | [diff] [blame] | 223 | #ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK |
| 224 | /* |
Frederic Weisbecker | d027d45 | 2015-06-07 15:54:30 +0200 | [diff] [blame^] | 225 | * sched_clock_tick() needs us? |
| 226 | * |
Frederic Weisbecker | 9014c45 | 2013-04-20 15:43:57 +0200 | [diff] [blame] | 227 | * TODO: kick full dynticks CPUs when |
| 228 | * sched_clock_stable is set. |
| 229 | */ |
Peter Zijlstra | 35af99e | 2013-11-28 19:38:42 +0100 | [diff] [blame] | 230 | if (!sched_clock_stable()) { |
Frederic Weisbecker | cb41a29 | 2013-04-20 17:35:50 +0200 | [diff] [blame] | 231 | trace_tick_stop(0, "unstable sched clock\n"); |
Steven Rostedt | e12d027 | 2013-05-10 17:12:28 -0400 | [diff] [blame] | 232 | /* |
| 233 | * Don't allow the user to think they can get |
| 234 | * full NO_HZ with this machine. |
| 235 | */ |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 236 | WARN_ONCE(tick_nohz_full_running, |
Steven Rostedt | 543487c | 2013-07-16 10:22:12 -0400 | [diff] [blame] | 237 | "NO_HZ FULL will not work with unstable sched clock"); |
Frederic Weisbecker | 9014c45 | 2013-04-20 15:43:57 +0200 | [diff] [blame] | 238 | return false; |
Frederic Weisbecker | cb41a29 | 2013-04-20 17:35:50 +0200 | [diff] [blame] | 239 | } |
Frederic Weisbecker | 9014c45 | 2013-04-20 15:43:57 +0200 | [diff] [blame] | 240 | #endif |
| 241 | |
| 242 | return true; |
| 243 | } |
| 244 | |
Frederic Weisbecker | d027d45 | 2015-06-07 15:54:30 +0200 | [diff] [blame^] | 245 | static void nohz_full_kick_func(struct irq_work *work) |
Frederic Weisbecker | 76c24fb | 2013-04-18 00:15:40 +0200 | [diff] [blame] | 246 | { |
Frederic Weisbecker | 73738a9 | 2015-05-27 19:22:08 +0200 | [diff] [blame] | 247 | /* Empty, the tick restart happens on tick_nohz_irq_exit() */ |
Frederic Weisbecker | 76c24fb | 2013-04-18 00:15:40 +0200 | [diff] [blame] | 248 | } |
| 249 | |
| 250 | static DEFINE_PER_CPU(struct irq_work, nohz_full_kick_work) = { |
Frederic Weisbecker | d027d45 | 2015-06-07 15:54:30 +0200 | [diff] [blame^] | 251 | .func = nohz_full_kick_func, |
Frederic Weisbecker | 76c24fb | 2013-04-18 00:15:40 +0200 | [diff] [blame] | 252 | }; |
| 253 | |
| 254 | /* |
Frederic Weisbecker | 40bea03 | 2014-08-13 18:50:16 +0200 | [diff] [blame] | 255 | * Kick this CPU if it's full dynticks in order to force it to |
| 256 | * re-evaluate its dependency on the tick and restart it if necessary. |
| 257 | * This kick, unlike tick_nohz_full_kick_cpu() and tick_nohz_full_kick_all(), |
| 258 | * is NMI safe. |
| 259 | */ |
| 260 | void tick_nohz_full_kick(void) |
| 261 | { |
| 262 | if (!tick_nohz_full_cpu(smp_processor_id())) |
| 263 | return; |
| 264 | |
Christoph Lameter | 56e4dea | 2014-10-27 10:49:45 -0500 | [diff] [blame] | 265 | irq_work_queue(this_cpu_ptr(&nohz_full_kick_work)); |
Frederic Weisbecker | 40bea03 | 2014-08-13 18:50:16 +0200 | [diff] [blame] | 266 | } |
| 267 | |
| 268 | /* |
Frederic Weisbecker | 3d36aeb | 2014-06-04 16:17:33 +0200 | [diff] [blame] | 269 | * 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] | 270 | * re-evaluate its dependency on the tick and restart it if necessary. |
| 271 | */ |
Frederic Weisbecker | 3d36aeb | 2014-06-04 16:17:33 +0200 | [diff] [blame] | 272 | void tick_nohz_full_kick_cpu(int cpu) |
Frederic Weisbecker | 76c24fb | 2013-04-18 00:15:40 +0200 | [diff] [blame] | 273 | { |
Frederic Weisbecker | 3d36aeb | 2014-06-04 16:17:33 +0200 | [diff] [blame] | 274 | if (!tick_nohz_full_cpu(cpu)) |
| 275 | return; |
| 276 | |
| 277 | irq_work_queue_on(&per_cpu(nohz_full_kick_work, cpu), cpu); |
Frederic Weisbecker | 76c24fb | 2013-04-18 00:15:40 +0200 | [diff] [blame] | 278 | } |
| 279 | |
Frederic Weisbecker | 76c24fb | 2013-04-18 00:15:40 +0200 | [diff] [blame] | 280 | /* |
| 281 | * Kick all full dynticks CPUs in order to force these to re-evaluate |
| 282 | * their dependency on the tick and restart it if necessary. |
| 283 | */ |
| 284 | void tick_nohz_full_kick_all(void) |
| 285 | { |
Frederic Weisbecker | 8537bb9 | 2015-12-07 16:55:23 +0100 | [diff] [blame] | 286 | int cpu; |
| 287 | |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 288 | if (!tick_nohz_full_running) |
Frederic Weisbecker | 76c24fb | 2013-04-18 00:15:40 +0200 | [diff] [blame] | 289 | return; |
| 290 | |
| 291 | preempt_disable(); |
Frederic Weisbecker | 8537bb9 | 2015-12-07 16:55:23 +0100 | [diff] [blame] | 292 | for_each_cpu_and(cpu, tick_nohz_full_mask, cpu_online_mask) |
| 293 | tick_nohz_full_kick_cpu(cpu); |
Frederic Weisbecker | 76c24fb | 2013-04-18 00:15:40 +0200 | [diff] [blame] | 294 | preempt_enable(); |
| 295 | } |
| 296 | |
Frederic Weisbecker | d027d45 | 2015-06-07 15:54:30 +0200 | [diff] [blame^] | 297 | static void tick_nohz_dep_set_all(unsigned long *dep, |
| 298 | enum tick_dep_bits bit) |
| 299 | { |
| 300 | unsigned long prev; |
| 301 | |
| 302 | prev = fetch_or(dep, BIT_MASK(bit)); |
| 303 | if (!prev) |
| 304 | tick_nohz_full_kick_all(); |
| 305 | } |
| 306 | |
| 307 | /* |
| 308 | * Set a global tick dependency. Used by perf events that rely on freq and |
| 309 | * by unstable clock. |
| 310 | */ |
| 311 | void tick_nohz_dep_set(enum tick_dep_bits bit) |
| 312 | { |
| 313 | tick_nohz_dep_set_all(&tick_dep_mask, bit); |
| 314 | } |
| 315 | |
| 316 | void tick_nohz_dep_clear(enum tick_dep_bits bit) |
| 317 | { |
| 318 | clear_bit(bit, &tick_dep_mask); |
| 319 | } |
| 320 | |
| 321 | /* |
| 322 | * Set per-CPU tick dependency. Used by scheduler and perf events in order to |
| 323 | * manage events throttling. |
| 324 | */ |
| 325 | void tick_nohz_dep_set_cpu(int cpu, enum tick_dep_bits bit) |
| 326 | { |
| 327 | unsigned long prev; |
| 328 | struct tick_sched *ts; |
| 329 | |
| 330 | ts = per_cpu_ptr(&tick_cpu_sched, cpu); |
| 331 | |
| 332 | prev = fetch_or(&ts->tick_dep_mask, BIT_MASK(bit)); |
| 333 | if (!prev) { |
| 334 | preempt_disable(); |
| 335 | /* Perf needs local kick that is NMI safe */ |
| 336 | if (cpu == smp_processor_id()) { |
| 337 | tick_nohz_full_kick(); |
| 338 | } else { |
| 339 | /* Remote irq work not NMI-safe */ |
| 340 | if (!WARN_ON_ONCE(in_nmi())) |
| 341 | tick_nohz_full_kick_cpu(cpu); |
| 342 | } |
| 343 | preempt_enable(); |
| 344 | } |
| 345 | } |
| 346 | |
| 347 | void tick_nohz_dep_clear_cpu(int cpu, enum tick_dep_bits bit) |
| 348 | { |
| 349 | struct tick_sched *ts = per_cpu_ptr(&tick_cpu_sched, cpu); |
| 350 | |
| 351 | clear_bit(bit, &ts->tick_dep_mask); |
| 352 | } |
| 353 | |
| 354 | /* |
| 355 | * Set a per-task tick dependency. Posix CPU timers need this in order to elapse |
| 356 | * per task timers. |
| 357 | */ |
| 358 | void tick_nohz_dep_set_task(struct task_struct *tsk, enum tick_dep_bits bit) |
| 359 | { |
| 360 | /* |
| 361 | * We could optimize this with just kicking the target running the task |
| 362 | * if that noise matters for nohz full users. |
| 363 | */ |
| 364 | tick_nohz_dep_set_all(&tsk->tick_dep_mask, bit); |
| 365 | } |
| 366 | |
| 367 | void tick_nohz_dep_clear_task(struct task_struct *tsk, enum tick_dep_bits bit) |
| 368 | { |
| 369 | clear_bit(bit, &tsk->tick_dep_mask); |
| 370 | } |
| 371 | |
| 372 | /* |
| 373 | * Set a per-taskgroup tick dependency. Posix CPU timers need this in order to elapse |
| 374 | * per process timers. |
| 375 | */ |
| 376 | void tick_nohz_dep_set_signal(struct signal_struct *sig, enum tick_dep_bits bit) |
| 377 | { |
| 378 | tick_nohz_dep_set_all(&sig->tick_dep_mask, bit); |
| 379 | } |
| 380 | |
| 381 | void tick_nohz_dep_clear_signal(struct signal_struct *sig, enum tick_dep_bits bit) |
| 382 | { |
| 383 | clear_bit(bit, &sig->tick_dep_mask); |
| 384 | } |
| 385 | |
Frederic Weisbecker | 99e5ada | 2013-04-20 17:11:50 +0200 | [diff] [blame] | 386 | /* |
| 387 | * Re-evaluate the need for the tick as we switch the current task. |
| 388 | * It might need the tick due to per task/process properties: |
| 389 | * perf events, posix cpu timers, ... |
| 390 | */ |
Frederic Weisbecker | de734f8 | 2015-06-11 18:07:12 +0200 | [diff] [blame] | 391 | void __tick_nohz_task_switch(void) |
Frederic Weisbecker | 99e5ada | 2013-04-20 17:11:50 +0200 | [diff] [blame] | 392 | { |
| 393 | unsigned long flags; |
Frederic Weisbecker | d027d45 | 2015-06-07 15:54:30 +0200 | [diff] [blame^] | 394 | struct tick_sched *ts; |
Frederic Weisbecker | 99e5ada | 2013-04-20 17:11:50 +0200 | [diff] [blame] | 395 | |
Frederic Weisbecker | 99e5ada | 2013-04-20 17:11:50 +0200 | [diff] [blame] | 396 | local_irq_save(flags); |
| 397 | |
Li Zhong | 6296ace | 2013-04-28 11:25:58 +0800 | [diff] [blame] | 398 | if (!tick_nohz_full_cpu(smp_processor_id())) |
| 399 | goto out; |
| 400 | |
Frederic Weisbecker | d027d45 | 2015-06-07 15:54:30 +0200 | [diff] [blame^] | 401 | ts = this_cpu_ptr(&tick_cpu_sched); |
Frederic Weisbecker | 99e5ada | 2013-04-20 17:11:50 +0200 | [diff] [blame] | 402 | |
Frederic Weisbecker | d027d45 | 2015-06-07 15:54:30 +0200 | [diff] [blame^] | 403 | if (ts->tick_stopped) { |
| 404 | if (current->tick_dep_mask || current->signal->tick_dep_mask) |
| 405 | tick_nohz_full_kick(); |
| 406 | } |
Li Zhong | 6296ace | 2013-04-28 11:25:58 +0800 | [diff] [blame] | 407 | out: |
Frederic Weisbecker | 99e5ada | 2013-04-20 17:11:50 +0200 | [diff] [blame] | 408 | local_irq_restore(flags); |
| 409 | } |
| 410 | |
Frederic Weisbecker | a831881 | 2012-12-18 17:32:19 +0100 | [diff] [blame] | 411 | /* Parse the boot-time nohz CPU list from the kernel parameters. */ |
Frederic Weisbecker | c5bfece | 2013-04-12 16:45:34 +0200 | [diff] [blame] | 412 | static int __init tick_nohz_full_setup(char *str) |
Frederic Weisbecker | a831881 | 2012-12-18 17:32:19 +0100 | [diff] [blame] | 413 | { |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 414 | alloc_bootmem_cpumask_var(&tick_nohz_full_mask); |
| 415 | if (cpulist_parse(str, tick_nohz_full_mask) < 0) { |
Frederic Weisbecker | c5bfece | 2013-04-12 16:45:34 +0200 | [diff] [blame] | 416 | pr_warning("NOHZ: Incorrect nohz_full cpumask\n"); |
Frederic Weisbecker | 4327b15 | 2014-08-17 22:02:55 +0200 | [diff] [blame] | 417 | free_bootmem_cpumask_var(tick_nohz_full_mask); |
Frederic Weisbecker | 0453b43 | 2013-03-27 02:18:34 +0100 | [diff] [blame] | 418 | return 1; |
| 419 | } |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 420 | tick_nohz_full_running = true; |
Frederic Weisbecker | 0453b43 | 2013-03-27 02:18:34 +0100 | [diff] [blame] | 421 | |
Frederic Weisbecker | a831881 | 2012-12-18 17:32:19 +0100 | [diff] [blame] | 422 | return 1; |
| 423 | } |
Frederic Weisbecker | c5bfece | 2013-04-12 16:45:34 +0200 | [diff] [blame] | 424 | __setup("nohz_full=", tick_nohz_full_setup); |
Frederic Weisbecker | a831881 | 2012-12-18 17:32:19 +0100 | [diff] [blame] | 425 | |
Paul Gortmaker | 0db0628 | 2013-06-19 14:53:51 -0400 | [diff] [blame] | 426 | static int tick_nohz_cpu_down_callback(struct notifier_block *nfb, |
Frederic Weisbecker | 7c8bb6c | 2015-09-01 16:51:00 +0200 | [diff] [blame] | 427 | unsigned long action, |
| 428 | void *hcpu) |
Frederic Weisbecker | a382bf9 | 2012-12-18 18:24:35 +0100 | [diff] [blame] | 429 | { |
| 430 | unsigned int cpu = (unsigned long)hcpu; |
| 431 | |
| 432 | switch (action & ~CPU_TASKS_FROZEN) { |
| 433 | case CPU_DOWN_PREPARE: |
| 434 | /* |
Frederic Weisbecker | 7c8bb6c | 2015-09-01 16:51:00 +0200 | [diff] [blame] | 435 | * The boot CPU handles housekeeping duty (unbound timers, |
| 436 | * workqueues, timekeeping, ...) on behalf of full dynticks |
| 437 | * CPUs. It must remain online when nohz full is enabled. |
Frederic Weisbecker | a382bf9 | 2012-12-18 18:24:35 +0100 | [diff] [blame] | 438 | */ |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 439 | if (tick_nohz_full_running && tick_do_timer_cpu == cpu) |
Li Zhong | 1a7f829 | 2013-05-17 16:44:04 +0800 | [diff] [blame] | 440 | return NOTIFY_BAD; |
Frederic Weisbecker | a382bf9 | 2012-12-18 18:24:35 +0100 | [diff] [blame] | 441 | break; |
| 442 | } |
| 443 | return NOTIFY_OK; |
| 444 | } |
| 445 | |
Frederic Weisbecker | f98823a | 2013-03-27 01:17:22 +0100 | [diff] [blame] | 446 | static int tick_nohz_init_all(void) |
| 447 | { |
| 448 | int err = -1; |
| 449 | |
| 450 | #ifdef CONFIG_NO_HZ_FULL_ALL |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 451 | if (!alloc_cpumask_var(&tick_nohz_full_mask, GFP_KERNEL)) { |
Frederic Weisbecker | 4327b15 | 2014-08-17 22:02:55 +0200 | [diff] [blame] | 452 | WARN(1, "NO_HZ: Can't allocate full dynticks cpumask\n"); |
Paul E. McKenney | c0f489d | 2014-06-04 13:46:03 -0700 | [diff] [blame] | 453 | return err; |
| 454 | } |
Frederic Weisbecker | f98823a | 2013-03-27 01:17:22 +0100 | [diff] [blame] | 455 | err = 0; |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 456 | cpumask_setall(tick_nohz_full_mask); |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 457 | tick_nohz_full_running = true; |
Frederic Weisbecker | f98823a | 2013-03-27 01:17:22 +0100 | [diff] [blame] | 458 | #endif |
| 459 | return err; |
| 460 | } |
| 461 | |
Frederic Weisbecker | d1e43fa | 2013-03-26 23:47:24 +0100 | [diff] [blame] | 462 | void __init tick_nohz_init(void) |
Frederic Weisbecker | a831881 | 2012-12-18 17:32:19 +0100 | [diff] [blame] | 463 | { |
Frederic Weisbecker | d1e43fa | 2013-03-26 23:47:24 +0100 | [diff] [blame] | 464 | int cpu; |
| 465 | |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 466 | if (!tick_nohz_full_running) { |
Frederic Weisbecker | f98823a | 2013-03-27 01:17:22 +0100 | [diff] [blame] | 467 | if (tick_nohz_init_all() < 0) |
| 468 | return; |
| 469 | } |
Frederic Weisbecker | d1e43fa | 2013-03-26 23:47:24 +0100 | [diff] [blame] | 470 | |
Frederic Weisbecker | 4327b15 | 2014-08-17 22:02:55 +0200 | [diff] [blame] | 471 | if (!alloc_cpumask_var(&housekeeping_mask, GFP_KERNEL)) { |
| 472 | WARN(1, "NO_HZ: Can't allocate not-full dynticks cpumask\n"); |
| 473 | cpumask_clear(tick_nohz_full_mask); |
| 474 | tick_nohz_full_running = false; |
| 475 | return; |
| 476 | } |
| 477 | |
Frederic Weisbecker | 9b01f5b | 2014-08-18 01:36:07 +0200 | [diff] [blame] | 478 | /* |
| 479 | * Full dynticks uses irq work to drive the tick rescheduling on safe |
| 480 | * locking contexts. But then we need irq work to raise its own |
| 481 | * interrupts to avoid circular dependency on the tick |
| 482 | */ |
| 483 | if (!arch_irq_work_has_interrupt()) { |
| 484 | pr_warning("NO_HZ: Can't run full dynticks because arch doesn't " |
| 485 | "support irq work self-IPIs\n"); |
| 486 | cpumask_clear(tick_nohz_full_mask); |
| 487 | cpumask_copy(housekeeping_mask, cpu_possible_mask); |
| 488 | tick_nohz_full_running = false; |
| 489 | return; |
| 490 | } |
| 491 | |
Frederic Weisbecker | 4327b15 | 2014-08-17 22:02:55 +0200 | [diff] [blame] | 492 | cpu = smp_processor_id(); |
| 493 | |
| 494 | if (cpumask_test_cpu(cpu, tick_nohz_full_mask)) { |
| 495 | pr_warning("NO_HZ: Clearing %d from nohz_full range for timekeeping\n", cpu); |
| 496 | cpumask_clear_cpu(cpu, tick_nohz_full_mask); |
| 497 | } |
| 498 | |
| 499 | cpumask_andnot(housekeeping_mask, |
| 500 | cpu_possible_mask, tick_nohz_full_mask); |
| 501 | |
Frederic Weisbecker | 73867dc | 2013-07-24 23:31:00 +0200 | [diff] [blame] | 502 | for_each_cpu(cpu, tick_nohz_full_mask) |
Frederic Weisbecker | 2e70933 | 2013-07-10 00:55:25 +0200 | [diff] [blame] | 503 | context_tracking_cpu_set(cpu); |
| 504 | |
Frederic Weisbecker | d1e43fa | 2013-03-26 23:47:24 +0100 | [diff] [blame] | 505 | cpu_notifier(tick_nohz_cpu_down_callback, 0); |
Tejun Heo | ffda22c | 2015-02-13 14:37:31 -0800 | [diff] [blame] | 506 | pr_info("NO_HZ: Full dynticks CPUs: %*pbl.\n", |
| 507 | cpumask_pr_args(tick_nohz_full_mask)); |
Frederic Weisbecker | 7c8bb6c | 2015-09-01 16:51:00 +0200 | [diff] [blame] | 508 | |
| 509 | /* |
| 510 | * We need at least one CPU to handle housekeeping work such |
| 511 | * as timekeeping, unbound timers, workqueues, ... |
| 512 | */ |
| 513 | WARN_ON_ONCE(cpumask_empty(housekeeping_mask)); |
Frederic Weisbecker | a831881 | 2012-12-18 17:32:19 +0100 | [diff] [blame] | 514 | } |
Frederic Weisbecker | a831881 | 2012-12-18 17:32:19 +0100 | [diff] [blame] | 515 | #endif |
| 516 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 517 | /* |
| 518 | * NOHZ - aka dynamic tick functionality |
| 519 | */ |
Frederic Weisbecker | 3451d02 | 2011-08-10 23:21:01 +0200 | [diff] [blame] | 520 | #ifdef CONFIG_NO_HZ_COMMON |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 521 | /* |
| 522 | * NO HZ enabled ? |
| 523 | */ |
Jean Delvare | 46373a1 | 2016-01-11 17:40:31 +0100 | [diff] [blame] | 524 | int tick_nohz_enabled __read_mostly = 1; |
Thomas Gleixner | bc7a34b | 2015-05-26 22:50:33 +0000 | [diff] [blame] | 525 | unsigned long tick_nohz_active __read_mostly; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 526 | /* |
| 527 | * Enable / Disable tickless mode |
| 528 | */ |
| 529 | static int __init setup_tick_nohz(char *str) |
| 530 | { |
| 531 | if (!strcmp(str, "off")) |
| 532 | tick_nohz_enabled = 0; |
| 533 | else if (!strcmp(str, "on")) |
| 534 | tick_nohz_enabled = 1; |
| 535 | else |
| 536 | return 0; |
| 537 | return 1; |
| 538 | } |
| 539 | |
| 540 | __setup("nohz=", setup_tick_nohz); |
| 541 | |
Thomas Gleixner | c1797ba | 2015-03-25 13:07:37 +0100 | [diff] [blame] | 542 | int tick_nohz_tick_stopped(void) |
| 543 | { |
| 544 | return __this_cpu_read(tick_cpu_sched.tick_stopped); |
| 545 | } |
| 546 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 547 | /** |
| 548 | * tick_nohz_update_jiffies - update jiffies when idle was interrupted |
| 549 | * |
| 550 | * Called from interrupt entry when the CPU was idle |
| 551 | * |
| 552 | * In case the sched_tick was stopped on this CPU, we have to check if jiffies |
| 553 | * must be updated. Otherwise an interrupt handler could use a stale jiffy |
| 554 | * value. We do this unconditionally on any cpu, as we don't know whether the |
| 555 | * cpu, which has the update task assigned is in a long sleep. |
| 556 | */ |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 557 | static void tick_nohz_update_jiffies(ktime_t now) |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 558 | { |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 559 | unsigned long flags; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 560 | |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 561 | __this_cpu_write(tick_cpu_sched.idle_waketime, now); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 562 | |
| 563 | local_irq_save(flags); |
| 564 | tick_do_update_jiffies64(now); |
| 565 | local_irq_restore(flags); |
Ingo Molnar | 02ff375 | 2008-05-12 15:43:53 +0200 | [diff] [blame] | 566 | |
Tejun Heo | 03e0d46 | 2015-12-08 11:28:04 -0500 | [diff] [blame] | 567 | touch_softlockup_watchdog_sched(); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 568 | } |
| 569 | |
Arjan van de Ven | 595aac4 | 2010-05-09 08:22:45 -0700 | [diff] [blame] | 570 | /* |
| 571 | * Updates the per cpu time idle statistics counters |
| 572 | */ |
Arjan van de Ven | 8d63bf9 | 2010-05-09 08:24:03 -0700 | [diff] [blame] | 573 | static void |
Peter Zijlstra | 8c215bd | 2010-07-01 09:07:17 +0200 | [diff] [blame] | 574 | 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] | 575 | { |
| 576 | ktime_t delta; |
| 577 | |
Arjan van de Ven | 595aac4 | 2010-05-09 08:22:45 -0700 | [diff] [blame] | 578 | if (ts->idle_active) { |
| 579 | delta = ktime_sub(now, ts->idle_entrytime); |
Peter Zijlstra | 8c215bd | 2010-07-01 09:07:17 +0200 | [diff] [blame] | 580 | if (nr_iowait_cpu(cpu) > 0) |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 581 | ts->iowait_sleeptime = ktime_add(ts->iowait_sleeptime, delta); |
Michal Hocko | 6beea0c | 2011-08-24 09:37:48 +0200 | [diff] [blame] | 582 | else |
| 583 | ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta); |
Arjan van de Ven | 8c7b09f | 2010-05-09 08:23:23 -0700 | [diff] [blame] | 584 | ts->idle_entrytime = now; |
Arjan van de Ven | 595aac4 | 2010-05-09 08:22:45 -0700 | [diff] [blame] | 585 | } |
Arjan van de Ven | 8d63bf9 | 2010-05-09 08:24:03 -0700 | [diff] [blame] | 586 | |
Arjan van de Ven | e0e37c2 | 2010-05-09 08:24:39 -0700 | [diff] [blame] | 587 | if (last_update_time) |
Arjan van de Ven | 8d63bf9 | 2010-05-09 08:24:03 -0700 | [diff] [blame] | 588 | *last_update_time = ktime_to_us(now); |
| 589 | |
Arjan van de Ven | 595aac4 | 2010-05-09 08:22:45 -0700 | [diff] [blame] | 590 | } |
| 591 | |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 592 | 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] | 593 | { |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 594 | update_ts_time_stats(smp_processor_id(), ts, now, NULL); |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 595 | ts->idle_active = 0; |
Peter Zijlstra | 56c7426 | 2008-09-01 16:44:23 +0200 | [diff] [blame] | 596 | |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 597 | sched_clock_idle_wakeup_event(0); |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 598 | } |
| 599 | |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 600 | static ktime_t tick_nohz_start_idle(struct tick_sched *ts) |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 601 | { |
Michal Hocko | 430ee88 | 2011-12-01 17:00:22 +0100 | [diff] [blame] | 602 | ktime_t now = ktime_get(); |
Arjan van de Ven | 595aac4 | 2010-05-09 08:22:45 -0700 | [diff] [blame] | 603 | |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 604 | ts->idle_entrytime = now; |
| 605 | ts->idle_active = 1; |
Peter Zijlstra | 56c7426 | 2008-09-01 16:44:23 +0200 | [diff] [blame] | 606 | sched_clock_idle_sleep_event(); |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 607 | return now; |
| 608 | } |
| 609 | |
Arjan van de Ven | b1f724c | 2010-05-09 08:22:08 -0700 | [diff] [blame] | 610 | /** |
| 611 | * get_cpu_idle_time_us - get the total idle time of a cpu |
| 612 | * @cpu: CPU number to query |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 613 | * @last_update_time: variable to store update time in. Do not update |
| 614 | * counters if NULL. |
Arjan van de Ven | b1f724c | 2010-05-09 08:22:08 -0700 | [diff] [blame] | 615 | * |
| 616 | * Return the cummulative idle time (since boot) for a given |
Michal Hocko | 6beea0c | 2011-08-24 09:37:48 +0200 | [diff] [blame] | 617 | * CPU, in microseconds. |
Arjan van de Ven | b1f724c | 2010-05-09 08:22:08 -0700 | [diff] [blame] | 618 | * |
| 619 | * This time is measured via accounting rather than sampling, |
| 620 | * and is as accurate as ktime_get() is. |
| 621 | * |
| 622 | * This function returns -1 if NOHZ is not enabled. |
| 623 | */ |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 624 | u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time) |
| 625 | { |
| 626 | struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 627 | ktime_t now, idle; |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 628 | |
Thomas Gleixner | d689fe2 | 2013-11-13 21:01:57 +0100 | [diff] [blame] | 629 | if (!tick_nohz_active) |
venkatesh.pallipadi@intel.com | 8083e4a | 2008-08-04 11:59:11 -0700 | [diff] [blame] | 630 | return -1; |
| 631 | |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 632 | now = ktime_get(); |
| 633 | if (last_update_time) { |
| 634 | update_ts_time_stats(cpu, ts, now, last_update_time); |
| 635 | idle = ts->idle_sleeptime; |
| 636 | } else { |
| 637 | if (ts->idle_active && !nr_iowait_cpu(cpu)) { |
| 638 | ktime_t delta = ktime_sub(now, ts->idle_entrytime); |
venkatesh.pallipadi@intel.com | 8083e4a | 2008-08-04 11:59:11 -0700 | [diff] [blame] | 639 | |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 640 | idle = ktime_add(ts->idle_sleeptime, delta); |
| 641 | } else { |
| 642 | idle = ts->idle_sleeptime; |
| 643 | } |
| 644 | } |
| 645 | |
| 646 | return ktime_to_us(idle); |
| 647 | |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 648 | } |
venkatesh.pallipadi@intel.com | 8083e4a | 2008-08-04 11:59:11 -0700 | [diff] [blame] | 649 | EXPORT_SYMBOL_GPL(get_cpu_idle_time_us); |
Venki Pallipadi | 6378ddb | 2008-01-30 13:30:04 +0100 | [diff] [blame] | 650 | |
Michal Hocko | 6beea0c | 2011-08-24 09:37:48 +0200 | [diff] [blame] | 651 | /** |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 652 | * get_cpu_iowait_time_us - get the total iowait time of a cpu |
| 653 | * @cpu: CPU number to query |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 654 | * @last_update_time: variable to store update time in. Do not update |
| 655 | * counters if NULL. |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 656 | * |
| 657 | * Return the cummulative iowait time (since boot) for a given |
| 658 | * CPU, in microseconds. |
| 659 | * |
| 660 | * This time is measured via accounting rather than sampling, |
| 661 | * and is as accurate as ktime_get() is. |
| 662 | * |
| 663 | * This function returns -1 if NOHZ is not enabled. |
| 664 | */ |
| 665 | u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time) |
| 666 | { |
| 667 | struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 668 | ktime_t now, iowait; |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 669 | |
Thomas Gleixner | d689fe2 | 2013-11-13 21:01:57 +0100 | [diff] [blame] | 670 | if (!tick_nohz_active) |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 671 | return -1; |
| 672 | |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 673 | now = ktime_get(); |
| 674 | if (last_update_time) { |
| 675 | update_ts_time_stats(cpu, ts, now, last_update_time); |
| 676 | iowait = ts->iowait_sleeptime; |
| 677 | } else { |
| 678 | if (ts->idle_active && nr_iowait_cpu(cpu) > 0) { |
| 679 | ktime_t delta = ktime_sub(now, ts->idle_entrytime); |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 680 | |
Michal Hocko | 09a1d34 | 2011-08-24 09:39:30 +0200 | [diff] [blame] | 681 | iowait = ktime_add(ts->iowait_sleeptime, delta); |
| 682 | } else { |
| 683 | iowait = ts->iowait_sleeptime; |
| 684 | } |
| 685 | } |
| 686 | |
| 687 | return ktime_to_us(iowait); |
Arjan van de Ven | 0224cf4 | 2010-05-09 08:25:23 -0700 | [diff] [blame] | 688 | } |
| 689 | EXPORT_SYMBOL_GPL(get_cpu_iowait_time_us); |
| 690 | |
Thomas Gleixner | 0ff53d0 | 2015-04-14 21:08:54 +0000 | [diff] [blame] | 691 | static void tick_nohz_restart(struct tick_sched *ts, ktime_t now) |
| 692 | { |
| 693 | hrtimer_cancel(&ts->sched_timer); |
| 694 | hrtimer_set_expires(&ts->sched_timer, ts->last_tick); |
| 695 | |
| 696 | /* Forward the time to expire in the future */ |
| 697 | hrtimer_forward(&ts->sched_timer, now, tick_period); |
| 698 | |
| 699 | if (ts->nohz_mode == NOHZ_MODE_HIGHRES) |
| 700 | hrtimer_start_expires(&ts->sched_timer, HRTIMER_MODE_ABS_PINNED); |
| 701 | else |
| 702 | tick_program_event(hrtimer_get_expires(&ts->sched_timer), 1); |
| 703 | } |
| 704 | |
Frederic Weisbecker | 84bf1bc | 2011-08-01 01:25:38 +0200 | [diff] [blame] | 705 | static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts, |
| 706 | ktime_t now, int cpu) |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 707 | { |
Christoph Lameter | 22127e9 | 2014-08-17 12:30:25 -0500 | [diff] [blame] | 708 | struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev); |
Thomas Gleixner | c1ad348 | 2015-04-14 21:08:58 +0000 | [diff] [blame] | 709 | u64 basemono, next_tick, next_tmr, next_rcu, delta, expires; |
| 710 | unsigned long seq, basejiff; |
| 711 | ktime_t tick; |
Frederic Weisbecker | 855a0fc | 2013-12-17 00:16:37 +0100 | [diff] [blame] | 712 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 713 | /* Read jiffies and the time when jiffies were updated last */ |
| 714 | do { |
John Stultz | d6ad418 | 2012-02-28 16:50:11 -0800 | [diff] [blame] | 715 | seq = read_seqbegin(&jiffies_lock); |
Thomas Gleixner | c1ad348 | 2015-04-14 21:08:58 +0000 | [diff] [blame] | 716 | basemono = last_jiffies_update.tv64; |
| 717 | basejiff = jiffies; |
John Stultz | d6ad418 | 2012-02-28 16:50:11 -0800 | [diff] [blame] | 718 | } while (read_seqretry(&jiffies_lock, seq)); |
Thomas Gleixner | c1ad348 | 2015-04-14 21:08:58 +0000 | [diff] [blame] | 719 | ts->last_jiffies = basejiff; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 720 | |
Thomas Gleixner | c1ad348 | 2015-04-14 21:08:58 +0000 | [diff] [blame] | 721 | if (rcu_needs_cpu(basemono, &next_rcu) || |
Martin Schwidefsky | fe0f497 | 2014-09-30 17:37:52 +0200 | [diff] [blame] | 722 | arch_needs_cpu() || irq_work_needs_cpu()) { |
Thomas Gleixner | c1ad348 | 2015-04-14 21:08:58 +0000 | [diff] [blame] | 723 | next_tick = basemono + TICK_NSEC; |
Martin Schwidefsky | 3c5d92a | 2009-09-29 14:25:16 +0200 | [diff] [blame] | 724 | } else { |
Thomas Gleixner | c1ad348 | 2015-04-14 21:08:58 +0000 | [diff] [blame] | 725 | /* |
| 726 | * Get the next pending timer. If high resolution |
| 727 | * timers are enabled this only takes the timer wheel |
| 728 | * timers into account. If high resolution timers are |
| 729 | * disabled this also looks at the next expiring |
| 730 | * hrtimer. |
| 731 | */ |
| 732 | next_tmr = get_next_timer_interrupt(basejiff, basemono); |
| 733 | ts->next_timer = next_tmr; |
| 734 | /* Take the next rcu event into account */ |
| 735 | next_tick = next_rcu < next_tmr ? next_rcu : next_tmr; |
Martin Schwidefsky | 3c5d92a | 2009-09-29 14:25:16 +0200 | [diff] [blame] | 736 | } |
Ingo Molnar | 47aa8b6 | 2013-04-26 10:05:59 +0200 | [diff] [blame] | 737 | |
Thomas Gleixner | c1ad348 | 2015-04-14 21:08:58 +0000 | [diff] [blame] | 738 | /* |
| 739 | * If the tick is due in the next period, keep it ticking or |
Peter Zijlstra | 82bbe34 | 2015-11-19 17:21:06 +0100 | [diff] [blame] | 740 | * force prod the timer. |
Thomas Gleixner | c1ad348 | 2015-04-14 21:08:58 +0000 | [diff] [blame] | 741 | */ |
| 742 | delta = next_tick - basemono; |
| 743 | if (delta <= (u64)TICK_NSEC) { |
| 744 | tick.tv64 = 0; |
Peter Zijlstra | 82bbe34 | 2015-11-19 17:21:06 +0100 | [diff] [blame] | 745 | /* |
| 746 | * We've not stopped the tick yet, and there's a timer in the |
| 747 | * next period, so no point in stopping it either, bail. |
| 748 | */ |
Thomas Gleixner | 157d29e | 2015-04-14 21:08:56 +0000 | [diff] [blame] | 749 | if (!ts->tick_stopped) |
Woodruff, Richard | 0014744 | 2008-12-01 14:18:11 -0800 | [diff] [blame] | 750 | goto out; |
Peter Zijlstra | 82bbe34 | 2015-11-19 17:21:06 +0100 | [diff] [blame] | 751 | |
| 752 | /* |
| 753 | * If, OTOH, we did stop it, but there's a pending (expired) |
| 754 | * timer reprogram the timer hardware to fire now. |
| 755 | * |
| 756 | * We will not restart the tick proper, just prod the timer |
| 757 | * hardware into firing an interrupt to process the pending |
| 758 | * timers. Just like tick_irq_exit() will not restart the tick |
| 759 | * for 'normal' interrupts. |
| 760 | * |
| 761 | * Only once we exit the idle loop will we re-enable the tick, |
| 762 | * see tick_nohz_idle_exit(). |
| 763 | */ |
Thomas Gleixner | c1ad348 | 2015-04-14 21:08:58 +0000 | [diff] [blame] | 764 | if (delta == 0) { |
Thomas Gleixner | 157d29e | 2015-04-14 21:08:56 +0000 | [diff] [blame] | 765 | tick_nohz_restart(ts, now); |
Thomas Gleixner | eaad084 | 2007-05-29 23:47:39 +0200 | [diff] [blame] | 766 | goto out; |
Thomas Gleixner | 157d29e | 2015-04-14 21:08:56 +0000 | [diff] [blame] | 767 | } |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 768 | } |
Thomas Gleixner | 0ff53d0 | 2015-04-14 21:08:54 +0000 | [diff] [blame] | 769 | |
Thomas Gleixner | 157d29e | 2015-04-14 21:08:56 +0000 | [diff] [blame] | 770 | /* |
| 771 | * If this cpu is the one which updates jiffies, then give up |
| 772 | * the assignment and let it be taken by the cpu which runs |
| 773 | * the tick timer next, which might be this cpu as well. If we |
| 774 | * don't drop this here the jiffies might be stale and |
| 775 | * do_timer() never invoked. Keep track of the fact that it |
| 776 | * was the one which had the do_timer() duty last. If this cpu |
| 777 | * is the one which had the do_timer() duty last, we limit the |
Thomas Gleixner | c1ad348 | 2015-04-14 21:08:58 +0000 | [diff] [blame] | 778 | * sleep time to the timekeeping max_deferement value. |
| 779 | * Otherwise we can sleep as long as we want. |
Thomas Gleixner | 157d29e | 2015-04-14 21:08:56 +0000 | [diff] [blame] | 780 | */ |
Thomas Gleixner | c1ad348 | 2015-04-14 21:08:58 +0000 | [diff] [blame] | 781 | delta = timekeeping_max_deferment(); |
Thomas Gleixner | 157d29e | 2015-04-14 21:08:56 +0000 | [diff] [blame] | 782 | if (cpu == tick_do_timer_cpu) { |
| 783 | tick_do_timer_cpu = TICK_DO_TIMER_NONE; |
| 784 | ts->do_timer_last = 1; |
| 785 | } else if (tick_do_timer_cpu != TICK_DO_TIMER_NONE) { |
Thomas Gleixner | c1ad348 | 2015-04-14 21:08:58 +0000 | [diff] [blame] | 786 | delta = KTIME_MAX; |
Thomas Gleixner | 157d29e | 2015-04-14 21:08:56 +0000 | [diff] [blame] | 787 | ts->do_timer_last = 0; |
| 788 | } else if (!ts->do_timer_last) { |
Thomas Gleixner | c1ad348 | 2015-04-14 21:08:58 +0000 | [diff] [blame] | 789 | delta = KTIME_MAX; |
Thomas Gleixner | 157d29e | 2015-04-14 21:08:56 +0000 | [diff] [blame] | 790 | } |
| 791 | |
| 792 | #ifdef CONFIG_NO_HZ_FULL |
Thomas Gleixner | c1ad348 | 2015-04-14 21:08:58 +0000 | [diff] [blame] | 793 | /* Limit the tick delta to the maximum scheduler deferment */ |
Thomas Gleixner | 157d29e | 2015-04-14 21:08:56 +0000 | [diff] [blame] | 794 | if (!ts->inidle) |
Thomas Gleixner | c1ad348 | 2015-04-14 21:08:58 +0000 | [diff] [blame] | 795 | delta = min(delta, scheduler_tick_max_deferment()); |
Thomas Gleixner | 157d29e | 2015-04-14 21:08:56 +0000 | [diff] [blame] | 796 | #endif |
| 797 | |
Thomas Gleixner | c1ad348 | 2015-04-14 21:08:58 +0000 | [diff] [blame] | 798 | /* Calculate the next expiry time */ |
| 799 | if (delta < (KTIME_MAX - basemono)) |
| 800 | expires = basemono + delta; |
Thomas Gleixner | 157d29e | 2015-04-14 21:08:56 +0000 | [diff] [blame] | 801 | else |
Thomas Gleixner | c1ad348 | 2015-04-14 21:08:58 +0000 | [diff] [blame] | 802 | expires = KTIME_MAX; |
| 803 | |
| 804 | expires = min_t(u64, expires, next_tick); |
| 805 | tick.tv64 = expires; |
Thomas Gleixner | 157d29e | 2015-04-14 21:08:56 +0000 | [diff] [blame] | 806 | |
| 807 | /* Skip reprogram of event if its not changed */ |
Thomas Gleixner | c1ad348 | 2015-04-14 21:08:58 +0000 | [diff] [blame] | 808 | if (ts->tick_stopped && (expires == dev->next_event.tv64)) |
Thomas Gleixner | 157d29e | 2015-04-14 21:08:56 +0000 | [diff] [blame] | 809 | goto out; |
| 810 | |
Thomas Gleixner | 157d29e | 2015-04-14 21:08:56 +0000 | [diff] [blame] | 811 | /* |
| 812 | * nohz_stop_sched_tick can be called several times before |
| 813 | * the nohz_restart_sched_tick is called. This happens when |
| 814 | * interrupts arrive which do not cause a reschedule. In the |
| 815 | * first call we save the current tick time, so we can restart |
| 816 | * the scheduler tick in nohz_restart_sched_tick. |
| 817 | */ |
| 818 | if (!ts->tick_stopped) { |
| 819 | nohz_balance_enter_idle(cpu); |
| 820 | calc_load_enter_idle(); |
| 821 | |
| 822 | ts->last_tick = hrtimer_get_expires(&ts->sched_timer); |
| 823 | ts->tick_stopped = 1; |
| 824 | trace_tick_stop(1, " "); |
| 825 | } |
| 826 | |
| 827 | /* |
Thomas Gleixner | c1ad348 | 2015-04-14 21:08:58 +0000 | [diff] [blame] | 828 | * If the expiration time == KTIME_MAX, then we simply stop |
| 829 | * the tick timer. |
Thomas Gleixner | 157d29e | 2015-04-14 21:08:56 +0000 | [diff] [blame] | 830 | */ |
Thomas Gleixner | c1ad348 | 2015-04-14 21:08:58 +0000 | [diff] [blame] | 831 | if (unlikely(expires == KTIME_MAX)) { |
Thomas Gleixner | 157d29e | 2015-04-14 21:08:56 +0000 | [diff] [blame] | 832 | if (ts->nohz_mode == NOHZ_MODE_HIGHRES) |
| 833 | hrtimer_cancel(&ts->sched_timer); |
| 834 | goto out; |
| 835 | } |
| 836 | |
| 837 | if (ts->nohz_mode == NOHZ_MODE_HIGHRES) |
Thomas Gleixner | c1ad348 | 2015-04-14 21:08:58 +0000 | [diff] [blame] | 838 | hrtimer_start(&ts->sched_timer, tick, HRTIMER_MODE_ABS_PINNED); |
Thomas Gleixner | 157d29e | 2015-04-14 21:08:56 +0000 | [diff] [blame] | 839 | else |
Thomas Gleixner | c1ad348 | 2015-04-14 21:08:58 +0000 | [diff] [blame] | 840 | tick_program_event(tick, 1); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 841 | out: |
Thomas Gleixner | c1ad348 | 2015-04-14 21:08:58 +0000 | [diff] [blame] | 842 | /* Update the estimated sleep length */ |
Len Brown | 4f86d3a | 2007-10-03 18:58:00 -0400 | [diff] [blame] | 843 | ts->sleep_length = ktime_sub(dev->next_event, now); |
Thomas Gleixner | c1ad348 | 2015-04-14 21:08:58 +0000 | [diff] [blame] | 844 | return tick; |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 845 | } |
| 846 | |
Byungchul Park | 525705d | 2015-11-10 09:36:02 +0900 | [diff] [blame] | 847 | static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now, int active) |
Frederic Weisbecker | 59d2c7c | 2015-05-29 14:42:15 +0200 | [diff] [blame] | 848 | { |
| 849 | /* Update jiffies first */ |
| 850 | tick_do_update_jiffies64(now); |
Byungchul Park | 525705d | 2015-11-10 09:36:02 +0900 | [diff] [blame] | 851 | update_cpu_load_nohz(active); |
Frederic Weisbecker | 59d2c7c | 2015-05-29 14:42:15 +0200 | [diff] [blame] | 852 | |
| 853 | calc_load_exit_idle(); |
Tejun Heo | 03e0d46 | 2015-12-08 11:28:04 -0500 | [diff] [blame] | 854 | touch_softlockup_watchdog_sched(); |
Frederic Weisbecker | 59d2c7c | 2015-05-29 14:42:15 +0200 | [diff] [blame] | 855 | /* |
| 856 | * Cancel the scheduled timer and restore the tick |
| 857 | */ |
| 858 | ts->tick_stopped = 0; |
| 859 | ts->idle_exittime = now; |
| 860 | |
| 861 | tick_nohz_restart(ts, now); |
| 862 | } |
Frederic Weisbecker | 73738a9 | 2015-05-27 19:22:08 +0200 | [diff] [blame] | 863 | |
| 864 | static void tick_nohz_full_update_tick(struct tick_sched *ts) |
Frederic Weisbecker | 5811d99 | 2013-04-20 16:40:31 +0200 | [diff] [blame] | 865 | { |
| 866 | #ifdef CONFIG_NO_HZ_FULL |
Alex Shi | e9a2eb4 | 2013-11-28 14:27:11 +0800 | [diff] [blame] | 867 | int cpu = smp_processor_id(); |
Frederic Weisbecker | 5811d99 | 2013-04-20 16:40:31 +0200 | [diff] [blame] | 868 | |
Frederic Weisbecker | 5944935 | 2015-05-27 15:42:42 +0200 | [diff] [blame] | 869 | if (!tick_nohz_full_cpu(cpu)) |
Alex Shi | e9a2eb4 | 2013-11-28 14:27:11 +0800 | [diff] [blame] | 870 | return; |
Frederic Weisbecker | 5811d99 | 2013-04-20 16:40:31 +0200 | [diff] [blame] | 871 | |
Alex Shi | e9a2eb4 | 2013-11-28 14:27:11 +0800 | [diff] [blame] | 872 | if (!ts->tick_stopped && ts->nohz_mode == NOHZ_MODE_INACTIVE) |
| 873 | return; |
Frederic Weisbecker | 5811d99 | 2013-04-20 16:40:31 +0200 | [diff] [blame] | 874 | |
Frederic Weisbecker | d027d45 | 2015-06-07 15:54:30 +0200 | [diff] [blame^] | 875 | if (can_stop_full_tick(ts)) |
Frederic Weisbecker | 73738a9 | 2015-05-27 19:22:08 +0200 | [diff] [blame] | 876 | tick_nohz_stop_sched_tick(ts, ktime_get(), cpu); |
| 877 | else if (ts->tick_stopped) |
Byungchul Park | 525705d | 2015-11-10 09:36:02 +0900 | [diff] [blame] | 878 | tick_nohz_restart_sched_tick(ts, ktime_get(), 1); |
Frederic Weisbecker | 5811d99 | 2013-04-20 16:40:31 +0200 | [diff] [blame] | 879 | #endif |
| 880 | } |
| 881 | |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 882 | static bool can_stop_idle_tick(int cpu, struct tick_sched *ts) |
| 883 | { |
| 884 | /* |
| 885 | * If this cpu is offline and it is the one which updates |
| 886 | * jiffies, then give up the assignment and let it be taken by |
| 887 | * the cpu which runs the tick timer next. If we don't drop |
| 888 | * this here the jiffies might be stale and do_timer() never |
| 889 | * invoked. |
| 890 | */ |
| 891 | if (unlikely(!cpu_online(cpu))) { |
| 892 | if (cpu == tick_do_timer_cpu) |
| 893 | tick_do_timer_cpu = TICK_DO_TIMER_NONE; |
Thomas Gleixner | f7ea0fd | 2013-05-13 21:40:27 +0200 | [diff] [blame] | 894 | return false; |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 895 | } |
| 896 | |
Thomas Gleixner | 0e576acb | 2013-11-29 12:18:13 +0100 | [diff] [blame] | 897 | if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE)) { |
| 898 | ts->sleep_length = (ktime_t) { .tv64 = NSEC_PER_SEC/HZ }; |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 899 | return false; |
Thomas Gleixner | 0e576acb | 2013-11-29 12:18:13 +0100 | [diff] [blame] | 900 | } |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 901 | |
| 902 | if (need_resched()) |
| 903 | return false; |
| 904 | |
| 905 | if (unlikely(local_softirq_pending() && cpu_online(cpu))) { |
| 906 | static int ratelimit; |
| 907 | |
Paul E. McKenney | 803b0eb | 2012-08-23 08:34:07 -0700 | [diff] [blame] | 908 | if (ratelimit < 10 && |
| 909 | (local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK)) { |
Rado Vrbovsky | cfea7d7 | 2013-02-08 12:37:30 -0500 | [diff] [blame] | 910 | pr_warn("NOHZ: local_softirq_pending %02x\n", |
| 911 | (unsigned int) local_softirq_pending()); |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 912 | ratelimit++; |
| 913 | } |
| 914 | return false; |
| 915 | } |
| 916 | |
Frederic Weisbecker | 460775d | 2013-07-24 23:52:27 +0200 | [diff] [blame] | 917 | if (tick_nohz_full_enabled()) { |
Frederic Weisbecker | a382bf9 | 2012-12-18 18:24:35 +0100 | [diff] [blame] | 918 | /* |
| 919 | * Keep the tick alive to guarantee timekeeping progression |
| 920 | * if there are full dynticks CPUs around |
| 921 | */ |
| 922 | if (tick_do_timer_cpu == cpu) |
| 923 | return false; |
| 924 | /* |
| 925 | * Boot safety: make sure the timekeeping duty has been |
| 926 | * assigned before entering dyntick-idle mode, |
| 927 | */ |
| 928 | if (tick_do_timer_cpu == TICK_DO_TIMER_NONE) |
| 929 | return false; |
| 930 | } |
| 931 | |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 932 | return true; |
| 933 | } |
| 934 | |
Frederic Weisbecker | 19f5f73 | 2011-07-27 17:29:28 +0200 | [diff] [blame] | 935 | static void __tick_nohz_idle_enter(struct tick_sched *ts) |
| 936 | { |
Frederic Weisbecker | 84bf1bc | 2011-08-01 01:25:38 +0200 | [diff] [blame] | 937 | ktime_t now, expires; |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 938 | int cpu = smp_processor_id(); |
Frederic Weisbecker | 19f5f73 | 2011-07-27 17:29:28 +0200 | [diff] [blame] | 939 | |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 940 | now = tick_nohz_start_idle(ts); |
Frederic Weisbecker | 2ac0d98 | 2011-07-28 04:00:47 +0200 | [diff] [blame] | 941 | |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 942 | if (can_stop_idle_tick(cpu, ts)) { |
| 943 | int was_stopped = ts->tick_stopped; |
| 944 | |
| 945 | ts->idle_calls++; |
Frederic Weisbecker | 84bf1bc | 2011-08-01 01:25:38 +0200 | [diff] [blame] | 946 | |
| 947 | expires = tick_nohz_stop_sched_tick(ts, now, cpu); |
| 948 | if (expires.tv64 > 0LL) { |
| 949 | ts->idle_sleeps++; |
| 950 | ts->idle_expires = expires; |
| 951 | } |
Frederic Weisbecker | 5b39939 | 2011-08-01 00:06:10 +0200 | [diff] [blame] | 952 | |
| 953 | if (!was_stopped && ts->tick_stopped) |
| 954 | ts->idle_jiffies = ts->last_jiffies; |
| 955 | } |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 956 | } |
| 957 | |
| 958 | /** |
| 959 | * tick_nohz_idle_enter - stop the idle tick from the idle task |
| 960 | * |
| 961 | * When the next event is more than a tick into the future, stop the idle tick |
| 962 | * Called when we start the idle loop. |
Frederic Weisbecker | 2bbb681 | 2011-10-08 16:01:00 +0200 | [diff] [blame] | 963 | * |
Frederic Weisbecker | 1268fbc | 2011-11-17 18:48:14 +0100 | [diff] [blame] | 964 | * The arch is responsible of calling: |
Frederic Weisbecker | 2bbb681 | 2011-10-08 16:01:00 +0200 | [diff] [blame] | 965 | * |
| 966 | * - rcu_idle_enter() after its last use of RCU before the CPU is put |
| 967 | * to sleep. |
| 968 | * - 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] | 969 | */ |
Frederic Weisbecker | 1268fbc | 2011-11-17 18:48:14 +0100 | [diff] [blame] | 970 | void tick_nohz_idle_enter(void) |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 971 | { |
| 972 | struct tick_sched *ts; |
| 973 | |
Frederic Weisbecker | 1268fbc | 2011-11-17 18:48:14 +0100 | [diff] [blame] | 974 | WARN_ON_ONCE(irqs_disabled()); |
| 975 | |
Linus Torvalds | 0db49b7 | 2012-01-06 08:33:28 -0800 | [diff] [blame] | 976 | /* |
| 977 | * Update the idle state in the scheduler domain hierarchy |
| 978 | * when tick_nohz_stop_sched_tick() is called from the idle loop. |
| 979 | * State will be updated to busy during the first busy tick after |
| 980 | * exiting idle. |
| 981 | */ |
| 982 | set_cpu_sd_state_idle(); |
| 983 | |
Frederic Weisbecker | 1268fbc | 2011-11-17 18:48:14 +0100 | [diff] [blame] | 984 | local_irq_disable(); |
| 985 | |
Christoph Lameter | 22127e9 | 2014-08-17 12:30:25 -0500 | [diff] [blame] | 986 | ts = this_cpu_ptr(&tick_cpu_sched); |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 987 | ts->inidle = 1; |
Frederic Weisbecker | 19f5f73 | 2011-07-27 17:29:28 +0200 | [diff] [blame] | 988 | __tick_nohz_idle_enter(ts); |
Frederic Weisbecker | 1268fbc | 2011-11-17 18:48:14 +0100 | [diff] [blame] | 989 | |
| 990 | local_irq_enable(); |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 991 | } |
| 992 | |
| 993 | /** |
| 994 | * tick_nohz_irq_exit - update next tick event from interrupt exit |
| 995 | * |
| 996 | * When an interrupt fires while we are idle and it doesn't cause |
| 997 | * a reschedule, it may still add, modify or delete a timer, enqueue |
| 998 | * an RCU callback, etc... |
| 999 | * So we need to re-calculate and reprogram the next tick event. |
| 1000 | */ |
| 1001 | void tick_nohz_irq_exit(void) |
| 1002 | { |
Christoph Lameter | 22127e9 | 2014-08-17 12:30:25 -0500 | [diff] [blame] | 1003 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
Frederic Weisbecker | 280f067 | 2011-10-07 18:22:06 +0200 | [diff] [blame] | 1004 | |
Rafael J. Wysocki | 1485191 | 2013-07-27 01:41:34 +0200 | [diff] [blame] | 1005 | if (ts->inidle) |
Frederic Weisbecker | 5811d99 | 2013-04-20 16:40:31 +0200 | [diff] [blame] | 1006 | __tick_nohz_idle_enter(ts); |
Rafael J. Wysocki | 1485191 | 2013-07-27 01:41:34 +0200 | [diff] [blame] | 1007 | else |
Frederic Weisbecker | 73738a9 | 2015-05-27 19:22:08 +0200 | [diff] [blame] | 1008 | tick_nohz_full_update_tick(ts); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1009 | } |
| 1010 | |
| 1011 | /** |
Len Brown | 4f86d3a | 2007-10-03 18:58:00 -0400 | [diff] [blame] | 1012 | * tick_nohz_get_sleep_length - return the length of the current sleep |
| 1013 | * |
| 1014 | * Called from power state control code with interrupts disabled |
| 1015 | */ |
| 1016 | ktime_t tick_nohz_get_sleep_length(void) |
| 1017 | { |
Christoph Lameter | 22127e9 | 2014-08-17 12:30:25 -0500 | [diff] [blame] | 1018 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
Len Brown | 4f86d3a | 2007-10-03 18:58:00 -0400 | [diff] [blame] | 1019 | |
| 1020 | return ts->sleep_length; |
| 1021 | } |
| 1022 | |
Frederic Weisbecker | 2ac0d98 | 2011-07-28 04:00:47 +0200 | [diff] [blame] | 1023 | static void tick_nohz_account_idle_ticks(struct tick_sched *ts) |
| 1024 | { |
Frederic Weisbecker | 3f4724e | 2012-07-16 18:00:34 +0200 | [diff] [blame] | 1025 | #ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE |
Frederic Weisbecker | 2ac0d98 | 2011-07-28 04:00:47 +0200 | [diff] [blame] | 1026 | unsigned long ticks; |
Frederic Weisbecker | 3f4724e | 2012-07-16 18:00:34 +0200 | [diff] [blame] | 1027 | |
Frederic Weisbecker | 55dbdcf | 2015-11-19 16:47:32 +0100 | [diff] [blame] | 1028 | if (vtime_accounting_cpu_enabled()) |
Frederic Weisbecker | 3f4724e | 2012-07-16 18:00:34 +0200 | [diff] [blame] | 1029 | return; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1030 | /* |
| 1031 | * We stopped the tick in idle. Update process times would miss the |
| 1032 | * time we slept as update_process_times does only a 1 tick |
| 1033 | * accounting. Enforce that this is accounted to idle ! |
| 1034 | */ |
| 1035 | ticks = jiffies - ts->idle_jiffies; |
| 1036 | /* |
| 1037 | * We might be one off. Do not randomly account a huge number of ticks! |
| 1038 | */ |
Martin Schwidefsky | 79741dd | 2008-12-31 15:11:38 +0100 | [diff] [blame] | 1039 | if (ticks && ticks < LONG_MAX) |
| 1040 | account_idle_ticks(ticks); |
| 1041 | #endif |
Frederic Weisbecker | 19f5f73 | 2011-07-27 17:29:28 +0200 | [diff] [blame] | 1042 | } |
| 1043 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1044 | /** |
| 1045 | * tick_nohz_idle_exit - restart the idle tick from the idle task |
| 1046 | * |
| 1047 | * Restart the idle tick when the CPU is woken up from idle |
| 1048 | * This also exit the RCU extended quiescent state. The CPU |
| 1049 | * can use RCU again after this function is called. |
| 1050 | */ |
| 1051 | void tick_nohz_idle_exit(void) |
| 1052 | { |
Christoph Lameter | 4a32fea | 2014-08-17 12:30:27 -0500 | [diff] [blame] | 1053 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1054 | ktime_t now; |
| 1055 | |
| 1056 | local_irq_disable(); |
| 1057 | |
| 1058 | WARN_ON_ONCE(!ts->inidle); |
| 1059 | |
| 1060 | ts->inidle = 0; |
| 1061 | |
| 1062 | if (ts->idle_active || ts->tick_stopped) |
| 1063 | now = ktime_get(); |
| 1064 | |
| 1065 | if (ts->idle_active) |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 1066 | tick_nohz_stop_idle(ts, now); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1067 | |
Frederic Weisbecker | 2ac0d98 | 2011-07-28 04:00:47 +0200 | [diff] [blame] | 1068 | if (ts->tick_stopped) { |
Byungchul Park | 525705d | 2015-11-10 09:36:02 +0900 | [diff] [blame] | 1069 | tick_nohz_restart_sched_tick(ts, now, 0); |
Frederic Weisbecker | 2ac0d98 | 2011-07-28 04:00:47 +0200 | [diff] [blame] | 1070 | tick_nohz_account_idle_ticks(ts); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1071 | } |
| 1072 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1073 | local_irq_enable(); |
| 1074 | } |
| 1075 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1076 | /* |
| 1077 | * The nohz low res interrupt handler |
| 1078 | */ |
| 1079 | static void tick_nohz_handler(struct clock_event_device *dev) |
| 1080 | { |
Christoph Lameter | 22127e9 | 2014-08-17 12:30:25 -0500 | [diff] [blame] | 1081 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1082 | struct pt_regs *regs = get_irq_regs(); |
| 1083 | ktime_t now = ktime_get(); |
| 1084 | |
| 1085 | dev->next_event.tv64 = KTIME_MAX; |
| 1086 | |
Frederic Weisbecker | 5bb9622 | 2012-10-15 02:03:27 +0200 | [diff] [blame] | 1087 | tick_sched_do_timer(now); |
Frederic Weisbecker | 9e8f559 | 2012-10-15 02:43:03 +0200 | [diff] [blame] | 1088 | tick_sched_handle(ts, regs); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1089 | |
Viresh Kumar | b5e995e | 2014-06-12 16:24:41 +0530 | [diff] [blame] | 1090 | /* No need to reprogram if we are running tickless */ |
| 1091 | if (unlikely(ts->tick_stopped)) |
| 1092 | return; |
| 1093 | |
Thomas Gleixner | 0ff53d0 | 2015-04-14 21:08:54 +0000 | [diff] [blame] | 1094 | hrtimer_forward(&ts->sched_timer, now, tick_period); |
| 1095 | tick_program_event(hrtimer_get_expires(&ts->sched_timer), 1); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1096 | } |
| 1097 | |
Thomas Gleixner | bc7a34b | 2015-05-26 22:50:33 +0000 | [diff] [blame] | 1098 | static inline void tick_nohz_activate(struct tick_sched *ts, int mode) |
| 1099 | { |
| 1100 | if (!tick_nohz_enabled) |
| 1101 | return; |
| 1102 | ts->nohz_mode = mode; |
| 1103 | /* One update is enough */ |
| 1104 | if (!test_and_set_bit(0, &tick_nohz_active)) |
Thomas Gleixner | 683be13 | 2015-05-26 22:50:35 +0000 | [diff] [blame] | 1105 | timers_update_migration(true); |
Thomas Gleixner | bc7a34b | 2015-05-26 22:50:33 +0000 | [diff] [blame] | 1106 | } |
| 1107 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1108 | /** |
| 1109 | * tick_nohz_switch_to_nohz - switch to nohz mode |
| 1110 | */ |
| 1111 | static void tick_nohz_switch_to_nohz(void) |
| 1112 | { |
Christoph Lameter | 22127e9 | 2014-08-17 12:30:25 -0500 | [diff] [blame] | 1113 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1114 | ktime_t next; |
| 1115 | |
Viresh Kumar | 2763053 | 2014-04-15 10:54:41 +0530 | [diff] [blame] | 1116 | if (!tick_nohz_enabled) |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1117 | return; |
| 1118 | |
Thomas Gleixner | 6b442bc | 2015-05-07 14:35:59 +0200 | [diff] [blame] | 1119 | if (tick_switch_to_oneshot(tick_nohz_handler)) |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1120 | return; |
Thomas Gleixner | 6b442bc | 2015-05-07 14:35:59 +0200 | [diff] [blame] | 1121 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1122 | /* |
| 1123 | * Recycle the hrtimer in ts, so we can share the |
| 1124 | * hrtimer_forward with the highres code. |
| 1125 | */ |
| 1126 | hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); |
| 1127 | /* Get the next period */ |
| 1128 | next = tick_init_jiffy_update(); |
| 1129 | |
Thomas Gleixner | 0ff53d0 | 2015-04-14 21:08:54 +0000 | [diff] [blame] | 1130 | hrtimer_set_expires(&ts->sched_timer, next); |
Wanpeng Li | 1ca8ec5 | 2016-01-27 19:26:07 +0800 | [diff] [blame] | 1131 | hrtimer_forward_now(&ts->sched_timer, tick_period); |
| 1132 | tick_program_event(hrtimer_get_expires(&ts->sched_timer), 1); |
Thomas Gleixner | bc7a34b | 2015-05-26 22:50:33 +0000 | [diff] [blame] | 1133 | tick_nohz_activate(ts, NOHZ_MODE_LOWRES); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1134 | } |
| 1135 | |
Thomas Gleixner | fb02fbc | 2008-10-17 10:01:23 +0200 | [diff] [blame] | 1136 | /* |
| 1137 | * When NOHZ is enabled and the tick is stopped, we need to kick the |
| 1138 | * tick timer from irq_enter() so that the jiffies update is kept |
| 1139 | * alive during long running softirqs. That's ugly as hell, but |
| 1140 | * correctness is key even if we need to fix the offending softirq in |
| 1141 | * the first place. |
| 1142 | * |
| 1143 | * Note, this is different to tick_nohz_restart. We just kick the |
| 1144 | * timer and do not touch the other magic bits which need to be done |
| 1145 | * when idle is left. |
| 1146 | */ |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 1147 | 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] | 1148 | { |
Thomas Gleixner | ae99286 | 2008-11-10 13:20:23 +0100 | [diff] [blame] | 1149 | #if 0 |
| 1150 | /* Switch back to 2.6.27 behaviour */ |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 1151 | ktime_t delta; |
Thomas Gleixner | fb02fbc | 2008-10-17 10:01:23 +0200 | [diff] [blame] | 1152 | |
Thomas Gleixner | c4bd822 | 2008-10-21 20:17:35 +0200 | [diff] [blame] | 1153 | /* |
| 1154 | * Do not touch the tick device, when the next expiry is either |
| 1155 | * already reached or less/equal than the tick period. |
| 1156 | */ |
Thomas Gleixner | 268a3dc | 2008-10-22 09:48:06 +0200 | [diff] [blame] | 1157 | delta = ktime_sub(hrtimer_get_expires(&ts->sched_timer), now); |
Thomas Gleixner | c4bd822 | 2008-10-21 20:17:35 +0200 | [diff] [blame] | 1158 | if (delta.tv64 <= tick_period.tv64) |
| 1159 | return; |
| 1160 | |
| 1161 | tick_nohz_restart(ts, now); |
Thomas Gleixner | ae99286 | 2008-11-10 13:20:23 +0100 | [diff] [blame] | 1162 | #endif |
Thomas Gleixner | fb02fbc | 2008-10-17 10:01:23 +0200 | [diff] [blame] | 1163 | } |
| 1164 | |
Frederic Weisbecker | 5acac1b | 2013-12-04 18:28:20 +0100 | [diff] [blame] | 1165 | static inline void tick_nohz_irq_enter(void) |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 1166 | { |
Christoph Lameter | 4a32fea | 2014-08-17 12:30:27 -0500 | [diff] [blame] | 1167 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 1168 | ktime_t now; |
| 1169 | |
| 1170 | if (!ts->idle_active && !ts->tick_stopped) |
| 1171 | return; |
| 1172 | now = ktime_get(); |
| 1173 | if (ts->idle_active) |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 1174 | tick_nohz_stop_idle(ts, now); |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 1175 | if (ts->tick_stopped) { |
| 1176 | tick_nohz_update_jiffies(now); |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 1177 | tick_nohz_kick_tick(ts, now); |
Martin Schwidefsky | eed3b9c | 2009-09-29 14:25:15 +0200 | [diff] [blame] | 1178 | } |
| 1179 | } |
| 1180 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1181 | #else |
| 1182 | |
| 1183 | static inline void tick_nohz_switch_to_nohz(void) { } |
Frederic Weisbecker | 5acac1b | 2013-12-04 18:28:20 +0100 | [diff] [blame] | 1184 | static inline void tick_nohz_irq_enter(void) { } |
Thomas Gleixner | bc7a34b | 2015-05-26 22:50:33 +0000 | [diff] [blame] | 1185 | static inline void tick_nohz_activate(struct tick_sched *ts, int mode) { } |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1186 | |
Frederic Weisbecker | 3451d02 | 2011-08-10 23:21:01 +0200 | [diff] [blame] | 1187 | #endif /* CONFIG_NO_HZ_COMMON */ |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1188 | |
| 1189 | /* |
Thomas Gleixner | 719254f | 2008-10-17 09:59:47 +0200 | [diff] [blame] | 1190 | * Called from irq_enter to notify about the possible interruption of idle() |
| 1191 | */ |
Frederic Weisbecker | 5acac1b | 2013-12-04 18:28:20 +0100 | [diff] [blame] | 1192 | void tick_irq_enter(void) |
Thomas Gleixner | 719254f | 2008-10-17 09:59:47 +0200 | [diff] [blame] | 1193 | { |
Frederic Weisbecker | e8fcaa5 | 2013-08-07 22:28:01 +0200 | [diff] [blame] | 1194 | tick_check_oneshot_broadcast_this_cpu(); |
Frederic Weisbecker | 5acac1b | 2013-12-04 18:28:20 +0100 | [diff] [blame] | 1195 | tick_nohz_irq_enter(); |
Thomas Gleixner | 719254f | 2008-10-17 09:59:47 +0200 | [diff] [blame] | 1196 | } |
| 1197 | |
| 1198 | /* |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1199 | * High resolution timer specific code |
| 1200 | */ |
| 1201 | #ifdef CONFIG_HIGH_RES_TIMERS |
| 1202 | /* |
Pavel Machek | 4c9dc64 | 2008-01-30 13:30:00 +0100 | [diff] [blame] | 1203 | * We rearm the timer until we get disabled by the idle code. |
Chuansheng Liu | 351f181 | 2012-10-25 01:07:35 +0800 | [diff] [blame] | 1204 | * Called with interrupts disabled. |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1205 | */ |
| 1206 | static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer) |
| 1207 | { |
| 1208 | struct tick_sched *ts = |
| 1209 | container_of(timer, struct tick_sched, sched_timer); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1210 | struct pt_regs *regs = get_irq_regs(); |
| 1211 | ktime_t now = ktime_get(); |
Thomas Gleixner | d3ed782 | 2007-05-08 00:30:03 -0700 | [diff] [blame] | 1212 | |
Frederic Weisbecker | 5bb9622 | 2012-10-15 02:03:27 +0200 | [diff] [blame] | 1213 | tick_sched_do_timer(now); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1214 | |
| 1215 | /* |
| 1216 | * Do not call, when we are not in irq context and have |
| 1217 | * no valid regs pointer |
| 1218 | */ |
Frederic Weisbecker | 9e8f559 | 2012-10-15 02:43:03 +0200 | [diff] [blame] | 1219 | if (regs) |
| 1220 | tick_sched_handle(ts, regs); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1221 | |
Viresh Kumar | 2a16fc9 | 2014-06-12 16:24:41 +0530 | [diff] [blame] | 1222 | /* No need to reprogram if we are in idle or full dynticks mode */ |
| 1223 | if (unlikely(ts->tick_stopped)) |
| 1224 | return HRTIMER_NORESTART; |
| 1225 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1226 | hrtimer_forward(timer, now, tick_period); |
| 1227 | |
| 1228 | return HRTIMER_RESTART; |
| 1229 | } |
| 1230 | |
Mike Galbraith | 5307c95 | 2012-05-08 12:20:58 +0200 | [diff] [blame] | 1231 | static int sched_skew_tick; |
| 1232 | |
Thomas Gleixner | 62cf20b | 2012-05-25 14:08:57 +0200 | [diff] [blame] | 1233 | static int __init skew_tick(char *str) |
| 1234 | { |
| 1235 | get_option(&str, &sched_skew_tick); |
| 1236 | |
| 1237 | return 0; |
| 1238 | } |
| 1239 | early_param("skew_tick", skew_tick); |
| 1240 | |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1241 | /** |
| 1242 | * tick_setup_sched_timer - setup the tick emulation timer |
| 1243 | */ |
| 1244 | void tick_setup_sched_timer(void) |
| 1245 | { |
Christoph Lameter | 22127e9 | 2014-08-17 12:30:25 -0500 | [diff] [blame] | 1246 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1247 | ktime_t now = ktime_get(); |
| 1248 | |
| 1249 | /* |
| 1250 | * Emulate tick processing via per-CPU hrtimers: |
| 1251 | */ |
| 1252 | hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); |
| 1253 | ts->sched_timer.function = tick_sched_timer; |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1254 | |
john stultz | 3704540 | 2007-07-21 04:37:35 -0700 | [diff] [blame] | 1255 | /* Get the next period (per cpu) */ |
Arjan van de Ven | cc584b2 | 2008-09-01 15:02:30 -0700 | [diff] [blame] | 1256 | hrtimer_set_expires(&ts->sched_timer, tick_init_jiffy_update()); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1257 | |
Thomas Gleixner | 9c3f9e2 | 2012-11-21 20:31:52 +0100 | [diff] [blame] | 1258 | /* Offset the tick to avert jiffies_lock contention. */ |
Mike Galbraith | 5307c95 | 2012-05-08 12:20:58 +0200 | [diff] [blame] | 1259 | if (sched_skew_tick) { |
| 1260 | u64 offset = ktime_to_ns(tick_period) >> 1; |
| 1261 | do_div(offset, num_possible_cpus()); |
| 1262 | offset *= smp_processor_id(); |
| 1263 | hrtimer_add_expires_ns(&ts->sched_timer, offset); |
| 1264 | } |
| 1265 | |
Thomas Gleixner | afc08b1 | 2015-04-14 21:08:52 +0000 | [diff] [blame] | 1266 | hrtimer_forward(&ts->sched_timer, now, tick_period); |
| 1267 | hrtimer_start_expires(&ts->sched_timer, HRTIMER_MODE_ABS_PINNED); |
Thomas Gleixner | bc7a34b | 2015-05-26 22:50:33 +0000 | [diff] [blame] | 1268 | tick_nohz_activate(ts, NOHZ_MODE_HIGHRES); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1269 | } |
Miao Xie | 3c4fbe5 | 2008-08-20 16:37:38 -0700 | [diff] [blame] | 1270 | #endif /* HIGH_RES_TIMERS */ |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1271 | |
Frederic Weisbecker | 3451d02 | 2011-08-10 23:21:01 +0200 | [diff] [blame] | 1272 | #if defined CONFIG_NO_HZ_COMMON || defined CONFIG_HIGH_RES_TIMERS |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1273 | void tick_cancel_sched_timer(int cpu) |
| 1274 | { |
| 1275 | struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); |
| 1276 | |
Miao Xie | 3c4fbe5 | 2008-08-20 16:37:38 -0700 | [diff] [blame] | 1277 | # ifdef CONFIG_HIGH_RES_TIMERS |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1278 | if (ts->sched_timer.base) |
| 1279 | hrtimer_cancel(&ts->sched_timer); |
Miao Xie | 3c4fbe5 | 2008-08-20 16:37:38 -0700 | [diff] [blame] | 1280 | # endif |
Karsten Wiese | a790176 | 2008-03-04 14:59:55 -0800 | [diff] [blame] | 1281 | |
Thomas Gleixner | 4b0c0f2 | 2013-05-03 15:02:50 +0200 | [diff] [blame] | 1282 | memset(ts, 0, sizeof(*ts)); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1283 | } |
Miao Xie | 3c4fbe5 | 2008-08-20 16:37:38 -0700 | [diff] [blame] | 1284 | #endif |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1285 | |
| 1286 | /** |
| 1287 | * Async notification about clocksource changes |
| 1288 | */ |
| 1289 | void tick_clock_notify(void) |
| 1290 | { |
| 1291 | int cpu; |
| 1292 | |
| 1293 | for_each_possible_cpu(cpu) |
| 1294 | set_bit(0, &per_cpu(tick_cpu_sched, cpu).check_clocks); |
| 1295 | } |
| 1296 | |
| 1297 | /* |
| 1298 | * Async notification about clock event changes |
| 1299 | */ |
| 1300 | void tick_oneshot_notify(void) |
| 1301 | { |
Christoph Lameter | 22127e9 | 2014-08-17 12:30:25 -0500 | [diff] [blame] | 1302 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1303 | |
| 1304 | set_bit(0, &ts->check_clocks); |
| 1305 | } |
| 1306 | |
| 1307 | /** |
| 1308 | * Check, if a change happened, which makes oneshot possible. |
| 1309 | * |
| 1310 | * Called cyclic from the hrtimer softirq (driven by the timer |
| 1311 | * softirq) allow_nohz signals, that we can switch into low-res nohz |
| 1312 | * mode, because high resolution timers are disabled (either compile |
Thomas Gleixner | 6b442bc | 2015-05-07 14:35:59 +0200 | [diff] [blame] | 1313 | * or runtime). Called with interrupts disabled. |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1314 | */ |
| 1315 | int tick_check_oneshot_change(int allow_nohz) |
| 1316 | { |
Christoph Lameter | 22127e9 | 2014-08-17 12:30:25 -0500 | [diff] [blame] | 1317 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1318 | |
| 1319 | if (!test_and_clear_bit(0, &ts->check_clocks)) |
| 1320 | return 0; |
| 1321 | |
| 1322 | if (ts->nohz_mode != NOHZ_MODE_INACTIVE) |
| 1323 | return 0; |
| 1324 | |
Li Zefan | cf4fc6c | 2008-02-08 04:19:24 -0800 | [diff] [blame] | 1325 | if (!timekeeping_valid_for_hres() || !tick_is_oneshot_available()) |
Thomas Gleixner | 79bf2bb | 2007-02-16 01:28:03 -0800 | [diff] [blame] | 1326 | return 0; |
| 1327 | |
| 1328 | if (!allow_nohz) |
| 1329 | return 1; |
| 1330 | |
| 1331 | tick_nohz_switch_to_nohz(); |
| 1332 | return 0; |
| 1333 | } |