]>
Commit | Line | Data |
---|---|---|
79bf2bb3 TG |
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 | * | |
b10db7f0 | 12 | * Distribute under GPLv2. |
79bf2bb3 TG |
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> | |
8083e4ad | 22 | #include <linux/module.h> |
00b42959 | 23 | #include <linux/irq_work.h> |
9014c45d FW |
24 | #include <linux/posix-timers.h> |
25 | #include <linux/perf_event.h> | |
2e709338 | 26 | #include <linux/context_tracking.h> |
79bf2bb3 | 27 | |
9e203bcc DM |
28 | #include <asm/irq_regs.h> |
29 | ||
79bf2bb3 TG |
30 | #include "tick-internal.h" |
31 | ||
cb41a290 FW |
32 | #include <trace/events/timer.h> |
33 | ||
79bf2bb3 TG |
34 | /* |
35 | * Per cpu nohz control structure | |
36 | */ | |
c1797baf | 37 | static DEFINE_PER_CPU(struct tick_sched, tick_cpu_sched); |
79bf2bb3 | 38 | |
289f480a IM |
39 | struct tick_sched *tick_get_tick_sched(int cpu) |
40 | { | |
41 | return &per_cpu(tick_cpu_sched, cpu); | |
42 | } | |
43 | ||
7809998a AB |
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 | ||
79bf2bb3 TG |
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 | ||
7a14ce1d | 58 | /* |
d6ad4187 | 59 | * Do a quick check without holding jiffies_lock: |
7a14ce1d IM |
60 | */ |
61 | delta = ktime_sub(now, last_jiffies_update); | |
62 | if (delta.tv64 < tick_period.tv64) | |
63 | return; | |
64 | ||
d6ad4187 JS |
65 | /* Reevalute with jiffies_lock held */ |
66 | write_seqlock(&jiffies_lock); | |
79bf2bb3 TG |
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); | |
49d670fb TG |
85 | |
86 | /* Keep the tick_next_period variable up to date */ | |
87 | tick_next_period = ktime_add(last_jiffies_update, tick_period); | |
03e6bdc5 VK |
88 | } else { |
89 | write_sequnlock(&jiffies_lock); | |
90 | return; | |
79bf2bb3 | 91 | } |
d6ad4187 | 92 | write_sequnlock(&jiffies_lock); |
47a1b796 | 93 | update_wall_time(); |
79bf2bb3 TG |
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 | ||
d6ad4187 | 103 | write_seqlock(&jiffies_lock); |
79bf2bb3 TG |
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; | |
d6ad4187 | 108 | write_sequnlock(&jiffies_lock); |
79bf2bb3 TG |
109 | return period; |
110 | } | |
111 | ||
5bb96226 FW |
112 | |
113 | static void tick_sched_do_timer(ktime_t now) | |
114 | { | |
115 | int cpu = smp_processor_id(); | |
116 | ||
3451d024 | 117 | #ifdef CONFIG_NO_HZ_COMMON |
5bb96226 FW |
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 | |
9c3f9e28 | 123 | * jiffies_lock. |
5bb96226 | 124 | */ |
a382bf93 | 125 | if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE) |
c5bfece2 | 126 | && !tick_nohz_full_cpu(cpu)) |
5bb96226 FW |
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 | ||
9e8f559b FW |
135 | static void tick_sched_handle(struct tick_sched *ts, struct pt_regs *regs) |
136 | { | |
3451d024 | 137 | #ifdef CONFIG_NO_HZ_COMMON |
9e8f559b FW |
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) { | |
03e0d461 | 147 | touch_softlockup_watchdog_sched(); |
9e8f559b FW |
148 | if (is_idle_task(current)) |
149 | ts->idle_jiffies++; | |
150 | } | |
94a57140 | 151 | #endif |
9e8f559b FW |
152 | update_process_times(user_mode(regs)); |
153 | profile_tick(CPU_PROFILING); | |
154 | } | |
7809998a | 155 | #endif |
9e8f559b | 156 | |
c5bfece2 | 157 | #ifdef CONFIG_NO_HZ_FULL |
460775df | 158 | cpumask_var_t tick_nohz_full_mask; |
c0f489d2 | 159 | cpumask_var_t housekeeping_mask; |
73867dcd | 160 | bool tick_nohz_full_running; |
a831881b | 161 | |
9014c45d FW |
162 | static bool can_stop_full_tick(void) |
163 | { | |
164 | WARN_ON_ONCE(!irqs_disabled()); | |
165 | ||
cb41a290 FW |
166 | if (!sched_can_stop_tick()) { |
167 | trace_tick_stop(0, "more than 1 task in runqueue\n"); | |
9014c45d | 168 | return false; |
cb41a290 | 169 | } |
9014c45d | 170 | |
cb41a290 FW |
171 | if (!posix_cpu_timers_can_stop_tick(current)) { |
172 | trace_tick_stop(0, "posix timers running\n"); | |
9014c45d | 173 | return false; |
cb41a290 | 174 | } |
9014c45d | 175 | |
cb41a290 FW |
176 | if (!perf_event_can_stop_tick()) { |
177 | trace_tick_stop(0, "perf events running\n"); | |
9014c45d | 178 | return false; |
cb41a290 | 179 | } |
9014c45d FW |
180 | |
181 | /* sched_clock_tick() needs us? */ | |
182 | #ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK | |
183 | /* | |
184 | * TODO: kick full dynticks CPUs when | |
185 | * sched_clock_stable is set. | |
186 | */ | |
35af99e6 | 187 | if (!sched_clock_stable()) { |
cb41a290 | 188 | trace_tick_stop(0, "unstable sched clock\n"); |
e12d0271 SR |
189 | /* |
190 | * Don't allow the user to think they can get | |
191 | * full NO_HZ with this machine. | |
192 | */ | |
73867dcd | 193 | WARN_ONCE(tick_nohz_full_running, |
543487c7 | 194 | "NO_HZ FULL will not work with unstable sched clock"); |
9014c45d | 195 | return false; |
cb41a290 | 196 | } |
9014c45d FW |
197 | #endif |
198 | ||
199 | return true; | |
200 | } | |
201 | ||
76c24fb0 FW |
202 | static void nohz_full_kick_work_func(struct irq_work *work) |
203 | { | |
73738a95 | 204 | /* Empty, the tick restart happens on tick_nohz_irq_exit() */ |
76c24fb0 FW |
205 | } |
206 | ||
207 | static DEFINE_PER_CPU(struct irq_work, nohz_full_kick_work) = { | |
208 | .func = nohz_full_kick_work_func, | |
209 | }; | |
210 | ||
40bea039 FW |
211 | /* |
212 | * Kick this CPU if it's full dynticks in order to force it to | |
213 | * re-evaluate its dependency on the tick and restart it if necessary. | |
214 | * This kick, unlike tick_nohz_full_kick_cpu() and tick_nohz_full_kick_all(), | |
215 | * is NMI safe. | |
216 | */ | |
217 | void tick_nohz_full_kick(void) | |
218 | { | |
219 | if (!tick_nohz_full_cpu(smp_processor_id())) | |
220 | return; | |
221 | ||
56e4dea8 | 222 | irq_work_queue(this_cpu_ptr(&nohz_full_kick_work)); |
40bea039 FW |
223 | } |
224 | ||
76c24fb0 | 225 | /* |
3d36aebc | 226 | * Kick the CPU if it's full dynticks in order to force it to |
76c24fb0 FW |
227 | * re-evaluate its dependency on the tick and restart it if necessary. |
228 | */ | |
3d36aebc | 229 | void tick_nohz_full_kick_cpu(int cpu) |
76c24fb0 | 230 | { |
3d36aebc FW |
231 | if (!tick_nohz_full_cpu(cpu)) |
232 | return; | |
233 | ||
234 | irq_work_queue_on(&per_cpu(nohz_full_kick_work, cpu), cpu); | |
76c24fb0 FW |
235 | } |
236 | ||
237 | static void nohz_full_kick_ipi(void *info) | |
238 | { | |
73738a95 | 239 | /* Empty, the tick restart happens on tick_nohz_irq_exit() */ |
76c24fb0 FW |
240 | } |
241 | ||
242 | /* | |
243 | * Kick all full dynticks CPUs in order to force these to re-evaluate | |
244 | * their dependency on the tick and restart it if necessary. | |
245 | */ | |
246 | void tick_nohz_full_kick_all(void) | |
247 | { | |
73867dcd | 248 | if (!tick_nohz_full_running) |
76c24fb0 FW |
249 | return; |
250 | ||
251 | preempt_disable(); | |
73867dcd | 252 | smp_call_function_many(tick_nohz_full_mask, |
76c24fb0 | 253 | nohz_full_kick_ipi, NULL, false); |
c2e7fcf5 | 254 | tick_nohz_full_kick(); |
76c24fb0 FW |
255 | preempt_enable(); |
256 | } | |
257 | ||
99e5ada9 FW |
258 | /* |
259 | * Re-evaluate the need for the tick as we switch the current task. | |
260 | * It might need the tick due to per task/process properties: | |
261 | * perf events, posix cpu timers, ... | |
262 | */ | |
de734f89 | 263 | void __tick_nohz_task_switch(void) |
99e5ada9 FW |
264 | { |
265 | unsigned long flags; | |
266 | ||
99e5ada9 FW |
267 | local_irq_save(flags); |
268 | ||
6296ace4 LZ |
269 | if (!tick_nohz_full_cpu(smp_processor_id())) |
270 | goto out; | |
271 | ||
99e5ada9 FW |
272 | if (tick_nohz_tick_stopped() && !can_stop_full_tick()) |
273 | tick_nohz_full_kick(); | |
274 | ||
6296ace4 | 275 | out: |
99e5ada9 FW |
276 | local_irq_restore(flags); |
277 | } | |
278 | ||
a831881b | 279 | /* Parse the boot-time nohz CPU list from the kernel parameters. */ |
c5bfece2 | 280 | static int __init tick_nohz_full_setup(char *str) |
a831881b | 281 | { |
73867dcd FW |
282 | alloc_bootmem_cpumask_var(&tick_nohz_full_mask); |
283 | if (cpulist_parse(str, tick_nohz_full_mask) < 0) { | |
c5bfece2 | 284 | pr_warning("NOHZ: Incorrect nohz_full cpumask\n"); |
4327b15f | 285 | free_bootmem_cpumask_var(tick_nohz_full_mask); |
0453b435 FW |
286 | return 1; |
287 | } | |
73867dcd | 288 | tick_nohz_full_running = true; |
0453b435 | 289 | |
a831881b FW |
290 | return 1; |
291 | } | |
c5bfece2 | 292 | __setup("nohz_full=", tick_nohz_full_setup); |
a831881b | 293 | |
0db0628d | 294 | static int tick_nohz_cpu_down_callback(struct notifier_block *nfb, |
7c8bb6cb FW |
295 | unsigned long action, |
296 | void *hcpu) | |
a382bf93 FW |
297 | { |
298 | unsigned int cpu = (unsigned long)hcpu; | |
299 | ||
300 | switch (action & ~CPU_TASKS_FROZEN) { | |
301 | case CPU_DOWN_PREPARE: | |
302 | /* | |
7c8bb6cb FW |
303 | * The boot CPU handles housekeeping duty (unbound timers, |
304 | * workqueues, timekeeping, ...) on behalf of full dynticks | |
305 | * CPUs. It must remain online when nohz full is enabled. | |
a382bf93 | 306 | */ |
73867dcd | 307 | if (tick_nohz_full_running && tick_do_timer_cpu == cpu) |
1a7f829f | 308 | return NOTIFY_BAD; |
a382bf93 FW |
309 | break; |
310 | } | |
311 | return NOTIFY_OK; | |
312 | } | |
313 | ||
f98823ac FW |
314 | static int tick_nohz_init_all(void) |
315 | { | |
316 | int err = -1; | |
317 | ||
318 | #ifdef CONFIG_NO_HZ_FULL_ALL | |
73867dcd | 319 | if (!alloc_cpumask_var(&tick_nohz_full_mask, GFP_KERNEL)) { |
4327b15f | 320 | WARN(1, "NO_HZ: Can't allocate full dynticks cpumask\n"); |
c0f489d2 PM |
321 | return err; |
322 | } | |
f98823ac | 323 | err = 0; |
73867dcd | 324 | cpumask_setall(tick_nohz_full_mask); |
73867dcd | 325 | tick_nohz_full_running = true; |
f98823ac FW |
326 | #endif |
327 | return err; | |
328 | } | |
329 | ||
d1e43fa5 | 330 | void __init tick_nohz_init(void) |
a831881b | 331 | { |
d1e43fa5 FW |
332 | int cpu; |
333 | ||
73867dcd | 334 | if (!tick_nohz_full_running) { |
f98823ac FW |
335 | if (tick_nohz_init_all() < 0) |
336 | return; | |
337 | } | |
d1e43fa5 | 338 | |
4327b15f FW |
339 | if (!alloc_cpumask_var(&housekeeping_mask, GFP_KERNEL)) { |
340 | WARN(1, "NO_HZ: Can't allocate not-full dynticks cpumask\n"); | |
341 | cpumask_clear(tick_nohz_full_mask); | |
342 | tick_nohz_full_running = false; | |
343 | return; | |
344 | } | |
345 | ||
9b01f5bf FW |
346 | /* |
347 | * Full dynticks uses irq work to drive the tick rescheduling on safe | |
348 | * locking contexts. But then we need irq work to raise its own | |
349 | * interrupts to avoid circular dependency on the tick | |
350 | */ | |
351 | if (!arch_irq_work_has_interrupt()) { | |
352 | pr_warning("NO_HZ: Can't run full dynticks because arch doesn't " | |
353 | "support irq work self-IPIs\n"); | |
354 | cpumask_clear(tick_nohz_full_mask); | |
355 | cpumask_copy(housekeeping_mask, cpu_possible_mask); | |
356 | tick_nohz_full_running = false; | |
357 | return; | |
358 | } | |
359 | ||
4327b15f FW |
360 | cpu = smp_processor_id(); |
361 | ||
362 | if (cpumask_test_cpu(cpu, tick_nohz_full_mask)) { | |
363 | pr_warning("NO_HZ: Clearing %d from nohz_full range for timekeeping\n", cpu); | |
364 | cpumask_clear_cpu(cpu, tick_nohz_full_mask); | |
365 | } | |
366 | ||
367 | cpumask_andnot(housekeeping_mask, | |
368 | cpu_possible_mask, tick_nohz_full_mask); | |
369 | ||
73867dcd | 370 | for_each_cpu(cpu, tick_nohz_full_mask) |
2e709338 FW |
371 | context_tracking_cpu_set(cpu); |
372 | ||
d1e43fa5 | 373 | cpu_notifier(tick_nohz_cpu_down_callback, 0); |
ffda22c1 TH |
374 | pr_info("NO_HZ: Full dynticks CPUs: %*pbl.\n", |
375 | cpumask_pr_args(tick_nohz_full_mask)); | |
7c8bb6cb FW |
376 | |
377 | /* | |
378 | * We need at least one CPU to handle housekeeping work such | |
379 | * as timekeeping, unbound timers, workqueues, ... | |
380 | */ | |
381 | WARN_ON_ONCE(cpumask_empty(housekeeping_mask)); | |
a831881b | 382 | } |
a831881b FW |
383 | #endif |
384 | ||
79bf2bb3 TG |
385 | /* |
386 | * NOHZ - aka dynamic tick functionality | |
387 | */ | |
3451d024 | 388 | #ifdef CONFIG_NO_HZ_COMMON |
79bf2bb3 TG |
389 | /* |
390 | * NO HZ enabled ? | |
391 | */ | |
46373a15 | 392 | int tick_nohz_enabled __read_mostly = 1; |
bc7a34b8 | 393 | unsigned long tick_nohz_active __read_mostly; |
79bf2bb3 TG |
394 | /* |
395 | * Enable / Disable tickless mode | |
396 | */ | |
397 | static int __init setup_tick_nohz(char *str) | |
398 | { | |
399 | if (!strcmp(str, "off")) | |
400 | tick_nohz_enabled = 0; | |
401 | else if (!strcmp(str, "on")) | |
402 | tick_nohz_enabled = 1; | |
403 | else | |
404 | return 0; | |
405 | return 1; | |
406 | } | |
407 | ||
408 | __setup("nohz=", setup_tick_nohz); | |
409 | ||
c1797baf TG |
410 | int tick_nohz_tick_stopped(void) |
411 | { | |
412 | return __this_cpu_read(tick_cpu_sched.tick_stopped); | |
413 | } | |
414 | ||
79bf2bb3 TG |
415 | /** |
416 | * tick_nohz_update_jiffies - update jiffies when idle was interrupted | |
417 | * | |
418 | * Called from interrupt entry when the CPU was idle | |
419 | * | |
420 | * In case the sched_tick was stopped on this CPU, we have to check if jiffies | |
421 | * must be updated. Otherwise an interrupt handler could use a stale jiffy | |
422 | * value. We do this unconditionally on any cpu, as we don't know whether the | |
423 | * cpu, which has the update task assigned is in a long sleep. | |
424 | */ | |
eed3b9cf | 425 | static void tick_nohz_update_jiffies(ktime_t now) |
79bf2bb3 | 426 | { |
79bf2bb3 | 427 | unsigned long flags; |
79bf2bb3 | 428 | |
e8fcaa5c | 429 | __this_cpu_write(tick_cpu_sched.idle_waketime, now); |
79bf2bb3 TG |
430 | |
431 | local_irq_save(flags); | |
432 | tick_do_update_jiffies64(now); | |
433 | local_irq_restore(flags); | |
02ff3755 | 434 | |
03e0d461 | 435 | touch_softlockup_watchdog_sched(); |
79bf2bb3 TG |
436 | } |
437 | ||
595aac48 AV |
438 | /* |
439 | * Updates the per cpu time idle statistics counters | |
440 | */ | |
8d63bf94 | 441 | static void |
8c215bd3 | 442 | update_ts_time_stats(int cpu, struct tick_sched *ts, ktime_t now, u64 *last_update_time) |
6378ddb5 | 443 | { |
eed3b9cf | 444 | ktime_t delta; |
6378ddb5 | 445 | |
595aac48 AV |
446 | if (ts->idle_active) { |
447 | delta = ktime_sub(now, ts->idle_entrytime); | |
8c215bd3 | 448 | if (nr_iowait_cpu(cpu) > 0) |
0224cf4c | 449 | ts->iowait_sleeptime = ktime_add(ts->iowait_sleeptime, delta); |
6beea0cd MH |
450 | else |
451 | ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta); | |
8c7b09f4 | 452 | ts->idle_entrytime = now; |
595aac48 | 453 | } |
8d63bf94 | 454 | |
e0e37c20 | 455 | if (last_update_time) |
8d63bf94 AV |
456 | *last_update_time = ktime_to_us(now); |
457 | ||
595aac48 AV |
458 | } |
459 | ||
e8fcaa5c | 460 | static void tick_nohz_stop_idle(struct tick_sched *ts, ktime_t now) |
595aac48 | 461 | { |
e8fcaa5c | 462 | update_ts_time_stats(smp_processor_id(), ts, now, NULL); |
eed3b9cf | 463 | ts->idle_active = 0; |
56c7426b | 464 | |
eed3b9cf | 465 | sched_clock_idle_wakeup_event(0); |
6378ddb5 VP |
466 | } |
467 | ||
e8fcaa5c | 468 | static ktime_t tick_nohz_start_idle(struct tick_sched *ts) |
6378ddb5 | 469 | { |
430ee881 | 470 | ktime_t now = ktime_get(); |
595aac48 | 471 | |
6378ddb5 VP |
472 | ts->idle_entrytime = now; |
473 | ts->idle_active = 1; | |
56c7426b | 474 | sched_clock_idle_sleep_event(); |
6378ddb5 VP |
475 | return now; |
476 | } | |
477 | ||
b1f724c3 AV |
478 | /** |
479 | * get_cpu_idle_time_us - get the total idle time of a cpu | |
480 | * @cpu: CPU number to query | |
09a1d34f MH |
481 | * @last_update_time: variable to store update time in. Do not update |
482 | * counters if NULL. | |
b1f724c3 AV |
483 | * |
484 | * Return the cummulative idle time (since boot) for a given | |
6beea0cd | 485 | * CPU, in microseconds. |
b1f724c3 AV |
486 | * |
487 | * This time is measured via accounting rather than sampling, | |
488 | * and is as accurate as ktime_get() is. | |
489 | * | |
490 | * This function returns -1 if NOHZ is not enabled. | |
491 | */ | |
6378ddb5 VP |
492 | u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time) |
493 | { | |
494 | struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); | |
09a1d34f | 495 | ktime_t now, idle; |
6378ddb5 | 496 | |
d689fe22 | 497 | if (!tick_nohz_active) |
8083e4ad | 498 | return -1; |
499 | ||
09a1d34f MH |
500 | now = ktime_get(); |
501 | if (last_update_time) { | |
502 | update_ts_time_stats(cpu, ts, now, last_update_time); | |
503 | idle = ts->idle_sleeptime; | |
504 | } else { | |
505 | if (ts->idle_active && !nr_iowait_cpu(cpu)) { | |
506 | ktime_t delta = ktime_sub(now, ts->idle_entrytime); | |
507 | ||
508 | idle = ktime_add(ts->idle_sleeptime, delta); | |
509 | } else { | |
510 | idle = ts->idle_sleeptime; | |
511 | } | |
512 | } | |
513 | ||
514 | return ktime_to_us(idle); | |
8083e4ad | 515 | |
6378ddb5 | 516 | } |
8083e4ad | 517 | EXPORT_SYMBOL_GPL(get_cpu_idle_time_us); |
6378ddb5 | 518 | |
6beea0cd | 519 | /** |
0224cf4c AV |
520 | * get_cpu_iowait_time_us - get the total iowait time of a cpu |
521 | * @cpu: CPU number to query | |
09a1d34f MH |
522 | * @last_update_time: variable to store update time in. Do not update |
523 | * counters if NULL. | |
0224cf4c AV |
524 | * |
525 | * Return the cummulative iowait time (since boot) for a given | |
526 | * CPU, in microseconds. | |
527 | * | |
528 | * This time is measured via accounting rather than sampling, | |
529 | * and is as accurate as ktime_get() is. | |
530 | * | |
531 | * This function returns -1 if NOHZ is not enabled. | |
532 | */ | |
533 | u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time) | |
534 | { | |
535 | struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); | |
09a1d34f | 536 | ktime_t now, iowait; |
0224cf4c | 537 | |
d689fe22 | 538 | if (!tick_nohz_active) |
0224cf4c AV |
539 | return -1; |
540 | ||
09a1d34f MH |
541 | now = ktime_get(); |
542 | if (last_update_time) { | |
543 | update_ts_time_stats(cpu, ts, now, last_update_time); | |
544 | iowait = ts->iowait_sleeptime; | |
545 | } else { | |
546 | if (ts->idle_active && nr_iowait_cpu(cpu) > 0) { | |
547 | ktime_t delta = ktime_sub(now, ts->idle_entrytime); | |
0224cf4c | 548 | |
09a1d34f MH |
549 | iowait = ktime_add(ts->iowait_sleeptime, delta); |
550 | } else { | |
551 | iowait = ts->iowait_sleeptime; | |
552 | } | |
553 | } | |
0224cf4c | 554 | |
09a1d34f | 555 | return ktime_to_us(iowait); |
0224cf4c AV |
556 | } |
557 | EXPORT_SYMBOL_GPL(get_cpu_iowait_time_us); | |
558 | ||
0ff53d09 TG |
559 | static void tick_nohz_restart(struct tick_sched *ts, ktime_t now) |
560 | { | |
561 | hrtimer_cancel(&ts->sched_timer); | |
562 | hrtimer_set_expires(&ts->sched_timer, ts->last_tick); | |
563 | ||
564 | /* Forward the time to expire in the future */ | |
565 | hrtimer_forward(&ts->sched_timer, now, tick_period); | |
566 | ||
567 | if (ts->nohz_mode == NOHZ_MODE_HIGHRES) | |
568 | hrtimer_start_expires(&ts->sched_timer, HRTIMER_MODE_ABS_PINNED); | |
569 | else | |
570 | tick_program_event(hrtimer_get_expires(&ts->sched_timer), 1); | |
571 | } | |
572 | ||
84bf1bcc FW |
573 | static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts, |
574 | ktime_t now, int cpu) | |
79bf2bb3 | 575 | { |
22127e93 | 576 | struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev); |
c1ad348b TG |
577 | u64 basemono, next_tick, next_tmr, next_rcu, delta, expires; |
578 | unsigned long seq, basejiff; | |
579 | ktime_t tick; | |
855a0fc3 | 580 | |
79bf2bb3 TG |
581 | /* Read jiffies and the time when jiffies were updated last */ |
582 | do { | |
d6ad4187 | 583 | seq = read_seqbegin(&jiffies_lock); |
c1ad348b TG |
584 | basemono = last_jiffies_update.tv64; |
585 | basejiff = jiffies; | |
d6ad4187 | 586 | } while (read_seqretry(&jiffies_lock, seq)); |
c1ad348b | 587 | ts->last_jiffies = basejiff; |
79bf2bb3 | 588 | |
c1ad348b | 589 | if (rcu_needs_cpu(basemono, &next_rcu) || |
fe0f4976 | 590 | arch_needs_cpu() || irq_work_needs_cpu()) { |
c1ad348b | 591 | next_tick = basemono + TICK_NSEC; |
3c5d92a0 | 592 | } else { |
c1ad348b TG |
593 | /* |
594 | * Get the next pending timer. If high resolution | |
595 | * timers are enabled this only takes the timer wheel | |
596 | * timers into account. If high resolution timers are | |
597 | * disabled this also looks at the next expiring | |
598 | * hrtimer. | |
599 | */ | |
600 | next_tmr = get_next_timer_interrupt(basejiff, basemono); | |
601 | ts->next_timer = next_tmr; | |
602 | /* Take the next rcu event into account */ | |
603 | next_tick = next_rcu < next_tmr ? next_rcu : next_tmr; | |
3c5d92a0 | 604 | } |
47aa8b6c | 605 | |
c1ad348b TG |
606 | /* |
607 | * If the tick is due in the next period, keep it ticking or | |
82bbe34b | 608 | * force prod the timer. |
c1ad348b TG |
609 | */ |
610 | delta = next_tick - basemono; | |
611 | if (delta <= (u64)TICK_NSEC) { | |
612 | tick.tv64 = 0; | |
82bbe34b PZ |
613 | /* |
614 | * We've not stopped the tick yet, and there's a timer in the | |
615 | * next period, so no point in stopping it either, bail. | |
616 | */ | |
157d29e1 TG |
617 | if (!ts->tick_stopped) |
618 | goto out; | |
82bbe34b PZ |
619 | |
620 | /* | |
621 | * If, OTOH, we did stop it, but there's a pending (expired) | |
622 | * timer reprogram the timer hardware to fire now. | |
623 | * | |
624 | * We will not restart the tick proper, just prod the timer | |
625 | * hardware into firing an interrupt to process the pending | |
626 | * timers. Just like tick_irq_exit() will not restart the tick | |
627 | * for 'normal' interrupts. | |
628 | * | |
629 | * Only once we exit the idle loop will we re-enable the tick, | |
630 | * see tick_nohz_idle_exit(). | |
631 | */ | |
c1ad348b | 632 | if (delta == 0) { |
157d29e1 TG |
633 | tick_nohz_restart(ts, now); |
634 | goto out; | |
635 | } | |
636 | } | |
637 | ||
79bf2bb3 | 638 | /* |
157d29e1 TG |
639 | * If this cpu is the one which updates jiffies, then give up |
640 | * the assignment and let it be taken by the cpu which runs | |
641 | * the tick timer next, which might be this cpu as well. If we | |
642 | * don't drop this here the jiffies might be stale and | |
643 | * do_timer() never invoked. Keep track of the fact that it | |
644 | * was the one which had the do_timer() duty last. If this cpu | |
645 | * is the one which had the do_timer() duty last, we limit the | |
c1ad348b TG |
646 | * sleep time to the timekeeping max_deferement value. |
647 | * Otherwise we can sleep as long as we want. | |
79bf2bb3 | 648 | */ |
c1ad348b | 649 | delta = timekeeping_max_deferment(); |
157d29e1 TG |
650 | if (cpu == tick_do_timer_cpu) { |
651 | tick_do_timer_cpu = TICK_DO_TIMER_NONE; | |
652 | ts->do_timer_last = 1; | |
653 | } else if (tick_do_timer_cpu != TICK_DO_TIMER_NONE) { | |
c1ad348b | 654 | delta = KTIME_MAX; |
157d29e1 TG |
655 | ts->do_timer_last = 0; |
656 | } else if (!ts->do_timer_last) { | |
c1ad348b | 657 | delta = KTIME_MAX; |
157d29e1 | 658 | } |
27185016 | 659 | |
265f22a9 | 660 | #ifdef CONFIG_NO_HZ_FULL |
c1ad348b | 661 | /* Limit the tick delta to the maximum scheduler deferment */ |
157d29e1 | 662 | if (!ts->inidle) |
c1ad348b | 663 | delta = min(delta, scheduler_tick_max_deferment()); |
265f22a9 FW |
664 | #endif |
665 | ||
c1ad348b TG |
666 | /* Calculate the next expiry time */ |
667 | if (delta < (KTIME_MAX - basemono)) | |
668 | expires = basemono + delta; | |
157d29e1 | 669 | else |
c1ad348b TG |
670 | expires = KTIME_MAX; |
671 | ||
672 | expires = min_t(u64, expires, next_tick); | |
673 | tick.tv64 = expires; | |
00147449 | 674 | |
157d29e1 | 675 | /* Skip reprogram of event if its not changed */ |
c1ad348b | 676 | if (ts->tick_stopped && (expires == dev->next_event.tv64)) |
157d29e1 | 677 | goto out; |
84bf1bcc | 678 | |
157d29e1 TG |
679 | /* |
680 | * nohz_stop_sched_tick can be called several times before | |
681 | * the nohz_restart_sched_tick is called. This happens when | |
682 | * interrupts arrive which do not cause a reschedule. In the | |
683 | * first call we save the current tick time, so we can restart | |
684 | * the scheduler tick in nohz_restart_sched_tick. | |
685 | */ | |
686 | if (!ts->tick_stopped) { | |
687 | nohz_balance_enter_idle(cpu); | |
688 | calc_load_enter_idle(); | |
d3ed7824 | 689 | |
157d29e1 TG |
690 | ts->last_tick = hrtimer_get_expires(&ts->sched_timer); |
691 | ts->tick_stopped = 1; | |
692 | trace_tick_stop(1, " "); | |
693 | } | |
eaad084b | 694 | |
157d29e1 | 695 | /* |
c1ad348b TG |
696 | * If the expiration time == KTIME_MAX, then we simply stop |
697 | * the tick timer. | |
157d29e1 | 698 | */ |
c1ad348b | 699 | if (unlikely(expires == KTIME_MAX)) { |
157d29e1 TG |
700 | if (ts->nohz_mode == NOHZ_MODE_HIGHRES) |
701 | hrtimer_cancel(&ts->sched_timer); | |
702 | goto out; | |
79bf2bb3 | 703 | } |
0ff53d09 | 704 | |
157d29e1 | 705 | if (ts->nohz_mode == NOHZ_MODE_HIGHRES) |
c1ad348b | 706 | hrtimer_start(&ts->sched_timer, tick, HRTIMER_MODE_ABS_PINNED); |
157d29e1 | 707 | else |
c1ad348b | 708 | tick_program_event(tick, 1); |
79bf2bb3 | 709 | out: |
c1ad348b | 710 | /* Update the estimated sleep length */ |
4f86d3a8 | 711 | ts->sleep_length = ktime_sub(dev->next_event, now); |
c1ad348b | 712 | return tick; |
280f0677 FW |
713 | } |
714 | ||
525705d1 | 715 | static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now, int active) |
59d2c7ca FW |
716 | { |
717 | /* Update jiffies first */ | |
718 | tick_do_update_jiffies64(now); | |
525705d1 | 719 | update_cpu_load_nohz(active); |
59d2c7ca FW |
720 | |
721 | calc_load_exit_idle(); | |
03e0d461 | 722 | touch_softlockup_watchdog_sched(); |
59d2c7ca FW |
723 | /* |
724 | * Cancel the scheduled timer and restore the tick | |
725 | */ | |
726 | ts->tick_stopped = 0; | |
727 | ts->idle_exittime = now; | |
728 | ||
729 | tick_nohz_restart(ts, now); | |
730 | } | |
73738a95 FW |
731 | |
732 | static void tick_nohz_full_update_tick(struct tick_sched *ts) | |
5811d996 FW |
733 | { |
734 | #ifdef CONFIG_NO_HZ_FULL | |
e9a2eb40 | 735 | int cpu = smp_processor_id(); |
5811d996 | 736 | |
59449359 | 737 | if (!tick_nohz_full_cpu(cpu)) |
e9a2eb40 | 738 | return; |
5811d996 | 739 | |
e9a2eb40 AS |
740 | if (!ts->tick_stopped && ts->nohz_mode == NOHZ_MODE_INACTIVE) |
741 | return; | |
5811d996 | 742 | |
73738a95 FW |
743 | if (can_stop_full_tick()) |
744 | tick_nohz_stop_sched_tick(ts, ktime_get(), cpu); | |
745 | else if (ts->tick_stopped) | |
525705d1 | 746 | tick_nohz_restart_sched_tick(ts, ktime_get(), 1); |
5811d996 FW |
747 | #endif |
748 | } | |
749 | ||
5b39939a FW |
750 | static bool can_stop_idle_tick(int cpu, struct tick_sched *ts) |
751 | { | |
752 | /* | |
753 | * If this cpu is offline and it is the one which updates | |
754 | * jiffies, then give up the assignment and let it be taken by | |
755 | * the cpu which runs the tick timer next. If we don't drop | |
756 | * this here the jiffies might be stale and do_timer() never | |
757 | * invoked. | |
758 | */ | |
759 | if (unlikely(!cpu_online(cpu))) { | |
760 | if (cpu == tick_do_timer_cpu) | |
761 | tick_do_timer_cpu = TICK_DO_TIMER_NONE; | |
f7ea0fd6 | 762 | return false; |
5b39939a FW |
763 | } |
764 | ||
0e576acb TG |
765 | if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE)) { |
766 | ts->sleep_length = (ktime_t) { .tv64 = NSEC_PER_SEC/HZ }; | |
5b39939a | 767 | return false; |
0e576acb | 768 | } |
5b39939a FW |
769 | |
770 | if (need_resched()) | |
771 | return false; | |
772 | ||
773 | if (unlikely(local_softirq_pending() && cpu_online(cpu))) { | |
774 | static int ratelimit; | |
775 | ||
803b0eba PM |
776 | if (ratelimit < 10 && |
777 | (local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK)) { | |
cfea7d7e RV |
778 | pr_warn("NOHZ: local_softirq_pending %02x\n", |
779 | (unsigned int) local_softirq_pending()); | |
5b39939a FW |
780 | ratelimit++; |
781 | } | |
782 | return false; | |
783 | } | |
784 | ||
460775df | 785 | if (tick_nohz_full_enabled()) { |
a382bf93 FW |
786 | /* |
787 | * Keep the tick alive to guarantee timekeeping progression | |
788 | * if there are full dynticks CPUs around | |
789 | */ | |
790 | if (tick_do_timer_cpu == cpu) | |
791 | return false; | |
792 | /* | |
793 | * Boot safety: make sure the timekeeping duty has been | |
794 | * assigned before entering dyntick-idle mode, | |
795 | */ | |
796 | if (tick_do_timer_cpu == TICK_DO_TIMER_NONE) | |
797 | return false; | |
798 | } | |
799 | ||
5b39939a FW |
800 | return true; |
801 | } | |
802 | ||
19f5f736 FW |
803 | static void __tick_nohz_idle_enter(struct tick_sched *ts) |
804 | { | |
84bf1bcc | 805 | ktime_t now, expires; |
5b39939a | 806 | int cpu = smp_processor_id(); |
19f5f736 | 807 | |
e8fcaa5c | 808 | now = tick_nohz_start_idle(ts); |
2ac0d98f | 809 | |
5b39939a FW |
810 | if (can_stop_idle_tick(cpu, ts)) { |
811 | int was_stopped = ts->tick_stopped; | |
812 | ||
813 | ts->idle_calls++; | |
84bf1bcc FW |
814 | |
815 | expires = tick_nohz_stop_sched_tick(ts, now, cpu); | |
816 | if (expires.tv64 > 0LL) { | |
817 | ts->idle_sleeps++; | |
818 | ts->idle_expires = expires; | |
819 | } | |
5b39939a FW |
820 | |
821 | if (!was_stopped && ts->tick_stopped) | |
822 | ts->idle_jiffies = ts->last_jiffies; | |
823 | } | |
280f0677 FW |
824 | } |
825 | ||
826 | /** | |
827 | * tick_nohz_idle_enter - stop the idle tick from the idle task | |
828 | * | |
829 | * When the next event is more than a tick into the future, stop the idle tick | |
830 | * Called when we start the idle loop. | |
2bbb6817 | 831 | * |
1268fbc7 | 832 | * The arch is responsible of calling: |
2bbb6817 FW |
833 | * |
834 | * - rcu_idle_enter() after its last use of RCU before the CPU is put | |
835 | * to sleep. | |
836 | * - rcu_idle_exit() before the first use of RCU after the CPU is woken up. | |
280f0677 | 837 | */ |
1268fbc7 | 838 | void tick_nohz_idle_enter(void) |
280f0677 FW |
839 | { |
840 | struct tick_sched *ts; | |
841 | ||
1268fbc7 FW |
842 | WARN_ON_ONCE(irqs_disabled()); |
843 | ||
0db49b72 LT |
844 | /* |
845 | * Update the idle state in the scheduler domain hierarchy | |
846 | * when tick_nohz_stop_sched_tick() is called from the idle loop. | |
847 | * State will be updated to busy during the first busy tick after | |
848 | * exiting idle. | |
849 | */ | |
850 | set_cpu_sd_state_idle(); | |
851 | ||
1268fbc7 FW |
852 | local_irq_disable(); |
853 | ||
22127e93 | 854 | ts = this_cpu_ptr(&tick_cpu_sched); |
280f0677 | 855 | ts->inidle = 1; |
19f5f736 | 856 | __tick_nohz_idle_enter(ts); |
1268fbc7 FW |
857 | |
858 | local_irq_enable(); | |
280f0677 FW |
859 | } |
860 | ||
861 | /** | |
862 | * tick_nohz_irq_exit - update next tick event from interrupt exit | |
863 | * | |
864 | * When an interrupt fires while we are idle and it doesn't cause | |
865 | * a reschedule, it may still add, modify or delete a timer, enqueue | |
866 | * an RCU callback, etc... | |
867 | * So we need to re-calculate and reprogram the next tick event. | |
868 | */ | |
869 | void tick_nohz_irq_exit(void) | |
870 | { | |
22127e93 | 871 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
280f0677 | 872 | |
14851912 | 873 | if (ts->inidle) |
5811d996 | 874 | __tick_nohz_idle_enter(ts); |
14851912 | 875 | else |
73738a95 | 876 | tick_nohz_full_update_tick(ts); |
79bf2bb3 TG |
877 | } |
878 | ||
4f86d3a8 LB |
879 | /** |
880 | * tick_nohz_get_sleep_length - return the length of the current sleep | |
881 | * | |
882 | * Called from power state control code with interrupts disabled | |
883 | */ | |
884 | ktime_t tick_nohz_get_sleep_length(void) | |
885 | { | |
22127e93 | 886 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
4f86d3a8 LB |
887 | |
888 | return ts->sleep_length; | |
889 | } | |
890 | ||
2ac0d98f FW |
891 | static void tick_nohz_account_idle_ticks(struct tick_sched *ts) |
892 | { | |
3f4724ea | 893 | #ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE |
2ac0d98f | 894 | unsigned long ticks; |
3f4724ea | 895 | |
55dbdcfa | 896 | if (vtime_accounting_cpu_enabled()) |
3f4724ea | 897 | return; |
79bf2bb3 TG |
898 | /* |
899 | * We stopped the tick in idle. Update process times would miss the | |
900 | * time we slept as update_process_times does only a 1 tick | |
901 | * accounting. Enforce that this is accounted to idle ! | |
902 | */ | |
903 | ticks = jiffies - ts->idle_jiffies; | |
904 | /* | |
905 | * We might be one off. Do not randomly account a huge number of ticks! | |
906 | */ | |
79741dd3 MS |
907 | if (ticks && ticks < LONG_MAX) |
908 | account_idle_ticks(ticks); | |
909 | #endif | |
19f5f736 FW |
910 | } |
911 | ||
79bf2bb3 | 912 | /** |
280f0677 | 913 | * tick_nohz_idle_exit - restart the idle tick from the idle task |
79bf2bb3 TG |
914 | * |
915 | * Restart the idle tick when the CPU is woken up from idle | |
280f0677 FW |
916 | * This also exit the RCU extended quiescent state. The CPU |
917 | * can use RCU again after this function is called. | |
79bf2bb3 | 918 | */ |
280f0677 | 919 | void tick_nohz_idle_exit(void) |
79bf2bb3 | 920 | { |
4a32fea9 | 921 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
6378ddb5 | 922 | ktime_t now; |
79bf2bb3 | 923 | |
6378ddb5 | 924 | local_irq_disable(); |
2bbb6817 | 925 | |
15f827be FW |
926 | WARN_ON_ONCE(!ts->inidle); |
927 | ||
928 | ts->inidle = 0; | |
929 | ||
930 | if (ts->idle_active || ts->tick_stopped) | |
eed3b9cf MS |
931 | now = ktime_get(); |
932 | ||
933 | if (ts->idle_active) | |
e8fcaa5c | 934 | tick_nohz_stop_idle(ts, now); |
6378ddb5 | 935 | |
2ac0d98f | 936 | if (ts->tick_stopped) { |
525705d1 | 937 | tick_nohz_restart_sched_tick(ts, now, 0); |
2ac0d98f | 938 | tick_nohz_account_idle_ticks(ts); |
6378ddb5 | 939 | } |
79bf2bb3 | 940 | |
79bf2bb3 TG |
941 | local_irq_enable(); |
942 | } | |
943 | ||
79bf2bb3 TG |
944 | /* |
945 | * The nohz low res interrupt handler | |
946 | */ | |
947 | static void tick_nohz_handler(struct clock_event_device *dev) | |
948 | { | |
22127e93 | 949 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
79bf2bb3 TG |
950 | struct pt_regs *regs = get_irq_regs(); |
951 | ktime_t now = ktime_get(); | |
952 | ||
953 | dev->next_event.tv64 = KTIME_MAX; | |
954 | ||
5bb96226 | 955 | tick_sched_do_timer(now); |
9e8f559b | 956 | tick_sched_handle(ts, regs); |
79bf2bb3 | 957 | |
b5e995e6 VK |
958 | /* No need to reprogram if we are running tickless */ |
959 | if (unlikely(ts->tick_stopped)) | |
960 | return; | |
961 | ||
0ff53d09 TG |
962 | hrtimer_forward(&ts->sched_timer, now, tick_period); |
963 | tick_program_event(hrtimer_get_expires(&ts->sched_timer), 1); | |
79bf2bb3 TG |
964 | } |
965 | ||
bc7a34b8 TG |
966 | static inline void tick_nohz_activate(struct tick_sched *ts, int mode) |
967 | { | |
968 | if (!tick_nohz_enabled) | |
969 | return; | |
970 | ts->nohz_mode = mode; | |
971 | /* One update is enough */ | |
972 | if (!test_and_set_bit(0, &tick_nohz_active)) | |
683be13a | 973 | timers_update_migration(true); |
bc7a34b8 TG |
974 | } |
975 | ||
79bf2bb3 TG |
976 | /** |
977 | * tick_nohz_switch_to_nohz - switch to nohz mode | |
978 | */ | |
979 | static void tick_nohz_switch_to_nohz(void) | |
980 | { | |
22127e93 | 981 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
79bf2bb3 TG |
982 | ktime_t next; |
983 | ||
27630532 | 984 | if (!tick_nohz_enabled) |
79bf2bb3 TG |
985 | return; |
986 | ||
6b442bc8 | 987 | if (tick_switch_to_oneshot(tick_nohz_handler)) |
79bf2bb3 | 988 | return; |
6b442bc8 | 989 | |
79bf2bb3 TG |
990 | /* |
991 | * Recycle the hrtimer in ts, so we can share the | |
992 | * hrtimer_forward with the highres code. | |
993 | */ | |
994 | hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); | |
995 | /* Get the next period */ | |
996 | next = tick_init_jiffy_update(); | |
997 | ||
0ff53d09 | 998 | hrtimer_set_expires(&ts->sched_timer, next); |
1ca8ec53 WL |
999 | hrtimer_forward_now(&ts->sched_timer, tick_period); |
1000 | tick_program_event(hrtimer_get_expires(&ts->sched_timer), 1); | |
bc7a34b8 | 1001 | tick_nohz_activate(ts, NOHZ_MODE_LOWRES); |
79bf2bb3 TG |
1002 | } |
1003 | ||
fb02fbc1 TG |
1004 | /* |
1005 | * When NOHZ is enabled and the tick is stopped, we need to kick the | |
1006 | * tick timer from irq_enter() so that the jiffies update is kept | |
1007 | * alive during long running softirqs. That's ugly as hell, but | |
1008 | * correctness is key even if we need to fix the offending softirq in | |
1009 | * the first place. | |
1010 | * | |
1011 | * Note, this is different to tick_nohz_restart. We just kick the | |
1012 | * timer and do not touch the other magic bits which need to be done | |
1013 | * when idle is left. | |
1014 | */ | |
e8fcaa5c | 1015 | static void tick_nohz_kick_tick(struct tick_sched *ts, ktime_t now) |
fb02fbc1 | 1016 | { |
ae99286b TG |
1017 | #if 0 |
1018 | /* Switch back to 2.6.27 behaviour */ | |
eed3b9cf | 1019 | ktime_t delta; |
fb02fbc1 | 1020 | |
c4bd822e TG |
1021 | /* |
1022 | * Do not touch the tick device, when the next expiry is either | |
1023 | * already reached or less/equal than the tick period. | |
1024 | */ | |
268a3dcf | 1025 | delta = ktime_sub(hrtimer_get_expires(&ts->sched_timer), now); |
c4bd822e TG |
1026 | if (delta.tv64 <= tick_period.tv64) |
1027 | return; | |
1028 | ||
1029 | tick_nohz_restart(ts, now); | |
ae99286b | 1030 | #endif |
fb02fbc1 TG |
1031 | } |
1032 | ||
5acac1be | 1033 | static inline void tick_nohz_irq_enter(void) |
eed3b9cf | 1034 | { |
4a32fea9 | 1035 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
eed3b9cf MS |
1036 | ktime_t now; |
1037 | ||
1038 | if (!ts->idle_active && !ts->tick_stopped) | |
1039 | return; | |
1040 | now = ktime_get(); | |
1041 | if (ts->idle_active) | |
e8fcaa5c | 1042 | tick_nohz_stop_idle(ts, now); |
eed3b9cf MS |
1043 | if (ts->tick_stopped) { |
1044 | tick_nohz_update_jiffies(now); | |
e8fcaa5c | 1045 | tick_nohz_kick_tick(ts, now); |
eed3b9cf MS |
1046 | } |
1047 | } | |
1048 | ||
79bf2bb3 TG |
1049 | #else |
1050 | ||
1051 | static inline void tick_nohz_switch_to_nohz(void) { } | |
5acac1be | 1052 | static inline void tick_nohz_irq_enter(void) { } |
bc7a34b8 | 1053 | static inline void tick_nohz_activate(struct tick_sched *ts, int mode) { } |
79bf2bb3 | 1054 | |
3451d024 | 1055 | #endif /* CONFIG_NO_HZ_COMMON */ |
79bf2bb3 | 1056 | |
719254fa TG |
1057 | /* |
1058 | * Called from irq_enter to notify about the possible interruption of idle() | |
1059 | */ | |
5acac1be | 1060 | void tick_irq_enter(void) |
719254fa | 1061 | { |
e8fcaa5c | 1062 | tick_check_oneshot_broadcast_this_cpu(); |
5acac1be | 1063 | tick_nohz_irq_enter(); |
719254fa TG |
1064 | } |
1065 | ||
79bf2bb3 TG |
1066 | /* |
1067 | * High resolution timer specific code | |
1068 | */ | |
1069 | #ifdef CONFIG_HIGH_RES_TIMERS | |
1070 | /* | |
4c9dc641 | 1071 | * We rearm the timer until we get disabled by the idle code. |
351f181f | 1072 | * Called with interrupts disabled. |
79bf2bb3 TG |
1073 | */ |
1074 | static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer) | |
1075 | { | |
1076 | struct tick_sched *ts = | |
1077 | container_of(timer, struct tick_sched, sched_timer); | |
79bf2bb3 TG |
1078 | struct pt_regs *regs = get_irq_regs(); |
1079 | ktime_t now = ktime_get(); | |
d3ed7824 | 1080 | |
5bb96226 | 1081 | tick_sched_do_timer(now); |
79bf2bb3 TG |
1082 | |
1083 | /* | |
1084 | * Do not call, when we are not in irq context and have | |
1085 | * no valid regs pointer | |
1086 | */ | |
9e8f559b FW |
1087 | if (regs) |
1088 | tick_sched_handle(ts, regs); | |
79bf2bb3 | 1089 | |
2a16fc93 VK |
1090 | /* No need to reprogram if we are in idle or full dynticks mode */ |
1091 | if (unlikely(ts->tick_stopped)) | |
1092 | return HRTIMER_NORESTART; | |
1093 | ||
79bf2bb3 TG |
1094 | hrtimer_forward(timer, now, tick_period); |
1095 | ||
1096 | return HRTIMER_RESTART; | |
1097 | } | |
1098 | ||
5307c955 MG |
1099 | static int sched_skew_tick; |
1100 | ||
62cf20b3 TG |
1101 | static int __init skew_tick(char *str) |
1102 | { | |
1103 | get_option(&str, &sched_skew_tick); | |
1104 | ||
1105 | return 0; | |
1106 | } | |
1107 | early_param("skew_tick", skew_tick); | |
1108 | ||
79bf2bb3 TG |
1109 | /** |
1110 | * tick_setup_sched_timer - setup the tick emulation timer | |
1111 | */ | |
1112 | void tick_setup_sched_timer(void) | |
1113 | { | |
22127e93 | 1114 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
79bf2bb3 TG |
1115 | ktime_t now = ktime_get(); |
1116 | ||
1117 | /* | |
1118 | * Emulate tick processing via per-CPU hrtimers: | |
1119 | */ | |
1120 | hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); | |
1121 | ts->sched_timer.function = tick_sched_timer; | |
79bf2bb3 | 1122 | |
3704540b | 1123 | /* Get the next period (per cpu) */ |
cc584b21 | 1124 | hrtimer_set_expires(&ts->sched_timer, tick_init_jiffy_update()); |
79bf2bb3 | 1125 | |
9c3f9e28 | 1126 | /* Offset the tick to avert jiffies_lock contention. */ |
5307c955 MG |
1127 | if (sched_skew_tick) { |
1128 | u64 offset = ktime_to_ns(tick_period) >> 1; | |
1129 | do_div(offset, num_possible_cpus()); | |
1130 | offset *= smp_processor_id(); | |
1131 | hrtimer_add_expires_ns(&ts->sched_timer, offset); | |
1132 | } | |
1133 | ||
afc08b15 TG |
1134 | hrtimer_forward(&ts->sched_timer, now, tick_period); |
1135 | hrtimer_start_expires(&ts->sched_timer, HRTIMER_MODE_ABS_PINNED); | |
bc7a34b8 | 1136 | tick_nohz_activate(ts, NOHZ_MODE_HIGHRES); |
79bf2bb3 | 1137 | } |
3c4fbe5e | 1138 | #endif /* HIGH_RES_TIMERS */ |
79bf2bb3 | 1139 | |
3451d024 | 1140 | #if defined CONFIG_NO_HZ_COMMON || defined CONFIG_HIGH_RES_TIMERS |
79bf2bb3 TG |
1141 | void tick_cancel_sched_timer(int cpu) |
1142 | { | |
1143 | struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); | |
1144 | ||
3c4fbe5e | 1145 | # ifdef CONFIG_HIGH_RES_TIMERS |
79bf2bb3 TG |
1146 | if (ts->sched_timer.base) |
1147 | hrtimer_cancel(&ts->sched_timer); | |
3c4fbe5e | 1148 | # endif |
a7901766 | 1149 | |
4b0c0f29 | 1150 | memset(ts, 0, sizeof(*ts)); |
79bf2bb3 | 1151 | } |
3c4fbe5e | 1152 | #endif |
79bf2bb3 TG |
1153 | |
1154 | /** | |
1155 | * Async notification about clocksource changes | |
1156 | */ | |
1157 | void tick_clock_notify(void) | |
1158 | { | |
1159 | int cpu; | |
1160 | ||
1161 | for_each_possible_cpu(cpu) | |
1162 | set_bit(0, &per_cpu(tick_cpu_sched, cpu).check_clocks); | |
1163 | } | |
1164 | ||
1165 | /* | |
1166 | * Async notification about clock event changes | |
1167 | */ | |
1168 | void tick_oneshot_notify(void) | |
1169 | { | |
22127e93 | 1170 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
79bf2bb3 TG |
1171 | |
1172 | set_bit(0, &ts->check_clocks); | |
1173 | } | |
1174 | ||
1175 | /** | |
1176 | * Check, if a change happened, which makes oneshot possible. | |
1177 | * | |
1178 | * Called cyclic from the hrtimer softirq (driven by the timer | |
1179 | * softirq) allow_nohz signals, that we can switch into low-res nohz | |
1180 | * mode, because high resolution timers are disabled (either compile | |
6b442bc8 | 1181 | * or runtime). Called with interrupts disabled. |
79bf2bb3 TG |
1182 | */ |
1183 | int tick_check_oneshot_change(int allow_nohz) | |
1184 | { | |
22127e93 | 1185 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
79bf2bb3 TG |
1186 | |
1187 | if (!test_and_clear_bit(0, &ts->check_clocks)) | |
1188 | return 0; | |
1189 | ||
1190 | if (ts->nohz_mode != NOHZ_MODE_INACTIVE) | |
1191 | return 0; | |
1192 | ||
cf4fc6cb | 1193 | if (!timekeeping_valid_for_hres() || !tick_is_oneshot_available()) |
79bf2bb3 TG |
1194 | return 0; |
1195 | ||
1196 | if (!allow_nohz) | |
1197 | return 1; | |
1198 | ||
1199 | tick_nohz_switch_to_nohz(); | |
1200 | return 0; | |
1201 | } |