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 TG |
38 | |
39 | /* | |
d6ad4187 | 40 | * The time, when the last jiffy update happened. Protected by jiffies_lock. |
79bf2bb3 TG |
41 | */ |
42 | static ktime_t last_jiffies_update; | |
43 | ||
289f480a IM |
44 | struct tick_sched *tick_get_tick_sched(int cpu) |
45 | { | |
46 | return &per_cpu(tick_cpu_sched, cpu); | |
47 | } | |
48 | ||
79bf2bb3 TG |
49 | /* |
50 | * Must be called with interrupts disabled ! | |
51 | */ | |
52 | static void tick_do_update_jiffies64(ktime_t now) | |
53 | { | |
54 | unsigned long ticks = 0; | |
55 | ktime_t delta; | |
56 | ||
7a14ce1d | 57 | /* |
d6ad4187 | 58 | * Do a quick check without holding jiffies_lock: |
7a14ce1d IM |
59 | */ |
60 | delta = ktime_sub(now, last_jiffies_update); | |
61 | if (delta.tv64 < tick_period.tv64) | |
62 | return; | |
63 | ||
d6ad4187 JS |
64 | /* Reevalute with jiffies_lock held */ |
65 | write_seqlock(&jiffies_lock); | |
79bf2bb3 TG |
66 | |
67 | delta = ktime_sub(now, last_jiffies_update); | |
68 | if (delta.tv64 >= tick_period.tv64) { | |
69 | ||
70 | delta = ktime_sub(delta, tick_period); | |
71 | last_jiffies_update = ktime_add(last_jiffies_update, | |
72 | tick_period); | |
73 | ||
74 | /* Slow path for long timeouts */ | |
75 | if (unlikely(delta.tv64 >= tick_period.tv64)) { | |
76 | s64 incr = ktime_to_ns(tick_period); | |
77 | ||
78 | ticks = ktime_divns(delta, incr); | |
79 | ||
80 | last_jiffies_update = ktime_add_ns(last_jiffies_update, | |
81 | incr * ticks); | |
82 | } | |
83 | do_timer(++ticks); | |
49d670fb TG |
84 | |
85 | /* Keep the tick_next_period variable up to date */ | |
86 | tick_next_period = ktime_add(last_jiffies_update, tick_period); | |
03e6bdc5 VK |
87 | } else { |
88 | write_sequnlock(&jiffies_lock); | |
89 | return; | |
79bf2bb3 | 90 | } |
d6ad4187 | 91 | write_sequnlock(&jiffies_lock); |
47a1b796 | 92 | update_wall_time(); |
79bf2bb3 TG |
93 | } |
94 | ||
95 | /* | |
96 | * Initialize and return retrieve the jiffies update. | |
97 | */ | |
98 | static ktime_t tick_init_jiffy_update(void) | |
99 | { | |
100 | ktime_t period; | |
101 | ||
d6ad4187 | 102 | write_seqlock(&jiffies_lock); |
79bf2bb3 TG |
103 | /* Did we start the jiffies update yet ? */ |
104 | if (last_jiffies_update.tv64 == 0) | |
105 | last_jiffies_update = tick_next_period; | |
106 | period = last_jiffies_update; | |
d6ad4187 | 107 | write_sequnlock(&jiffies_lock); |
79bf2bb3 TG |
108 | return period; |
109 | } | |
110 | ||
5bb96226 FW |
111 | |
112 | static void tick_sched_do_timer(ktime_t now) | |
113 | { | |
114 | int cpu = smp_processor_id(); | |
115 | ||
3451d024 | 116 | #ifdef CONFIG_NO_HZ_COMMON |
5bb96226 FW |
117 | /* |
118 | * Check if the do_timer duty was dropped. We don't care about | |
119 | * concurrency: This happens only when the cpu in charge went | |
120 | * into a long sleep. If two cpus happen to assign themself to | |
121 | * this duty, then the jiffies update is still serialized by | |
9c3f9e28 | 122 | * jiffies_lock. |
5bb96226 | 123 | */ |
a382bf93 | 124 | if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE) |
c5bfece2 | 125 | && !tick_nohz_full_cpu(cpu)) |
5bb96226 FW |
126 | tick_do_timer_cpu = cpu; |
127 | #endif | |
128 | ||
129 | /* Check, if the jiffies need an update */ | |
130 | if (tick_do_timer_cpu == cpu) | |
131 | tick_do_update_jiffies64(now); | |
132 | } | |
133 | ||
9e8f559b FW |
134 | static void tick_sched_handle(struct tick_sched *ts, struct pt_regs *regs) |
135 | { | |
3451d024 | 136 | #ifdef CONFIG_NO_HZ_COMMON |
9e8f559b FW |
137 | /* |
138 | * When we are idle and the tick is stopped, we have to touch | |
139 | * the watchdog as we might not schedule for a really long | |
140 | * time. This happens on complete idle SMP systems while | |
141 | * waiting on the login prompt. We also increment the "start of | |
142 | * idle" jiffy stamp so the idle accounting adjustment we do | |
143 | * when we go busy again does not account too much ticks. | |
144 | */ | |
145 | if (ts->tick_stopped) { | |
03e0d461 | 146 | touch_softlockup_watchdog_sched(); |
9e8f559b FW |
147 | if (is_idle_task(current)) |
148 | ts->idle_jiffies++; | |
149 | } | |
94a57140 | 150 | #endif |
9e8f559b FW |
151 | update_process_times(user_mode(regs)); |
152 | profile_tick(CPU_PROFILING); | |
153 | } | |
154 | ||
c5bfece2 | 155 | #ifdef CONFIG_NO_HZ_FULL |
460775df | 156 | cpumask_var_t tick_nohz_full_mask; |
c0f489d2 | 157 | cpumask_var_t housekeeping_mask; |
73867dcd | 158 | bool tick_nohz_full_running; |
a831881b | 159 | |
9014c45d FW |
160 | static bool can_stop_full_tick(void) |
161 | { | |
162 | WARN_ON_ONCE(!irqs_disabled()); | |
163 | ||
cb41a290 FW |
164 | if (!sched_can_stop_tick()) { |
165 | trace_tick_stop(0, "more than 1 task in runqueue\n"); | |
9014c45d | 166 | return false; |
cb41a290 | 167 | } |
9014c45d | 168 | |
cb41a290 FW |
169 | if (!posix_cpu_timers_can_stop_tick(current)) { |
170 | trace_tick_stop(0, "posix timers running\n"); | |
9014c45d | 171 | return false; |
cb41a290 | 172 | } |
9014c45d | 173 | |
cb41a290 FW |
174 | if (!perf_event_can_stop_tick()) { |
175 | trace_tick_stop(0, "perf events running\n"); | |
9014c45d | 176 | return false; |
cb41a290 | 177 | } |
9014c45d FW |
178 | |
179 | /* sched_clock_tick() needs us? */ | |
180 | #ifdef CONFIG_HAVE_UNSTABLE_SCHED_CLOCK | |
181 | /* | |
182 | * TODO: kick full dynticks CPUs when | |
183 | * sched_clock_stable is set. | |
184 | */ | |
35af99e6 | 185 | if (!sched_clock_stable()) { |
cb41a290 | 186 | trace_tick_stop(0, "unstable sched clock\n"); |
e12d0271 SR |
187 | /* |
188 | * Don't allow the user to think they can get | |
189 | * full NO_HZ with this machine. | |
190 | */ | |
73867dcd | 191 | WARN_ONCE(tick_nohz_full_running, |
543487c7 | 192 | "NO_HZ FULL will not work with unstable sched clock"); |
9014c45d | 193 | return false; |
cb41a290 | 194 | } |
9014c45d FW |
195 | #endif |
196 | ||
197 | return true; | |
198 | } | |
199 | ||
76c24fb0 FW |
200 | static void nohz_full_kick_work_func(struct irq_work *work) |
201 | { | |
73738a95 | 202 | /* Empty, the tick restart happens on tick_nohz_irq_exit() */ |
76c24fb0 FW |
203 | } |
204 | ||
205 | static DEFINE_PER_CPU(struct irq_work, nohz_full_kick_work) = { | |
206 | .func = nohz_full_kick_work_func, | |
207 | }; | |
208 | ||
40bea039 FW |
209 | /* |
210 | * Kick this CPU if it's full dynticks in order to force it to | |
211 | * re-evaluate its dependency on the tick and restart it if necessary. | |
212 | * This kick, unlike tick_nohz_full_kick_cpu() and tick_nohz_full_kick_all(), | |
213 | * is NMI safe. | |
214 | */ | |
215 | void tick_nohz_full_kick(void) | |
216 | { | |
217 | if (!tick_nohz_full_cpu(smp_processor_id())) | |
218 | return; | |
219 | ||
56e4dea8 | 220 | irq_work_queue(this_cpu_ptr(&nohz_full_kick_work)); |
40bea039 FW |
221 | } |
222 | ||
76c24fb0 | 223 | /* |
3d36aebc | 224 | * Kick the CPU if it's full dynticks in order to force it to |
76c24fb0 FW |
225 | * re-evaluate its dependency on the tick and restart it if necessary. |
226 | */ | |
3d36aebc | 227 | void tick_nohz_full_kick_cpu(int cpu) |
76c24fb0 | 228 | { |
3d36aebc FW |
229 | if (!tick_nohz_full_cpu(cpu)) |
230 | return; | |
231 | ||
232 | irq_work_queue_on(&per_cpu(nohz_full_kick_work, cpu), cpu); | |
76c24fb0 FW |
233 | } |
234 | ||
235 | static void nohz_full_kick_ipi(void *info) | |
236 | { | |
73738a95 | 237 | /* Empty, the tick restart happens on tick_nohz_irq_exit() */ |
76c24fb0 FW |
238 | } |
239 | ||
240 | /* | |
241 | * Kick all full dynticks CPUs in order to force these to re-evaluate | |
242 | * their dependency on the tick and restart it if necessary. | |
243 | */ | |
244 | void tick_nohz_full_kick_all(void) | |
245 | { | |
73867dcd | 246 | if (!tick_nohz_full_running) |
76c24fb0 FW |
247 | return; |
248 | ||
249 | preempt_disable(); | |
73867dcd | 250 | smp_call_function_many(tick_nohz_full_mask, |
76c24fb0 | 251 | nohz_full_kick_ipi, NULL, false); |
c2e7fcf5 | 252 | tick_nohz_full_kick(); |
76c24fb0 FW |
253 | preempt_enable(); |
254 | } | |
255 | ||
99e5ada9 FW |
256 | /* |
257 | * Re-evaluate the need for the tick as we switch the current task. | |
258 | * It might need the tick due to per task/process properties: | |
259 | * perf events, posix cpu timers, ... | |
260 | */ | |
de734f89 | 261 | void __tick_nohz_task_switch(void) |
99e5ada9 FW |
262 | { |
263 | unsigned long flags; | |
264 | ||
99e5ada9 FW |
265 | local_irq_save(flags); |
266 | ||
6296ace4 LZ |
267 | if (!tick_nohz_full_cpu(smp_processor_id())) |
268 | goto out; | |
269 | ||
99e5ada9 FW |
270 | if (tick_nohz_tick_stopped() && !can_stop_full_tick()) |
271 | tick_nohz_full_kick(); | |
272 | ||
6296ace4 | 273 | out: |
99e5ada9 FW |
274 | local_irq_restore(flags); |
275 | } | |
276 | ||
a831881b | 277 | /* Parse the boot-time nohz CPU list from the kernel parameters. */ |
c5bfece2 | 278 | static int __init tick_nohz_full_setup(char *str) |
a831881b | 279 | { |
73867dcd FW |
280 | alloc_bootmem_cpumask_var(&tick_nohz_full_mask); |
281 | if (cpulist_parse(str, tick_nohz_full_mask) < 0) { | |
c5bfece2 | 282 | pr_warning("NOHZ: Incorrect nohz_full cpumask\n"); |
4327b15f | 283 | free_bootmem_cpumask_var(tick_nohz_full_mask); |
0453b435 FW |
284 | return 1; |
285 | } | |
73867dcd | 286 | tick_nohz_full_running = true; |
0453b435 | 287 | |
a831881b FW |
288 | return 1; |
289 | } | |
c5bfece2 | 290 | __setup("nohz_full=", tick_nohz_full_setup); |
a831881b | 291 | |
0db0628d | 292 | static int tick_nohz_cpu_down_callback(struct notifier_block *nfb, |
7c8bb6cb FW |
293 | unsigned long action, |
294 | void *hcpu) | |
a382bf93 FW |
295 | { |
296 | unsigned int cpu = (unsigned long)hcpu; | |
297 | ||
298 | switch (action & ~CPU_TASKS_FROZEN) { | |
299 | case CPU_DOWN_PREPARE: | |
300 | /* | |
7c8bb6cb FW |
301 | * The boot CPU handles housekeeping duty (unbound timers, |
302 | * workqueues, timekeeping, ...) on behalf of full dynticks | |
303 | * CPUs. It must remain online when nohz full is enabled. | |
a382bf93 | 304 | */ |
73867dcd | 305 | if (tick_nohz_full_running && tick_do_timer_cpu == cpu) |
1a7f829f | 306 | return NOTIFY_BAD; |
a382bf93 FW |
307 | break; |
308 | } | |
309 | return NOTIFY_OK; | |
310 | } | |
311 | ||
f98823ac FW |
312 | static int tick_nohz_init_all(void) |
313 | { | |
314 | int err = -1; | |
315 | ||
316 | #ifdef CONFIG_NO_HZ_FULL_ALL | |
73867dcd | 317 | if (!alloc_cpumask_var(&tick_nohz_full_mask, GFP_KERNEL)) { |
4327b15f | 318 | WARN(1, "NO_HZ: Can't allocate full dynticks cpumask\n"); |
c0f489d2 PM |
319 | return err; |
320 | } | |
f98823ac | 321 | err = 0; |
73867dcd | 322 | cpumask_setall(tick_nohz_full_mask); |
73867dcd | 323 | tick_nohz_full_running = true; |
f98823ac FW |
324 | #endif |
325 | return err; | |
326 | } | |
327 | ||
d1e43fa5 | 328 | void __init tick_nohz_init(void) |
a831881b | 329 | { |
d1e43fa5 FW |
330 | int cpu; |
331 | ||
73867dcd | 332 | if (!tick_nohz_full_running) { |
f98823ac FW |
333 | if (tick_nohz_init_all() < 0) |
334 | return; | |
335 | } | |
d1e43fa5 | 336 | |
4327b15f FW |
337 | if (!alloc_cpumask_var(&housekeeping_mask, GFP_KERNEL)) { |
338 | WARN(1, "NO_HZ: Can't allocate not-full dynticks cpumask\n"); | |
339 | cpumask_clear(tick_nohz_full_mask); | |
340 | tick_nohz_full_running = false; | |
341 | return; | |
342 | } | |
343 | ||
9b01f5bf FW |
344 | /* |
345 | * Full dynticks uses irq work to drive the tick rescheduling on safe | |
346 | * locking contexts. But then we need irq work to raise its own | |
347 | * interrupts to avoid circular dependency on the tick | |
348 | */ | |
349 | if (!arch_irq_work_has_interrupt()) { | |
350 | pr_warning("NO_HZ: Can't run full dynticks because arch doesn't " | |
351 | "support irq work self-IPIs\n"); | |
352 | cpumask_clear(tick_nohz_full_mask); | |
353 | cpumask_copy(housekeeping_mask, cpu_possible_mask); | |
354 | tick_nohz_full_running = false; | |
355 | return; | |
356 | } | |
357 | ||
4327b15f FW |
358 | cpu = smp_processor_id(); |
359 | ||
360 | if (cpumask_test_cpu(cpu, tick_nohz_full_mask)) { | |
361 | pr_warning("NO_HZ: Clearing %d from nohz_full range for timekeeping\n", cpu); | |
362 | cpumask_clear_cpu(cpu, tick_nohz_full_mask); | |
363 | } | |
364 | ||
365 | cpumask_andnot(housekeeping_mask, | |
366 | cpu_possible_mask, tick_nohz_full_mask); | |
367 | ||
73867dcd | 368 | for_each_cpu(cpu, tick_nohz_full_mask) |
2e709338 FW |
369 | context_tracking_cpu_set(cpu); |
370 | ||
d1e43fa5 | 371 | cpu_notifier(tick_nohz_cpu_down_callback, 0); |
ffda22c1 TH |
372 | pr_info("NO_HZ: Full dynticks CPUs: %*pbl.\n", |
373 | cpumask_pr_args(tick_nohz_full_mask)); | |
7c8bb6cb FW |
374 | |
375 | /* | |
376 | * We need at least one CPU to handle housekeeping work such | |
377 | * as timekeeping, unbound timers, workqueues, ... | |
378 | */ | |
379 | WARN_ON_ONCE(cpumask_empty(housekeeping_mask)); | |
a831881b | 380 | } |
a831881b FW |
381 | #endif |
382 | ||
79bf2bb3 TG |
383 | /* |
384 | * NOHZ - aka dynamic tick functionality | |
385 | */ | |
3451d024 | 386 | #ifdef CONFIG_NO_HZ_COMMON |
79bf2bb3 TG |
387 | /* |
388 | * NO HZ enabled ? | |
389 | */ | |
46373a15 | 390 | int tick_nohz_enabled __read_mostly = 1; |
bc7a34b8 | 391 | unsigned long tick_nohz_active __read_mostly; |
79bf2bb3 TG |
392 | /* |
393 | * Enable / Disable tickless mode | |
394 | */ | |
395 | static int __init setup_tick_nohz(char *str) | |
396 | { | |
397 | if (!strcmp(str, "off")) | |
398 | tick_nohz_enabled = 0; | |
399 | else if (!strcmp(str, "on")) | |
400 | tick_nohz_enabled = 1; | |
401 | else | |
402 | return 0; | |
403 | return 1; | |
404 | } | |
405 | ||
406 | __setup("nohz=", setup_tick_nohz); | |
407 | ||
c1797baf TG |
408 | int tick_nohz_tick_stopped(void) |
409 | { | |
410 | return __this_cpu_read(tick_cpu_sched.tick_stopped); | |
411 | } | |
412 | ||
79bf2bb3 TG |
413 | /** |
414 | * tick_nohz_update_jiffies - update jiffies when idle was interrupted | |
415 | * | |
416 | * Called from interrupt entry when the CPU was idle | |
417 | * | |
418 | * In case the sched_tick was stopped on this CPU, we have to check if jiffies | |
419 | * must be updated. Otherwise an interrupt handler could use a stale jiffy | |
420 | * value. We do this unconditionally on any cpu, as we don't know whether the | |
421 | * cpu, which has the update task assigned is in a long sleep. | |
422 | */ | |
eed3b9cf | 423 | static void tick_nohz_update_jiffies(ktime_t now) |
79bf2bb3 | 424 | { |
79bf2bb3 | 425 | unsigned long flags; |
79bf2bb3 | 426 | |
e8fcaa5c | 427 | __this_cpu_write(tick_cpu_sched.idle_waketime, now); |
79bf2bb3 TG |
428 | |
429 | local_irq_save(flags); | |
430 | tick_do_update_jiffies64(now); | |
431 | local_irq_restore(flags); | |
02ff3755 | 432 | |
03e0d461 | 433 | touch_softlockup_watchdog_sched(); |
79bf2bb3 TG |
434 | } |
435 | ||
595aac48 AV |
436 | /* |
437 | * Updates the per cpu time idle statistics counters | |
438 | */ | |
8d63bf94 | 439 | static void |
8c215bd3 | 440 | update_ts_time_stats(int cpu, struct tick_sched *ts, ktime_t now, u64 *last_update_time) |
6378ddb5 | 441 | { |
eed3b9cf | 442 | ktime_t delta; |
6378ddb5 | 443 | |
595aac48 AV |
444 | if (ts->idle_active) { |
445 | delta = ktime_sub(now, ts->idle_entrytime); | |
8c215bd3 | 446 | if (nr_iowait_cpu(cpu) > 0) |
0224cf4c | 447 | ts->iowait_sleeptime = ktime_add(ts->iowait_sleeptime, delta); |
6beea0cd MH |
448 | else |
449 | ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta); | |
8c7b09f4 | 450 | ts->idle_entrytime = now; |
595aac48 | 451 | } |
8d63bf94 | 452 | |
e0e37c20 | 453 | if (last_update_time) |
8d63bf94 AV |
454 | *last_update_time = ktime_to_us(now); |
455 | ||
595aac48 AV |
456 | } |
457 | ||
e8fcaa5c | 458 | static void tick_nohz_stop_idle(struct tick_sched *ts, ktime_t now) |
595aac48 | 459 | { |
e8fcaa5c | 460 | update_ts_time_stats(smp_processor_id(), ts, now, NULL); |
eed3b9cf | 461 | ts->idle_active = 0; |
56c7426b | 462 | |
eed3b9cf | 463 | sched_clock_idle_wakeup_event(0); |
6378ddb5 VP |
464 | } |
465 | ||
e8fcaa5c | 466 | static ktime_t tick_nohz_start_idle(struct tick_sched *ts) |
6378ddb5 | 467 | { |
430ee881 | 468 | ktime_t now = ktime_get(); |
595aac48 | 469 | |
6378ddb5 VP |
470 | ts->idle_entrytime = now; |
471 | ts->idle_active = 1; | |
56c7426b | 472 | sched_clock_idle_sleep_event(); |
6378ddb5 VP |
473 | return now; |
474 | } | |
475 | ||
b1f724c3 AV |
476 | /** |
477 | * get_cpu_idle_time_us - get the total idle time of a cpu | |
478 | * @cpu: CPU number to query | |
09a1d34f MH |
479 | * @last_update_time: variable to store update time in. Do not update |
480 | * counters if NULL. | |
b1f724c3 AV |
481 | * |
482 | * Return the cummulative idle time (since boot) for a given | |
6beea0cd | 483 | * CPU, in microseconds. |
b1f724c3 AV |
484 | * |
485 | * This time is measured via accounting rather than sampling, | |
486 | * and is as accurate as ktime_get() is. | |
487 | * | |
488 | * This function returns -1 if NOHZ is not enabled. | |
489 | */ | |
6378ddb5 VP |
490 | u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time) |
491 | { | |
492 | struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); | |
09a1d34f | 493 | ktime_t now, idle; |
6378ddb5 | 494 | |
d689fe22 | 495 | if (!tick_nohz_active) |
8083e4ad | 496 | return -1; |
497 | ||
09a1d34f MH |
498 | now = ktime_get(); |
499 | if (last_update_time) { | |
500 | update_ts_time_stats(cpu, ts, now, last_update_time); | |
501 | idle = ts->idle_sleeptime; | |
502 | } else { | |
503 | if (ts->idle_active && !nr_iowait_cpu(cpu)) { | |
504 | ktime_t delta = ktime_sub(now, ts->idle_entrytime); | |
505 | ||
506 | idle = ktime_add(ts->idle_sleeptime, delta); | |
507 | } else { | |
508 | idle = ts->idle_sleeptime; | |
509 | } | |
510 | } | |
511 | ||
512 | return ktime_to_us(idle); | |
8083e4ad | 513 | |
6378ddb5 | 514 | } |
8083e4ad | 515 | EXPORT_SYMBOL_GPL(get_cpu_idle_time_us); |
6378ddb5 | 516 | |
6beea0cd | 517 | /** |
0224cf4c AV |
518 | * get_cpu_iowait_time_us - get the total iowait time of a cpu |
519 | * @cpu: CPU number to query | |
09a1d34f MH |
520 | * @last_update_time: variable to store update time in. Do not update |
521 | * counters if NULL. | |
0224cf4c AV |
522 | * |
523 | * Return the cummulative iowait time (since boot) for a given | |
524 | * CPU, in microseconds. | |
525 | * | |
526 | * This time is measured via accounting rather than sampling, | |
527 | * and is as accurate as ktime_get() is. | |
528 | * | |
529 | * This function returns -1 if NOHZ is not enabled. | |
530 | */ | |
531 | u64 get_cpu_iowait_time_us(int cpu, u64 *last_update_time) | |
532 | { | |
533 | struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); | |
09a1d34f | 534 | ktime_t now, iowait; |
0224cf4c | 535 | |
d689fe22 | 536 | if (!tick_nohz_active) |
0224cf4c AV |
537 | return -1; |
538 | ||
09a1d34f MH |
539 | now = ktime_get(); |
540 | if (last_update_time) { | |
541 | update_ts_time_stats(cpu, ts, now, last_update_time); | |
542 | iowait = ts->iowait_sleeptime; | |
543 | } else { | |
544 | if (ts->idle_active && nr_iowait_cpu(cpu) > 0) { | |
545 | ktime_t delta = ktime_sub(now, ts->idle_entrytime); | |
0224cf4c | 546 | |
09a1d34f MH |
547 | iowait = ktime_add(ts->iowait_sleeptime, delta); |
548 | } else { | |
549 | iowait = ts->iowait_sleeptime; | |
550 | } | |
551 | } | |
0224cf4c | 552 | |
09a1d34f | 553 | return ktime_to_us(iowait); |
0224cf4c AV |
554 | } |
555 | EXPORT_SYMBOL_GPL(get_cpu_iowait_time_us); | |
556 | ||
0ff53d09 TG |
557 | static void tick_nohz_restart(struct tick_sched *ts, ktime_t now) |
558 | { | |
559 | hrtimer_cancel(&ts->sched_timer); | |
560 | hrtimer_set_expires(&ts->sched_timer, ts->last_tick); | |
561 | ||
562 | /* Forward the time to expire in the future */ | |
563 | hrtimer_forward(&ts->sched_timer, now, tick_period); | |
564 | ||
565 | if (ts->nohz_mode == NOHZ_MODE_HIGHRES) | |
566 | hrtimer_start_expires(&ts->sched_timer, HRTIMER_MODE_ABS_PINNED); | |
567 | else | |
568 | tick_program_event(hrtimer_get_expires(&ts->sched_timer), 1); | |
569 | } | |
570 | ||
84bf1bcc FW |
571 | static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts, |
572 | ktime_t now, int cpu) | |
79bf2bb3 | 573 | { |
22127e93 | 574 | struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev); |
c1ad348b TG |
575 | u64 basemono, next_tick, next_tmr, next_rcu, delta, expires; |
576 | unsigned long seq, basejiff; | |
577 | ktime_t tick; | |
855a0fc3 | 578 | |
79bf2bb3 TG |
579 | /* Read jiffies and the time when jiffies were updated last */ |
580 | do { | |
d6ad4187 | 581 | seq = read_seqbegin(&jiffies_lock); |
c1ad348b TG |
582 | basemono = last_jiffies_update.tv64; |
583 | basejiff = jiffies; | |
d6ad4187 | 584 | } while (read_seqretry(&jiffies_lock, seq)); |
c1ad348b | 585 | ts->last_jiffies = basejiff; |
79bf2bb3 | 586 | |
c1ad348b | 587 | if (rcu_needs_cpu(basemono, &next_rcu) || |
fe0f4976 | 588 | arch_needs_cpu() || irq_work_needs_cpu()) { |
c1ad348b | 589 | next_tick = basemono + TICK_NSEC; |
3c5d92a0 | 590 | } else { |
c1ad348b TG |
591 | /* |
592 | * Get the next pending timer. If high resolution | |
593 | * timers are enabled this only takes the timer wheel | |
594 | * timers into account. If high resolution timers are | |
595 | * disabled this also looks at the next expiring | |
596 | * hrtimer. | |
597 | */ | |
598 | next_tmr = get_next_timer_interrupt(basejiff, basemono); | |
599 | ts->next_timer = next_tmr; | |
600 | /* Take the next rcu event into account */ | |
601 | next_tick = next_rcu < next_tmr ? next_rcu : next_tmr; | |
3c5d92a0 | 602 | } |
47aa8b6c | 603 | |
c1ad348b TG |
604 | /* |
605 | * If the tick is due in the next period, keep it ticking or | |
82bbe34b | 606 | * force prod the timer. |
c1ad348b TG |
607 | */ |
608 | delta = next_tick - basemono; | |
609 | if (delta <= (u64)TICK_NSEC) { | |
610 | tick.tv64 = 0; | |
82bbe34b PZ |
611 | /* |
612 | * We've not stopped the tick yet, and there's a timer in the | |
613 | * next period, so no point in stopping it either, bail. | |
614 | */ | |
157d29e1 TG |
615 | if (!ts->tick_stopped) |
616 | goto out; | |
82bbe34b PZ |
617 | |
618 | /* | |
619 | * If, OTOH, we did stop it, but there's a pending (expired) | |
620 | * timer reprogram the timer hardware to fire now. | |
621 | * | |
622 | * We will not restart the tick proper, just prod the timer | |
623 | * hardware into firing an interrupt to process the pending | |
624 | * timers. Just like tick_irq_exit() will not restart the tick | |
625 | * for 'normal' interrupts. | |
626 | * | |
627 | * Only once we exit the idle loop will we re-enable the tick, | |
628 | * see tick_nohz_idle_exit(). | |
629 | */ | |
c1ad348b | 630 | if (delta == 0) { |
157d29e1 TG |
631 | tick_nohz_restart(ts, now); |
632 | goto out; | |
633 | } | |
634 | } | |
635 | ||
79bf2bb3 | 636 | /* |
157d29e1 TG |
637 | * If this cpu is the one which updates jiffies, then give up |
638 | * the assignment and let it be taken by the cpu which runs | |
639 | * the tick timer next, which might be this cpu as well. If we | |
640 | * don't drop this here the jiffies might be stale and | |
641 | * do_timer() never invoked. Keep track of the fact that it | |
642 | * was the one which had the do_timer() duty last. If this cpu | |
643 | * is the one which had the do_timer() duty last, we limit the | |
c1ad348b TG |
644 | * sleep time to the timekeeping max_deferement value. |
645 | * Otherwise we can sleep as long as we want. | |
79bf2bb3 | 646 | */ |
c1ad348b | 647 | delta = timekeeping_max_deferment(); |
157d29e1 TG |
648 | if (cpu == tick_do_timer_cpu) { |
649 | tick_do_timer_cpu = TICK_DO_TIMER_NONE; | |
650 | ts->do_timer_last = 1; | |
651 | } else if (tick_do_timer_cpu != TICK_DO_TIMER_NONE) { | |
c1ad348b | 652 | delta = KTIME_MAX; |
157d29e1 TG |
653 | ts->do_timer_last = 0; |
654 | } else if (!ts->do_timer_last) { | |
c1ad348b | 655 | delta = KTIME_MAX; |
157d29e1 | 656 | } |
27185016 | 657 | |
265f22a9 | 658 | #ifdef CONFIG_NO_HZ_FULL |
c1ad348b | 659 | /* Limit the tick delta to the maximum scheduler deferment */ |
157d29e1 | 660 | if (!ts->inidle) |
c1ad348b | 661 | delta = min(delta, scheduler_tick_max_deferment()); |
265f22a9 FW |
662 | #endif |
663 | ||
c1ad348b TG |
664 | /* Calculate the next expiry time */ |
665 | if (delta < (KTIME_MAX - basemono)) | |
666 | expires = basemono + delta; | |
157d29e1 | 667 | else |
c1ad348b TG |
668 | expires = KTIME_MAX; |
669 | ||
670 | expires = min_t(u64, expires, next_tick); | |
671 | tick.tv64 = expires; | |
00147449 | 672 | |
157d29e1 | 673 | /* Skip reprogram of event if its not changed */ |
c1ad348b | 674 | if (ts->tick_stopped && (expires == dev->next_event.tv64)) |
157d29e1 | 675 | goto out; |
84bf1bcc | 676 | |
157d29e1 TG |
677 | /* |
678 | * nohz_stop_sched_tick can be called several times before | |
679 | * the nohz_restart_sched_tick is called. This happens when | |
680 | * interrupts arrive which do not cause a reschedule. In the | |
681 | * first call we save the current tick time, so we can restart | |
682 | * the scheduler tick in nohz_restart_sched_tick. | |
683 | */ | |
684 | if (!ts->tick_stopped) { | |
685 | nohz_balance_enter_idle(cpu); | |
686 | calc_load_enter_idle(); | |
d3ed7824 | 687 | |
157d29e1 TG |
688 | ts->last_tick = hrtimer_get_expires(&ts->sched_timer); |
689 | ts->tick_stopped = 1; | |
690 | trace_tick_stop(1, " "); | |
691 | } | |
eaad084b | 692 | |
157d29e1 | 693 | /* |
c1ad348b TG |
694 | * If the expiration time == KTIME_MAX, then we simply stop |
695 | * the tick timer. | |
157d29e1 | 696 | */ |
c1ad348b | 697 | if (unlikely(expires == KTIME_MAX)) { |
157d29e1 TG |
698 | if (ts->nohz_mode == NOHZ_MODE_HIGHRES) |
699 | hrtimer_cancel(&ts->sched_timer); | |
700 | goto out; | |
79bf2bb3 | 701 | } |
0ff53d09 | 702 | |
157d29e1 | 703 | if (ts->nohz_mode == NOHZ_MODE_HIGHRES) |
c1ad348b | 704 | hrtimer_start(&ts->sched_timer, tick, HRTIMER_MODE_ABS_PINNED); |
157d29e1 | 705 | else |
c1ad348b | 706 | tick_program_event(tick, 1); |
79bf2bb3 | 707 | out: |
c1ad348b | 708 | /* Update the estimated sleep length */ |
4f86d3a8 | 709 | ts->sleep_length = ktime_sub(dev->next_event, now); |
c1ad348b | 710 | return tick; |
280f0677 FW |
711 | } |
712 | ||
525705d1 | 713 | static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now, int active) |
59d2c7ca FW |
714 | { |
715 | /* Update jiffies first */ | |
716 | tick_do_update_jiffies64(now); | |
525705d1 | 717 | update_cpu_load_nohz(active); |
59d2c7ca FW |
718 | |
719 | calc_load_exit_idle(); | |
03e0d461 | 720 | touch_softlockup_watchdog_sched(); |
59d2c7ca FW |
721 | /* |
722 | * Cancel the scheduled timer and restore the tick | |
723 | */ | |
724 | ts->tick_stopped = 0; | |
725 | ts->idle_exittime = now; | |
726 | ||
727 | tick_nohz_restart(ts, now); | |
728 | } | |
73738a95 FW |
729 | |
730 | static void tick_nohz_full_update_tick(struct tick_sched *ts) | |
5811d996 FW |
731 | { |
732 | #ifdef CONFIG_NO_HZ_FULL | |
e9a2eb40 | 733 | int cpu = smp_processor_id(); |
5811d996 | 734 | |
59449359 | 735 | if (!tick_nohz_full_cpu(cpu)) |
e9a2eb40 | 736 | return; |
5811d996 | 737 | |
e9a2eb40 AS |
738 | if (!ts->tick_stopped && ts->nohz_mode == NOHZ_MODE_INACTIVE) |
739 | return; | |
5811d996 | 740 | |
73738a95 FW |
741 | if (can_stop_full_tick()) |
742 | tick_nohz_stop_sched_tick(ts, ktime_get(), cpu); | |
743 | else if (ts->tick_stopped) | |
525705d1 | 744 | tick_nohz_restart_sched_tick(ts, ktime_get(), 1); |
5811d996 FW |
745 | #endif |
746 | } | |
747 | ||
5b39939a FW |
748 | static bool can_stop_idle_tick(int cpu, struct tick_sched *ts) |
749 | { | |
750 | /* | |
751 | * If this cpu is offline and it is the one which updates | |
752 | * jiffies, then give up the assignment and let it be taken by | |
753 | * the cpu which runs the tick timer next. If we don't drop | |
754 | * this here the jiffies might be stale and do_timer() never | |
755 | * invoked. | |
756 | */ | |
757 | if (unlikely(!cpu_online(cpu))) { | |
758 | if (cpu == tick_do_timer_cpu) | |
759 | tick_do_timer_cpu = TICK_DO_TIMER_NONE; | |
f7ea0fd6 | 760 | return false; |
5b39939a FW |
761 | } |
762 | ||
0e576acb TG |
763 | if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE)) { |
764 | ts->sleep_length = (ktime_t) { .tv64 = NSEC_PER_SEC/HZ }; | |
5b39939a | 765 | return false; |
0e576acb | 766 | } |
5b39939a FW |
767 | |
768 | if (need_resched()) | |
769 | return false; | |
770 | ||
771 | if (unlikely(local_softirq_pending() && cpu_online(cpu))) { | |
772 | static int ratelimit; | |
773 | ||
803b0eba PM |
774 | if (ratelimit < 10 && |
775 | (local_softirq_pending() & SOFTIRQ_STOP_IDLE_MASK)) { | |
cfea7d7e RV |
776 | pr_warn("NOHZ: local_softirq_pending %02x\n", |
777 | (unsigned int) local_softirq_pending()); | |
5b39939a FW |
778 | ratelimit++; |
779 | } | |
780 | return false; | |
781 | } | |
782 | ||
460775df | 783 | if (tick_nohz_full_enabled()) { |
a382bf93 FW |
784 | /* |
785 | * Keep the tick alive to guarantee timekeeping progression | |
786 | * if there are full dynticks CPUs around | |
787 | */ | |
788 | if (tick_do_timer_cpu == cpu) | |
789 | return false; | |
790 | /* | |
791 | * Boot safety: make sure the timekeeping duty has been | |
792 | * assigned before entering dyntick-idle mode, | |
793 | */ | |
794 | if (tick_do_timer_cpu == TICK_DO_TIMER_NONE) | |
795 | return false; | |
796 | } | |
797 | ||
5b39939a FW |
798 | return true; |
799 | } | |
800 | ||
19f5f736 FW |
801 | static void __tick_nohz_idle_enter(struct tick_sched *ts) |
802 | { | |
84bf1bcc | 803 | ktime_t now, expires; |
5b39939a | 804 | int cpu = smp_processor_id(); |
19f5f736 | 805 | |
e8fcaa5c | 806 | now = tick_nohz_start_idle(ts); |
2ac0d98f | 807 | |
5b39939a FW |
808 | if (can_stop_idle_tick(cpu, ts)) { |
809 | int was_stopped = ts->tick_stopped; | |
810 | ||
811 | ts->idle_calls++; | |
84bf1bcc FW |
812 | |
813 | expires = tick_nohz_stop_sched_tick(ts, now, cpu); | |
814 | if (expires.tv64 > 0LL) { | |
815 | ts->idle_sleeps++; | |
816 | ts->idle_expires = expires; | |
817 | } | |
5b39939a FW |
818 | |
819 | if (!was_stopped && ts->tick_stopped) | |
820 | ts->idle_jiffies = ts->last_jiffies; | |
821 | } | |
280f0677 FW |
822 | } |
823 | ||
824 | /** | |
825 | * tick_nohz_idle_enter - stop the idle tick from the idle task | |
826 | * | |
827 | * When the next event is more than a tick into the future, stop the idle tick | |
828 | * Called when we start the idle loop. | |
2bbb6817 | 829 | * |
1268fbc7 | 830 | * The arch is responsible of calling: |
2bbb6817 FW |
831 | * |
832 | * - rcu_idle_enter() after its last use of RCU before the CPU is put | |
833 | * to sleep. | |
834 | * - rcu_idle_exit() before the first use of RCU after the CPU is woken up. | |
280f0677 | 835 | */ |
1268fbc7 | 836 | void tick_nohz_idle_enter(void) |
280f0677 FW |
837 | { |
838 | struct tick_sched *ts; | |
839 | ||
1268fbc7 FW |
840 | WARN_ON_ONCE(irqs_disabled()); |
841 | ||
0db49b72 LT |
842 | /* |
843 | * Update the idle state in the scheduler domain hierarchy | |
844 | * when tick_nohz_stop_sched_tick() is called from the idle loop. | |
845 | * State will be updated to busy during the first busy tick after | |
846 | * exiting idle. | |
847 | */ | |
848 | set_cpu_sd_state_idle(); | |
849 | ||
1268fbc7 FW |
850 | local_irq_disable(); |
851 | ||
22127e93 | 852 | ts = this_cpu_ptr(&tick_cpu_sched); |
280f0677 | 853 | ts->inidle = 1; |
19f5f736 | 854 | __tick_nohz_idle_enter(ts); |
1268fbc7 FW |
855 | |
856 | local_irq_enable(); | |
280f0677 FW |
857 | } |
858 | ||
859 | /** | |
860 | * tick_nohz_irq_exit - update next tick event from interrupt exit | |
861 | * | |
862 | * When an interrupt fires while we are idle and it doesn't cause | |
863 | * a reschedule, it may still add, modify or delete a timer, enqueue | |
864 | * an RCU callback, etc... | |
865 | * So we need to re-calculate and reprogram the next tick event. | |
866 | */ | |
867 | void tick_nohz_irq_exit(void) | |
868 | { | |
22127e93 | 869 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
280f0677 | 870 | |
14851912 | 871 | if (ts->inidle) |
5811d996 | 872 | __tick_nohz_idle_enter(ts); |
14851912 | 873 | else |
73738a95 | 874 | tick_nohz_full_update_tick(ts); |
79bf2bb3 TG |
875 | } |
876 | ||
4f86d3a8 LB |
877 | /** |
878 | * tick_nohz_get_sleep_length - return the length of the current sleep | |
879 | * | |
880 | * Called from power state control code with interrupts disabled | |
881 | */ | |
882 | ktime_t tick_nohz_get_sleep_length(void) | |
883 | { | |
22127e93 | 884 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
4f86d3a8 LB |
885 | |
886 | return ts->sleep_length; | |
887 | } | |
888 | ||
2ac0d98f FW |
889 | static void tick_nohz_account_idle_ticks(struct tick_sched *ts) |
890 | { | |
3f4724ea | 891 | #ifndef CONFIG_VIRT_CPU_ACCOUNTING_NATIVE |
2ac0d98f | 892 | unsigned long ticks; |
3f4724ea | 893 | |
55dbdcfa | 894 | if (vtime_accounting_cpu_enabled()) |
3f4724ea | 895 | return; |
79bf2bb3 TG |
896 | /* |
897 | * We stopped the tick in idle. Update process times would miss the | |
898 | * time we slept as update_process_times does only a 1 tick | |
899 | * accounting. Enforce that this is accounted to idle ! | |
900 | */ | |
901 | ticks = jiffies - ts->idle_jiffies; | |
902 | /* | |
903 | * We might be one off. Do not randomly account a huge number of ticks! | |
904 | */ | |
79741dd3 MS |
905 | if (ticks && ticks < LONG_MAX) |
906 | account_idle_ticks(ticks); | |
907 | #endif | |
19f5f736 FW |
908 | } |
909 | ||
79bf2bb3 | 910 | /** |
280f0677 | 911 | * tick_nohz_idle_exit - restart the idle tick from the idle task |
79bf2bb3 TG |
912 | * |
913 | * Restart the idle tick when the CPU is woken up from idle | |
280f0677 FW |
914 | * This also exit the RCU extended quiescent state. The CPU |
915 | * can use RCU again after this function is called. | |
79bf2bb3 | 916 | */ |
280f0677 | 917 | void tick_nohz_idle_exit(void) |
79bf2bb3 | 918 | { |
4a32fea9 | 919 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
6378ddb5 | 920 | ktime_t now; |
79bf2bb3 | 921 | |
6378ddb5 | 922 | local_irq_disable(); |
2bbb6817 | 923 | |
15f827be FW |
924 | WARN_ON_ONCE(!ts->inidle); |
925 | ||
926 | ts->inidle = 0; | |
927 | ||
928 | if (ts->idle_active || ts->tick_stopped) | |
eed3b9cf MS |
929 | now = ktime_get(); |
930 | ||
931 | if (ts->idle_active) | |
e8fcaa5c | 932 | tick_nohz_stop_idle(ts, now); |
6378ddb5 | 933 | |
2ac0d98f | 934 | if (ts->tick_stopped) { |
525705d1 | 935 | tick_nohz_restart_sched_tick(ts, now, 0); |
2ac0d98f | 936 | tick_nohz_account_idle_ticks(ts); |
6378ddb5 | 937 | } |
79bf2bb3 | 938 | |
79bf2bb3 TG |
939 | local_irq_enable(); |
940 | } | |
941 | ||
79bf2bb3 TG |
942 | /* |
943 | * The nohz low res interrupt handler | |
944 | */ | |
945 | static void tick_nohz_handler(struct clock_event_device *dev) | |
946 | { | |
22127e93 | 947 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
79bf2bb3 TG |
948 | struct pt_regs *regs = get_irq_regs(); |
949 | ktime_t now = ktime_get(); | |
950 | ||
951 | dev->next_event.tv64 = KTIME_MAX; | |
952 | ||
5bb96226 | 953 | tick_sched_do_timer(now); |
9e8f559b | 954 | tick_sched_handle(ts, regs); |
79bf2bb3 | 955 | |
b5e995e6 VK |
956 | /* No need to reprogram if we are running tickless */ |
957 | if (unlikely(ts->tick_stopped)) | |
958 | return; | |
959 | ||
0ff53d09 TG |
960 | hrtimer_forward(&ts->sched_timer, now, tick_period); |
961 | tick_program_event(hrtimer_get_expires(&ts->sched_timer), 1); | |
79bf2bb3 TG |
962 | } |
963 | ||
bc7a34b8 TG |
964 | static inline void tick_nohz_activate(struct tick_sched *ts, int mode) |
965 | { | |
966 | if (!tick_nohz_enabled) | |
967 | return; | |
968 | ts->nohz_mode = mode; | |
969 | /* One update is enough */ | |
970 | if (!test_and_set_bit(0, &tick_nohz_active)) | |
683be13a | 971 | timers_update_migration(true); |
bc7a34b8 TG |
972 | } |
973 | ||
79bf2bb3 TG |
974 | /** |
975 | * tick_nohz_switch_to_nohz - switch to nohz mode | |
976 | */ | |
977 | static void tick_nohz_switch_to_nohz(void) | |
978 | { | |
22127e93 | 979 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
79bf2bb3 TG |
980 | ktime_t next; |
981 | ||
27630532 | 982 | if (!tick_nohz_enabled) |
79bf2bb3 TG |
983 | return; |
984 | ||
6b442bc8 | 985 | if (tick_switch_to_oneshot(tick_nohz_handler)) |
79bf2bb3 | 986 | return; |
6b442bc8 | 987 | |
79bf2bb3 TG |
988 | /* |
989 | * Recycle the hrtimer in ts, so we can share the | |
990 | * hrtimer_forward with the highres code. | |
991 | */ | |
992 | hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); | |
993 | /* Get the next period */ | |
994 | next = tick_init_jiffy_update(); | |
995 | ||
0ff53d09 TG |
996 | hrtimer_forward_now(&ts->sched_timer, tick_period); |
997 | hrtimer_set_expires(&ts->sched_timer, next); | |
998 | tick_program_event(next, 1); | |
bc7a34b8 | 999 | tick_nohz_activate(ts, NOHZ_MODE_LOWRES); |
79bf2bb3 TG |
1000 | } |
1001 | ||
fb02fbc1 TG |
1002 | /* |
1003 | * When NOHZ is enabled and the tick is stopped, we need to kick the | |
1004 | * tick timer from irq_enter() so that the jiffies update is kept | |
1005 | * alive during long running softirqs. That's ugly as hell, but | |
1006 | * correctness is key even if we need to fix the offending softirq in | |
1007 | * the first place. | |
1008 | * | |
1009 | * Note, this is different to tick_nohz_restart. We just kick the | |
1010 | * timer and do not touch the other magic bits which need to be done | |
1011 | * when idle is left. | |
1012 | */ | |
e8fcaa5c | 1013 | static void tick_nohz_kick_tick(struct tick_sched *ts, ktime_t now) |
fb02fbc1 | 1014 | { |
ae99286b TG |
1015 | #if 0 |
1016 | /* Switch back to 2.6.27 behaviour */ | |
eed3b9cf | 1017 | ktime_t delta; |
fb02fbc1 | 1018 | |
c4bd822e TG |
1019 | /* |
1020 | * Do not touch the tick device, when the next expiry is either | |
1021 | * already reached or less/equal than the tick period. | |
1022 | */ | |
268a3dcf | 1023 | delta = ktime_sub(hrtimer_get_expires(&ts->sched_timer), now); |
c4bd822e TG |
1024 | if (delta.tv64 <= tick_period.tv64) |
1025 | return; | |
1026 | ||
1027 | tick_nohz_restart(ts, now); | |
ae99286b | 1028 | #endif |
fb02fbc1 TG |
1029 | } |
1030 | ||
5acac1be | 1031 | static inline void tick_nohz_irq_enter(void) |
eed3b9cf | 1032 | { |
4a32fea9 | 1033 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
eed3b9cf MS |
1034 | ktime_t now; |
1035 | ||
1036 | if (!ts->idle_active && !ts->tick_stopped) | |
1037 | return; | |
1038 | now = ktime_get(); | |
1039 | if (ts->idle_active) | |
e8fcaa5c | 1040 | tick_nohz_stop_idle(ts, now); |
eed3b9cf MS |
1041 | if (ts->tick_stopped) { |
1042 | tick_nohz_update_jiffies(now); | |
e8fcaa5c | 1043 | tick_nohz_kick_tick(ts, now); |
eed3b9cf MS |
1044 | } |
1045 | } | |
1046 | ||
79bf2bb3 TG |
1047 | #else |
1048 | ||
1049 | static inline void tick_nohz_switch_to_nohz(void) { } | |
5acac1be | 1050 | static inline void tick_nohz_irq_enter(void) { } |
bc7a34b8 | 1051 | static inline void tick_nohz_activate(struct tick_sched *ts, int mode) { } |
79bf2bb3 | 1052 | |
3451d024 | 1053 | #endif /* CONFIG_NO_HZ_COMMON */ |
79bf2bb3 | 1054 | |
719254fa TG |
1055 | /* |
1056 | * Called from irq_enter to notify about the possible interruption of idle() | |
1057 | */ | |
5acac1be | 1058 | void tick_irq_enter(void) |
719254fa | 1059 | { |
e8fcaa5c | 1060 | tick_check_oneshot_broadcast_this_cpu(); |
5acac1be | 1061 | tick_nohz_irq_enter(); |
719254fa TG |
1062 | } |
1063 | ||
79bf2bb3 TG |
1064 | /* |
1065 | * High resolution timer specific code | |
1066 | */ | |
1067 | #ifdef CONFIG_HIGH_RES_TIMERS | |
1068 | /* | |
4c9dc641 | 1069 | * We rearm the timer until we get disabled by the idle code. |
351f181f | 1070 | * Called with interrupts disabled. |
79bf2bb3 TG |
1071 | */ |
1072 | static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer) | |
1073 | { | |
1074 | struct tick_sched *ts = | |
1075 | container_of(timer, struct tick_sched, sched_timer); | |
79bf2bb3 TG |
1076 | struct pt_regs *regs = get_irq_regs(); |
1077 | ktime_t now = ktime_get(); | |
d3ed7824 | 1078 | |
5bb96226 | 1079 | tick_sched_do_timer(now); |
79bf2bb3 TG |
1080 | |
1081 | /* | |
1082 | * Do not call, when we are not in irq context and have | |
1083 | * no valid regs pointer | |
1084 | */ | |
9e8f559b FW |
1085 | if (regs) |
1086 | tick_sched_handle(ts, regs); | |
79bf2bb3 | 1087 | |
2a16fc93 VK |
1088 | /* No need to reprogram if we are in idle or full dynticks mode */ |
1089 | if (unlikely(ts->tick_stopped)) | |
1090 | return HRTIMER_NORESTART; | |
1091 | ||
79bf2bb3 TG |
1092 | hrtimer_forward(timer, now, tick_period); |
1093 | ||
1094 | return HRTIMER_RESTART; | |
1095 | } | |
1096 | ||
5307c955 MG |
1097 | static int sched_skew_tick; |
1098 | ||
62cf20b3 TG |
1099 | static int __init skew_tick(char *str) |
1100 | { | |
1101 | get_option(&str, &sched_skew_tick); | |
1102 | ||
1103 | return 0; | |
1104 | } | |
1105 | early_param("skew_tick", skew_tick); | |
1106 | ||
79bf2bb3 TG |
1107 | /** |
1108 | * tick_setup_sched_timer - setup the tick emulation timer | |
1109 | */ | |
1110 | void tick_setup_sched_timer(void) | |
1111 | { | |
22127e93 | 1112 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
79bf2bb3 TG |
1113 | ktime_t now = ktime_get(); |
1114 | ||
1115 | /* | |
1116 | * Emulate tick processing via per-CPU hrtimers: | |
1117 | */ | |
1118 | hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS); | |
1119 | ts->sched_timer.function = tick_sched_timer; | |
79bf2bb3 | 1120 | |
3704540b | 1121 | /* Get the next period (per cpu) */ |
cc584b21 | 1122 | hrtimer_set_expires(&ts->sched_timer, tick_init_jiffy_update()); |
79bf2bb3 | 1123 | |
9c3f9e28 | 1124 | /* Offset the tick to avert jiffies_lock contention. */ |
5307c955 MG |
1125 | if (sched_skew_tick) { |
1126 | u64 offset = ktime_to_ns(tick_period) >> 1; | |
1127 | do_div(offset, num_possible_cpus()); | |
1128 | offset *= smp_processor_id(); | |
1129 | hrtimer_add_expires_ns(&ts->sched_timer, offset); | |
1130 | } | |
1131 | ||
afc08b15 TG |
1132 | hrtimer_forward(&ts->sched_timer, now, tick_period); |
1133 | hrtimer_start_expires(&ts->sched_timer, HRTIMER_MODE_ABS_PINNED); | |
bc7a34b8 | 1134 | tick_nohz_activate(ts, NOHZ_MODE_HIGHRES); |
79bf2bb3 | 1135 | } |
3c4fbe5e | 1136 | #endif /* HIGH_RES_TIMERS */ |
79bf2bb3 | 1137 | |
3451d024 | 1138 | #if defined CONFIG_NO_HZ_COMMON || defined CONFIG_HIGH_RES_TIMERS |
79bf2bb3 TG |
1139 | void tick_cancel_sched_timer(int cpu) |
1140 | { | |
1141 | struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu); | |
1142 | ||
3c4fbe5e | 1143 | # ifdef CONFIG_HIGH_RES_TIMERS |
79bf2bb3 TG |
1144 | if (ts->sched_timer.base) |
1145 | hrtimer_cancel(&ts->sched_timer); | |
3c4fbe5e | 1146 | # endif |
a7901766 | 1147 | |
4b0c0f29 | 1148 | memset(ts, 0, sizeof(*ts)); |
79bf2bb3 | 1149 | } |
3c4fbe5e | 1150 | #endif |
79bf2bb3 TG |
1151 | |
1152 | /** | |
1153 | * Async notification about clocksource changes | |
1154 | */ | |
1155 | void tick_clock_notify(void) | |
1156 | { | |
1157 | int cpu; | |
1158 | ||
1159 | for_each_possible_cpu(cpu) | |
1160 | set_bit(0, &per_cpu(tick_cpu_sched, cpu).check_clocks); | |
1161 | } | |
1162 | ||
1163 | /* | |
1164 | * Async notification about clock event changes | |
1165 | */ | |
1166 | void tick_oneshot_notify(void) | |
1167 | { | |
22127e93 | 1168 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
79bf2bb3 TG |
1169 | |
1170 | set_bit(0, &ts->check_clocks); | |
1171 | } | |
1172 | ||
1173 | /** | |
1174 | * Check, if a change happened, which makes oneshot possible. | |
1175 | * | |
1176 | * Called cyclic from the hrtimer softirq (driven by the timer | |
1177 | * softirq) allow_nohz signals, that we can switch into low-res nohz | |
1178 | * mode, because high resolution timers are disabled (either compile | |
6b442bc8 | 1179 | * or runtime). Called with interrupts disabled. |
79bf2bb3 TG |
1180 | */ |
1181 | int tick_check_oneshot_change(int allow_nohz) | |
1182 | { | |
22127e93 | 1183 | struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched); |
79bf2bb3 TG |
1184 | |
1185 | if (!test_and_clear_bit(0, &ts->check_clocks)) | |
1186 | return 0; | |
1187 | ||
1188 | if (ts->nohz_mode != NOHZ_MODE_INACTIVE) | |
1189 | return 0; | |
1190 | ||
cf4fc6cb | 1191 | if (!timekeeping_valid_for_hres() || !tick_is_oneshot_available()) |
79bf2bb3 TG |
1192 | return 0; |
1193 | ||
1194 | if (!allow_nohz) | |
1195 | return 1; | |
1196 | ||
1197 | tick_nohz_switch_to_nohz(); | |
1198 | return 0; | |
1199 | } |