forked from luck/tmp_suning_uos_patched
289f480af8
add /proc/timer_list, which prints all currently pending (high-res) timers, all clock-event sources and their parameters in a human-readable form. Sample output: Timer List Version: v0.1 HRTIMER_MAX_CLOCK_BASES: 2 now at 4246046273872 nsecs cpu: 0 clock 0: .index: 0 .resolution: 1 nsecs .get_time: ktime_get_real .offset: 1273998312645738432 nsecs active timers: clock 1: .index: 1 .resolution: 1 nsecs .get_time: ktime_get .offset: 0 nsecs active timers: #0: <f5a90ec8>, hrtimer_sched_tick, hrtimer_stop_sched_tick, swapper/0 # expires at 4246432689566 nsecs [in 386415694 nsecs] #1: <f5a90ec8>, hrtimer_wakeup, do_nanosleep, pcscd/2050 # expires at 4247018194689 nsecs [in 971920817 nsecs] #2: <f5a90ec8>, hrtimer_wakeup, do_nanosleep, irqbalance/1909 # expires at 4247351358392 nsecs [in 1305084520 nsecs] #3: <f5a90ec8>, hrtimer_wakeup, do_nanosleep, crond/2157 # expires at 4249097614968 nsecs [in 3051341096 nsecs] #4: <f5a90ec8>, it_real_fn, do_setitimer, syslogd/1888 # expires at 4251329900926 nsecs [in 5283627054 nsecs] .expires_next : 4246432689566 nsecs .hres_active : 1 .check_clocks : 0 .nr_events : 31306 .idle_tick : 4246020791890 nsecs .tick_stopped : 1 .idle_jiffies : 986504 .idle_calls : 40700 .idle_sleeps : 36014 .idle_entrytime : 4246019418883 nsecs .idle_sleeptime : 4178181972709 nsecs cpu: 1 clock 0: .index: 0 .resolution: 1 nsecs .get_time: ktime_get_real .offset: 1273998312645738432 nsecs active timers: clock 1: .index: 1 .resolution: 1 nsecs .get_time: ktime_get .offset: 0 nsecs active timers: #0: <f5a90ec8>, hrtimer_sched_tick, hrtimer_restart_sched_tick, swapper/0 # expires at 4246050084568 nsecs [in 3810696 nsecs] #1: <f5a90ec8>, hrtimer_wakeup, do_nanosleep, atd/2227 # expires at 4261010635003 nsecs [in 14964361131 nsecs] #2: <f5a90ec8>, hrtimer_wakeup, do_nanosleep, smartd/2332 # expires at 5469485798970 nsecs [in 1223439525098 nsecs] .expires_next : 4246050084568 nsecs .hres_active : 1 .check_clocks : 0 .nr_events : 24043 .idle_tick : 4246046084568 nsecs .tick_stopped : 0 .idle_jiffies : 986510 .idle_calls : 26360 .idle_sleeps : 22551 .idle_entrytime : 4246043874339 nsecs .idle_sleeptime : 4170763761184 nsecs tick_broadcast_mask: 00000003 event_broadcast_mask: 00000001 CPU#0's local event device: Clock Event Device: lapic capabilities: 0000000e max_delta_ns: 807385544 min_delta_ns: 1443 mult: 44624025 shift: 32 set_next_event: lapic_next_event set_mode: lapic_timer_setup event_handler: hrtimer_interrupt .installed: 1 .expires: 4246432689566 nsecs CPU#1's local event device: Clock Event Device: lapic capabilities: 0000000e max_delta_ns: 807385544 min_delta_ns: 1443 mult: 44624025 shift: 32 set_next_event: lapic_next_event set_mode: lapic_timer_setup event_handler: hrtimer_interrupt .installed: 1 .expires: 4246050084568 nsecs Clock Event Device: hpet capabilities: 00000007 max_delta_ns: 2147483647 min_delta_ns: 3352 mult: 61496110 shift: 32 set_next_event: hpet_next_event set_mode: hpet_set_mode event_handler: handle_nextevt_broadcast Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: john stultz <johnstul@us.ibm.com> Cc: Roman Zippel <zippel@linux-m68k.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
564 lines
14 KiB
C
564 lines
14 KiB
C
/*
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* linux/kernel/time/tick-sched.c
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*
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* Copyright(C) 2005-2006, Thomas Gleixner <tglx@linutronix.de>
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* Copyright(C) 2005-2007, Red Hat, Inc., Ingo Molnar
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* Copyright(C) 2006-2007 Timesys Corp., Thomas Gleixner
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*
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* No idle tick implementation for low and high resolution timers
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*
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* Started by: Thomas Gleixner and Ingo Molnar
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*
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* For licencing details see kernel-base/COPYING
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*/
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#include <linux/cpu.h>
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#include <linux/err.h>
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#include <linux/hrtimer.h>
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#include <linux/interrupt.h>
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#include <linux/kernel_stat.h>
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#include <linux/percpu.h>
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#include <linux/profile.h>
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#include <linux/sched.h>
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#include <linux/tick.h>
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#include "tick-internal.h"
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/*
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* Per cpu nohz control structure
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*/
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static DEFINE_PER_CPU(struct tick_sched, tick_cpu_sched);
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/*
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* The time, when the last jiffy update happened. Protected by xtime_lock.
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*/
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static ktime_t last_jiffies_update;
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struct tick_sched *tick_get_tick_sched(int cpu)
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{
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return &per_cpu(tick_cpu_sched, cpu);
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}
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/*
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* Must be called with interrupts disabled !
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*/
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static void tick_do_update_jiffies64(ktime_t now)
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{
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unsigned long ticks = 0;
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ktime_t delta;
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/* Reevalute with xtime_lock held */
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write_seqlock(&xtime_lock);
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delta = ktime_sub(now, last_jiffies_update);
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if (delta.tv64 >= tick_period.tv64) {
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delta = ktime_sub(delta, tick_period);
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last_jiffies_update = ktime_add(last_jiffies_update,
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tick_period);
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/* Slow path for long timeouts */
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if (unlikely(delta.tv64 >= tick_period.tv64)) {
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s64 incr = ktime_to_ns(tick_period);
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ticks = ktime_divns(delta, incr);
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last_jiffies_update = ktime_add_ns(last_jiffies_update,
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incr * ticks);
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}
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do_timer(++ticks);
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}
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write_sequnlock(&xtime_lock);
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}
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/*
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* Initialize and return retrieve the jiffies update.
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*/
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static ktime_t tick_init_jiffy_update(void)
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{
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ktime_t period;
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write_seqlock(&xtime_lock);
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/* Did we start the jiffies update yet ? */
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if (last_jiffies_update.tv64 == 0)
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last_jiffies_update = tick_next_period;
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period = last_jiffies_update;
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write_sequnlock(&xtime_lock);
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return period;
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}
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/*
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* NOHZ - aka dynamic tick functionality
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*/
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#ifdef CONFIG_NO_HZ
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/*
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* NO HZ enabled ?
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*/
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static int tick_nohz_enabled __read_mostly = 1;
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/*
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* Enable / Disable tickless mode
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*/
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static int __init setup_tick_nohz(char *str)
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{
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if (!strcmp(str, "off"))
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tick_nohz_enabled = 0;
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else if (!strcmp(str, "on"))
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tick_nohz_enabled = 1;
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else
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return 0;
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return 1;
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}
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__setup("nohz=", setup_tick_nohz);
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/**
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* tick_nohz_update_jiffies - update jiffies when idle was interrupted
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*
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* Called from interrupt entry when the CPU was idle
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*
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* In case the sched_tick was stopped on this CPU, we have to check if jiffies
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* must be updated. Otherwise an interrupt handler could use a stale jiffy
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* value. We do this unconditionally on any cpu, as we don't know whether the
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* cpu, which has the update task assigned is in a long sleep.
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*/
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void tick_nohz_update_jiffies(void)
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{
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int cpu = smp_processor_id();
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struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
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unsigned long flags;
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ktime_t now;
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if (!ts->tick_stopped)
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return;
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cpu_clear(cpu, nohz_cpu_mask);
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now = ktime_get();
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local_irq_save(flags);
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tick_do_update_jiffies64(now);
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local_irq_restore(flags);
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}
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/**
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* tick_nohz_stop_sched_tick - stop the idle tick from the idle task
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*
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* When the next event is more than a tick into the future, stop the idle tick
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* Called either from the idle loop or from irq_exit() when an idle period was
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* just interrupted by an interrupt which did not cause a reschedule.
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*/
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void tick_nohz_stop_sched_tick(void)
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{
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unsigned long seq, last_jiffies, next_jiffies, delta_jiffies, flags;
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struct tick_sched *ts;
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ktime_t last_update, expires, now, delta;
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int cpu;
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local_irq_save(flags);
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cpu = smp_processor_id();
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ts = &per_cpu(tick_cpu_sched, cpu);
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if (unlikely(ts->nohz_mode == NOHZ_MODE_INACTIVE))
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goto end;
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if (need_resched())
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goto end;
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cpu = smp_processor_id();
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BUG_ON(local_softirq_pending());
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now = ktime_get();
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/*
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* When called from irq_exit we need to account the idle sleep time
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* correctly.
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*/
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if (ts->tick_stopped) {
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delta = ktime_sub(now, ts->idle_entrytime);
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ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta);
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}
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ts->idle_entrytime = now;
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ts->idle_calls++;
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/* Read jiffies and the time when jiffies were updated last */
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do {
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seq = read_seqbegin(&xtime_lock);
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last_update = last_jiffies_update;
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last_jiffies = jiffies;
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} while (read_seqretry(&xtime_lock, seq));
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/* Get the next timer wheel timer */
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next_jiffies = get_next_timer_interrupt(last_jiffies);
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delta_jiffies = next_jiffies - last_jiffies;
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/*
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* Do not stop the tick, if we are only one off
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* or if the cpu is required for rcu
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*/
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if (!ts->tick_stopped && (delta_jiffies == 1 || rcu_needs_cpu(cpu)))
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goto out;
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/* Schedule the tick, if we are at least one jiffie off */
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if ((long)delta_jiffies >= 1) {
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if (rcu_needs_cpu(cpu))
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delta_jiffies = 1;
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else
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cpu_set(cpu, nohz_cpu_mask);
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/*
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* nohz_stop_sched_tick can be called several times before
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* the nohz_restart_sched_tick is called. This happens when
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* interrupts arrive which do not cause a reschedule. In the
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* first call we save the current tick time, so we can restart
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* the scheduler tick in nohz_restart_sched_tick.
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*/
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if (!ts->tick_stopped) {
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ts->idle_tick = ts->sched_timer.expires;
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ts->tick_stopped = 1;
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ts->idle_jiffies = last_jiffies;
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}
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/*
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* calculate the expiry time for the next timer wheel
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* timer
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*/
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expires = ktime_add_ns(last_update, tick_period.tv64 *
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delta_jiffies);
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ts->idle_expires = expires;
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ts->idle_sleeps++;
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if (ts->nohz_mode == NOHZ_MODE_HIGHRES) {
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hrtimer_start(&ts->sched_timer, expires,
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HRTIMER_MODE_ABS);
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/* Check, if the timer was already in the past */
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if (hrtimer_active(&ts->sched_timer))
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goto out;
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} else if(!tick_program_event(expires, 0))
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goto out;
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/*
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* We are past the event already. So we crossed a
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* jiffie boundary. Update jiffies and raise the
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* softirq.
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*/
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tick_do_update_jiffies64(ktime_get());
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cpu_clear(cpu, nohz_cpu_mask);
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}
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raise_softirq_irqoff(TIMER_SOFTIRQ);
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out:
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ts->next_jiffies = next_jiffies;
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ts->last_jiffies = last_jiffies;
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end:
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local_irq_restore(flags);
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}
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/**
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* nohz_restart_sched_tick - restart the idle tick from the idle task
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*
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* Restart the idle tick when the CPU is woken up from idle
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*/
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void tick_nohz_restart_sched_tick(void)
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{
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int cpu = smp_processor_id();
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struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
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unsigned long ticks;
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ktime_t now, delta;
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if (!ts->tick_stopped)
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return;
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/* Update jiffies first */
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now = ktime_get();
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local_irq_disable();
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tick_do_update_jiffies64(now);
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cpu_clear(cpu, nohz_cpu_mask);
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/* Account the idle time */
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delta = ktime_sub(now, ts->idle_entrytime);
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ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta);
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/*
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* We stopped the tick in idle. Update process times would miss the
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* time we slept as update_process_times does only a 1 tick
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* accounting. Enforce that this is accounted to idle !
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*/
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ticks = jiffies - ts->idle_jiffies;
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/*
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* We might be one off. Do not randomly account a huge number of ticks!
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*/
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if (ticks && ticks < LONG_MAX) {
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add_preempt_count(HARDIRQ_OFFSET);
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account_system_time(current, HARDIRQ_OFFSET,
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jiffies_to_cputime(ticks));
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sub_preempt_count(HARDIRQ_OFFSET);
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}
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/*
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* Cancel the scheduled timer and restore the tick
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*/
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ts->tick_stopped = 0;
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hrtimer_cancel(&ts->sched_timer);
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ts->sched_timer.expires = ts->idle_tick;
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while (1) {
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/* Forward the time to expire in the future */
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hrtimer_forward(&ts->sched_timer, now, tick_period);
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if (ts->nohz_mode == NOHZ_MODE_HIGHRES) {
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hrtimer_start(&ts->sched_timer,
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ts->sched_timer.expires,
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HRTIMER_MODE_ABS);
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/* Check, if the timer was already in the past */
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if (hrtimer_active(&ts->sched_timer))
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break;
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} else {
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if (!tick_program_event(ts->sched_timer.expires, 0))
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break;
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}
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/* Update jiffies and reread time */
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tick_do_update_jiffies64(now);
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now = ktime_get();
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}
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local_irq_enable();
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}
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static int tick_nohz_reprogram(struct tick_sched *ts, ktime_t now)
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{
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hrtimer_forward(&ts->sched_timer, now, tick_period);
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return tick_program_event(ts->sched_timer.expires, 0);
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}
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/*
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* The nohz low res interrupt handler
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*/
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static void tick_nohz_handler(struct clock_event_device *dev)
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{
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struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
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struct pt_regs *regs = get_irq_regs();
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ktime_t now = ktime_get();
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dev->next_event.tv64 = KTIME_MAX;
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/* Check, if the jiffies need an update */
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tick_do_update_jiffies64(now);
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/*
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* When we are idle and the tick is stopped, we have to touch
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* the watchdog as we might not schedule for a really long
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* time. This happens on complete idle SMP systems while
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* waiting on the login prompt. We also increment the "start
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* of idle" jiffy stamp so the idle accounting adjustment we
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* do when we go busy again does not account too much ticks.
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*/
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if (ts->tick_stopped) {
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touch_softlockup_watchdog();
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ts->idle_jiffies++;
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}
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update_process_times(user_mode(regs));
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profile_tick(CPU_PROFILING);
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/* Do not restart, when we are in the idle loop */
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if (ts->tick_stopped)
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return;
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while (tick_nohz_reprogram(ts, now)) {
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now = ktime_get();
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tick_do_update_jiffies64(now);
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}
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}
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/**
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* tick_nohz_switch_to_nohz - switch to nohz mode
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*/
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static void tick_nohz_switch_to_nohz(void)
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{
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struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
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ktime_t next;
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if (!tick_nohz_enabled)
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return;
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local_irq_disable();
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if (tick_switch_to_oneshot(tick_nohz_handler)) {
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local_irq_enable();
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return;
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}
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ts->nohz_mode = NOHZ_MODE_LOWRES;
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/*
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* Recycle the hrtimer in ts, so we can share the
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* hrtimer_forward with the highres code.
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*/
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hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
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/* Get the next period */
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next = tick_init_jiffy_update();
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for (;;) {
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ts->sched_timer.expires = next;
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if (!tick_program_event(next, 0))
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break;
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next = ktime_add(next, tick_period);
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}
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local_irq_enable();
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printk(KERN_INFO "Switched to NOHz mode on CPU #%d\n",
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smp_processor_id());
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}
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#else
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static inline void tick_nohz_switch_to_nohz(void) { }
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#endif /* NO_HZ */
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/*
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* High resolution timer specific code
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*/
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#ifdef CONFIG_HIGH_RES_TIMERS
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/*
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* We rearm the timer until we get disabled by the idle code
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* Called with interrupts disabled and timer->base->cpu_base->lock held.
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*/
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static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer)
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{
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struct tick_sched *ts =
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container_of(timer, struct tick_sched, sched_timer);
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struct hrtimer_cpu_base *base = timer->base->cpu_base;
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struct pt_regs *regs = get_irq_regs();
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ktime_t now = ktime_get();
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/* Check, if the jiffies need an update */
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tick_do_update_jiffies64(now);
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/*
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* Do not call, when we are not in irq context and have
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* no valid regs pointer
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*/
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if (regs) {
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/*
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* When we are idle and the tick is stopped, we have to touch
|
|
* the watchdog as we might not schedule for a really long
|
|
* time. This happens on complete idle SMP systems while
|
|
* waiting on the login prompt. We also increment the "start of
|
|
* idle" jiffy stamp so the idle accounting adjustment we do
|
|
* when we go busy again does not account too much ticks.
|
|
*/
|
|
if (ts->tick_stopped) {
|
|
touch_softlockup_watchdog();
|
|
ts->idle_jiffies++;
|
|
}
|
|
/*
|
|
* update_process_times() might take tasklist_lock, hence
|
|
* drop the base lock. sched-tick hrtimers are per-CPU and
|
|
* never accessible by userspace APIs, so this is safe to do.
|
|
*/
|
|
spin_unlock(&base->lock);
|
|
update_process_times(user_mode(regs));
|
|
profile_tick(CPU_PROFILING);
|
|
spin_lock(&base->lock);
|
|
}
|
|
|
|
/* Do not restart, when we are in the idle loop */
|
|
if (ts->tick_stopped)
|
|
return HRTIMER_NORESTART;
|
|
|
|
hrtimer_forward(timer, now, tick_period);
|
|
|
|
return HRTIMER_RESTART;
|
|
}
|
|
|
|
/**
|
|
* tick_setup_sched_timer - setup the tick emulation timer
|
|
*/
|
|
void tick_setup_sched_timer(void)
|
|
{
|
|
struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
|
|
ktime_t now = ktime_get();
|
|
|
|
/*
|
|
* Emulate tick processing via per-CPU hrtimers:
|
|
*/
|
|
hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
|
|
ts->sched_timer.function = tick_sched_timer;
|
|
ts->sched_timer.cb_mode = HRTIMER_CB_IRQSAFE_NO_SOFTIRQ;
|
|
|
|
/* Get the next period */
|
|
ts->sched_timer.expires = tick_init_jiffy_update();
|
|
|
|
for (;;) {
|
|
hrtimer_forward(&ts->sched_timer, now, tick_period);
|
|
hrtimer_start(&ts->sched_timer, ts->sched_timer.expires,
|
|
HRTIMER_MODE_ABS);
|
|
/* Check, if the timer was already in the past */
|
|
if (hrtimer_active(&ts->sched_timer))
|
|
break;
|
|
now = ktime_get();
|
|
}
|
|
|
|
#ifdef CONFIG_NO_HZ
|
|
if (tick_nohz_enabled)
|
|
ts->nohz_mode = NOHZ_MODE_HIGHRES;
|
|
#endif
|
|
}
|
|
|
|
void tick_cancel_sched_timer(int cpu)
|
|
{
|
|
struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
|
|
|
|
if (ts->sched_timer.base)
|
|
hrtimer_cancel(&ts->sched_timer);
|
|
ts->tick_stopped = 0;
|
|
ts->nohz_mode = NOHZ_MODE_INACTIVE;
|
|
}
|
|
#endif /* HIGH_RES_TIMERS */
|
|
|
|
/**
|
|
* Async notification about clocksource changes
|
|
*/
|
|
void tick_clock_notify(void)
|
|
{
|
|
int cpu;
|
|
|
|
for_each_possible_cpu(cpu)
|
|
set_bit(0, &per_cpu(tick_cpu_sched, cpu).check_clocks);
|
|
}
|
|
|
|
/*
|
|
* Async notification about clock event changes
|
|
*/
|
|
void tick_oneshot_notify(void)
|
|
{
|
|
struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
|
|
|
|
set_bit(0, &ts->check_clocks);
|
|
}
|
|
|
|
/**
|
|
* Check, if a change happened, which makes oneshot possible.
|
|
*
|
|
* Called cyclic from the hrtimer softirq (driven by the timer
|
|
* softirq) allow_nohz signals, that we can switch into low-res nohz
|
|
* mode, because high resolution timers are disabled (either compile
|
|
* or runtime).
|
|
*/
|
|
int tick_check_oneshot_change(int allow_nohz)
|
|
{
|
|
struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
|
|
|
|
if (!test_and_clear_bit(0, &ts->check_clocks))
|
|
return 0;
|
|
|
|
if (ts->nohz_mode != NOHZ_MODE_INACTIVE)
|
|
return 0;
|
|
|
|
if (!timekeeping_is_continuous() || !tick_is_oneshot_available())
|
|
return 0;
|
|
|
|
if (!allow_nohz)
|
|
return 1;
|
|
|
|
tick_nohz_switch_to_nohz();
|
|
return 0;
|
|
}
|