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![Linus Torvalds](/assets/img/avatar_default.png)
* 'timers-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: timers, init: Limit the number of per cpu calibration bootup messages posix-cpu-timers: optimize and document timer_create callback clockevents: Add missing include to pacify sparse x86: vmiclock: Fix printk format x86: Fix printk format due to variable type change sparc: fix printk for change of variable type clocksource/events: Fix fallout of generic code changes nohz: Allow 32-bit machines to sleep for more than 2.15 seconds nohz: Track last do_timer() cpu nohz: Prevent clocksource wrapping during idle nohz: Type cast printk argument mips: Use generic mult/shift factor calculation for clocks clocksource: Provide a generic mult/shift factor calculation clockevents: Use u32 for mult and shift factors nohz: Introduce arch_needs_cpu nohz: Reuse ktime in sub-functions of tick_check_idle. time: Remove xtime_cache time: Implement logarithmic time accumulation
823 lines
21 KiB
C
823 lines
21 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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* Distribute under GPLv2.
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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 <linux/module.h>
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#include <asm/irq_regs.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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/*
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* Do a quick check without holding xtime_lock:
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*/
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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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return;
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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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/* Keep the tick_next_period variable up to date */
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tick_next_period = ktime_add(last_jiffies_update, tick_period);
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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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static void tick_nohz_update_jiffies(ktime_t now)
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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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cpumask_clear_cpu(cpu, nohz_cpu_mask);
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ts->idle_waketime = now;
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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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touch_softlockup_watchdog();
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}
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static void tick_nohz_stop_idle(int cpu, ktime_t now)
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{
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struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
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ktime_t delta;
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delta = ktime_sub(now, ts->idle_entrytime);
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ts->idle_lastupdate = now;
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ts->idle_sleeptime = ktime_add(ts->idle_sleeptime, delta);
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ts->idle_active = 0;
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sched_clock_idle_wakeup_event(0);
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}
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static ktime_t tick_nohz_start_idle(struct tick_sched *ts)
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{
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ktime_t now, delta;
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now = ktime_get();
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if (ts->idle_active) {
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delta = ktime_sub(now, ts->idle_entrytime);
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ts->idle_lastupdate = now;
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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_active = 1;
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sched_clock_idle_sleep_event();
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return now;
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}
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u64 get_cpu_idle_time_us(int cpu, u64 *last_update_time)
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{
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struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
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if (!tick_nohz_enabled)
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return -1;
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if (ts->idle_active)
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*last_update_time = ktime_to_us(ts->idle_lastupdate);
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else
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*last_update_time = ktime_to_us(ktime_get());
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return ktime_to_us(ts->idle_sleeptime);
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}
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EXPORT_SYMBOL_GPL(get_cpu_idle_time_us);
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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(int inidle)
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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;
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struct clock_event_device *dev = __get_cpu_var(tick_cpu_device).evtdev;
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u64 time_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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/*
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* Call to tick_nohz_start_idle stops the last_update_time from being
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* updated. Thus, it must not be called in the event we are called from
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* irq_exit() with the prior state different than idle.
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*/
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if (!inidle && !ts->inidle)
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goto end;
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/*
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* Set ts->inidle unconditionally. Even if the system did not
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* switch to NOHZ mode the cpu frequency governers rely on the
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* update of the idle time accounting in tick_nohz_start_idle().
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*/
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ts->inidle = 1;
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now = tick_nohz_start_idle(ts);
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/*
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* If this cpu is offline and it is the one which updates
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* jiffies, then give up the assignment and let it be taken by
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* the cpu which runs the tick timer next. If we don't drop
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* this here the jiffies might be stale and do_timer() never
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* invoked.
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*/
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if (unlikely(!cpu_online(cpu))) {
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if (cpu == tick_do_timer_cpu)
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tick_do_timer_cpu = TICK_DO_TIMER_NONE;
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}
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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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if (unlikely(local_softirq_pending() && cpu_online(cpu))) {
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static int ratelimit;
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if (ratelimit < 10) {
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printk(KERN_ERR "NOHZ: local_softirq_pending %02x\n",
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(unsigned int) local_softirq_pending());
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ratelimit++;
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}
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goto end;
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}
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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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time_delta = timekeeping_max_deferment();
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} while (read_seqretry(&xtime_lock, seq));
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if (rcu_needs_cpu(cpu) || printk_needs_cpu(cpu) ||
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arch_needs_cpu(cpu)) {
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next_jiffies = last_jiffies + 1;
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delta_jiffies = 1;
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} else {
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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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/*
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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)
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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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/*
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* If this cpu is the one which updates jiffies, then
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* give up the assignment and let it be taken by the
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* cpu which runs the tick timer next, which might be
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* this cpu as well. If we don't drop this here the
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* jiffies might be stale and do_timer() never
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* invoked. Keep track of the fact that it was the one
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* which had the do_timer() duty last. If this cpu is
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* the one which had the do_timer() duty last, we
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* limit the sleep time to the timekeeping
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* max_deferement value which we retrieved
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* above. Otherwise we can sleep as long as we want.
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*/
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if (cpu == tick_do_timer_cpu) {
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tick_do_timer_cpu = TICK_DO_TIMER_NONE;
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ts->do_timer_last = 1;
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} else if (tick_do_timer_cpu != TICK_DO_TIMER_NONE) {
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time_delta = KTIME_MAX;
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ts->do_timer_last = 0;
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} else if (!ts->do_timer_last) {
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time_delta = KTIME_MAX;
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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. delta_jiffies >= NEXT_TIMER_MAX_DELTA signals
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* that there is no timer pending or at least extremely
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* far into the future (12 days for HZ=1000). In this
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* case we set the expiry to the end of time.
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*/
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if (likely(delta_jiffies < NEXT_TIMER_MAX_DELTA)) {
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/*
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* Calculate the time delta for the next timer event.
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* If the time delta exceeds the maximum time delta
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* permitted by the current clocksource then adjust
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* the time delta accordingly to ensure the
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* clocksource does not wrap.
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*/
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time_delta = min_t(u64, time_delta,
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tick_period.tv64 * delta_jiffies);
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}
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if (time_delta < KTIME_MAX)
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expires = ktime_add_ns(last_update, time_delta);
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else
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expires.tv64 = KTIME_MAX;
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if (delta_jiffies > 1)
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cpumask_set_cpu(cpu, nohz_cpu_mask);
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/* Skip reprogram of event if its not changed */
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if (ts->tick_stopped && ktime_equal(expires, dev->next_event))
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goto out;
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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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if (select_nohz_load_balancer(1)) {
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/*
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* sched tick not stopped!
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*/
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cpumask_clear_cpu(cpu, nohz_cpu_mask);
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goto out;
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}
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ts->idle_tick = hrtimer_get_expires(&ts->sched_timer);
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ts->tick_stopped = 1;
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ts->idle_jiffies = last_jiffies;
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rcu_enter_nohz();
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}
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ts->idle_sleeps++;
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/* Mark expires */
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ts->idle_expires = expires;
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/*
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* If the expiration time == KTIME_MAX, then
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* in this case we simply stop the tick timer.
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*/
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if (unlikely(expires.tv64 == KTIME_MAX)) {
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if (ts->nohz_mode == NOHZ_MODE_HIGHRES)
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hrtimer_cancel(&ts->sched_timer);
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goto out;
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}
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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_PINNED);
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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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cpumask_clear_cpu(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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ts->sleep_length = ktime_sub(dev->next_event, now);
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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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/**
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* tick_nohz_get_sleep_length - return the length of the current sleep
|
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*
|
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* Called from power state control code with interrupts disabled
|
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*/
|
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ktime_t tick_nohz_get_sleep_length(void)
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{
|
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struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
|
|
|
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return ts->sleep_length;
|
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}
|
|
|
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static void tick_nohz_restart(struct tick_sched *ts, ktime_t now)
|
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{
|
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hrtimer_cancel(&ts->sched_timer);
|
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hrtimer_set_expires(&ts->sched_timer, 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_expires(&ts->sched_timer,
|
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HRTIMER_MODE_ABS_PINNED);
|
|
/* Check, if the timer was already in the past */
|
|
if (hrtimer_active(&ts->sched_timer))
|
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break;
|
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} else {
|
|
if (!tick_program_event(
|
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hrtimer_get_expires(&ts->sched_timer), 0))
|
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break;
|
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}
|
|
/* Update jiffies and reread time */
|
|
tick_do_update_jiffies64(now);
|
|
now = ktime_get();
|
|
}
|
|
}
|
|
|
|
/**
|
|
* tick_nohz_restart_sched_tick - restart the idle tick from the idle task
|
|
*
|
|
* Restart the idle tick when the CPU is woken up from idle
|
|
*/
|
|
void tick_nohz_restart_sched_tick(void)
|
|
{
|
|
int cpu = smp_processor_id();
|
|
struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
|
|
#ifndef CONFIG_VIRT_CPU_ACCOUNTING
|
|
unsigned long ticks;
|
|
#endif
|
|
ktime_t now;
|
|
|
|
local_irq_disable();
|
|
if (ts->idle_active || (ts->inidle && ts->tick_stopped))
|
|
now = ktime_get();
|
|
|
|
if (ts->idle_active)
|
|
tick_nohz_stop_idle(cpu, now);
|
|
|
|
if (!ts->inidle || !ts->tick_stopped) {
|
|
ts->inidle = 0;
|
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local_irq_enable();
|
|
return;
|
|
}
|
|
|
|
ts->inidle = 0;
|
|
|
|
rcu_exit_nohz();
|
|
|
|
/* Update jiffies first */
|
|
select_nohz_load_balancer(0);
|
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tick_do_update_jiffies64(now);
|
|
cpumask_clear_cpu(cpu, nohz_cpu_mask);
|
|
|
|
#ifndef CONFIG_VIRT_CPU_ACCOUNTING
|
|
/*
|
|
* We stopped the tick in idle. Update process times would miss the
|
|
* time we slept as update_process_times does only a 1 tick
|
|
* accounting. Enforce that this is accounted to idle !
|
|
*/
|
|
ticks = jiffies - ts->idle_jiffies;
|
|
/*
|
|
* We might be one off. Do not randomly account a huge number of ticks!
|
|
*/
|
|
if (ticks && ticks < LONG_MAX)
|
|
account_idle_ticks(ticks);
|
|
#endif
|
|
|
|
touch_softlockup_watchdog();
|
|
/*
|
|
* Cancel the scheduled timer and restore the tick
|
|
*/
|
|
ts->tick_stopped = 0;
|
|
ts->idle_exittime = now;
|
|
|
|
tick_nohz_restart(ts, now);
|
|
|
|
local_irq_enable();
|
|
}
|
|
|
|
static int tick_nohz_reprogram(struct tick_sched *ts, ktime_t now)
|
|
{
|
|
hrtimer_forward(&ts->sched_timer, now, tick_period);
|
|
return tick_program_event(hrtimer_get_expires(&ts->sched_timer), 0);
|
|
}
|
|
|
|
/*
|
|
* The nohz low res interrupt handler
|
|
*/
|
|
static void tick_nohz_handler(struct clock_event_device *dev)
|
|
{
|
|
struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
|
|
struct pt_regs *regs = get_irq_regs();
|
|
int cpu = smp_processor_id();
|
|
ktime_t now = ktime_get();
|
|
|
|
dev->next_event.tv64 = KTIME_MAX;
|
|
|
|
/*
|
|
* Check if the do_timer duty was dropped. We don't care about
|
|
* concurrency: This happens only when the cpu in charge went
|
|
* into a long sleep. If two cpus happen to assign themself to
|
|
* this duty, then the jiffies update is still serialized by
|
|
* xtime_lock.
|
|
*/
|
|
if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE))
|
|
tick_do_timer_cpu = cpu;
|
|
|
|
/* Check, if the jiffies need an update */
|
|
if (tick_do_timer_cpu == cpu)
|
|
tick_do_update_jiffies64(now);
|
|
|
|
/*
|
|
* 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(user_mode(regs));
|
|
profile_tick(CPU_PROFILING);
|
|
|
|
while (tick_nohz_reprogram(ts, now)) {
|
|
now = ktime_get();
|
|
tick_do_update_jiffies64(now);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* tick_nohz_switch_to_nohz - switch to nohz mode
|
|
*/
|
|
static void tick_nohz_switch_to_nohz(void)
|
|
{
|
|
struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched);
|
|
ktime_t next;
|
|
|
|
if (!tick_nohz_enabled)
|
|
return;
|
|
|
|
local_irq_disable();
|
|
if (tick_switch_to_oneshot(tick_nohz_handler)) {
|
|
local_irq_enable();
|
|
return;
|
|
}
|
|
|
|
ts->nohz_mode = NOHZ_MODE_LOWRES;
|
|
|
|
/*
|
|
* Recycle the hrtimer in ts, so we can share the
|
|
* hrtimer_forward with the highres code.
|
|
*/
|
|
hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
|
|
/* Get the next period */
|
|
next = tick_init_jiffy_update();
|
|
|
|
for (;;) {
|
|
hrtimer_set_expires(&ts->sched_timer, next);
|
|
if (!tick_program_event(next, 0))
|
|
break;
|
|
next = ktime_add(next, tick_period);
|
|
}
|
|
local_irq_enable();
|
|
|
|
printk(KERN_INFO "Switched to NOHz mode on CPU #%d\n",
|
|
smp_processor_id());
|
|
}
|
|
|
|
/*
|
|
* When NOHZ is enabled and the tick is stopped, we need to kick the
|
|
* tick timer from irq_enter() so that the jiffies update is kept
|
|
* alive during long running softirqs. That's ugly as hell, but
|
|
* correctness is key even if we need to fix the offending softirq in
|
|
* the first place.
|
|
*
|
|
* Note, this is different to tick_nohz_restart. We just kick the
|
|
* timer and do not touch the other magic bits which need to be done
|
|
* when idle is left.
|
|
*/
|
|
static void tick_nohz_kick_tick(int cpu, ktime_t now)
|
|
{
|
|
#if 0
|
|
/* Switch back to 2.6.27 behaviour */
|
|
|
|
struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
|
|
ktime_t delta;
|
|
|
|
/*
|
|
* Do not touch the tick device, when the next expiry is either
|
|
* already reached or less/equal than the tick period.
|
|
*/
|
|
delta = ktime_sub(hrtimer_get_expires(&ts->sched_timer), now);
|
|
if (delta.tv64 <= tick_period.tv64)
|
|
return;
|
|
|
|
tick_nohz_restart(ts, now);
|
|
#endif
|
|
}
|
|
|
|
static inline void tick_check_nohz(int cpu)
|
|
{
|
|
struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
|
|
ktime_t now;
|
|
|
|
if (!ts->idle_active && !ts->tick_stopped)
|
|
return;
|
|
now = ktime_get();
|
|
if (ts->idle_active)
|
|
tick_nohz_stop_idle(cpu, now);
|
|
if (ts->tick_stopped) {
|
|
tick_nohz_update_jiffies(now);
|
|
tick_nohz_kick_tick(cpu, now);
|
|
}
|
|
}
|
|
|
|
#else
|
|
|
|
static inline void tick_nohz_switch_to_nohz(void) { }
|
|
static inline void tick_check_nohz(int cpu) { }
|
|
|
|
#endif /* NO_HZ */
|
|
|
|
/*
|
|
* Called from irq_enter to notify about the possible interruption of idle()
|
|
*/
|
|
void tick_check_idle(int cpu)
|
|
{
|
|
tick_check_oneshot_broadcast(cpu);
|
|
tick_check_nohz(cpu);
|
|
}
|
|
|
|
/*
|
|
* High resolution timer specific code
|
|
*/
|
|
#ifdef CONFIG_HIGH_RES_TIMERS
|
|
/*
|
|
* We rearm the timer until we get disabled by the idle code.
|
|
* Called with interrupts disabled and timer->base->cpu_base->lock held.
|
|
*/
|
|
static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer)
|
|
{
|
|
struct tick_sched *ts =
|
|
container_of(timer, struct tick_sched, sched_timer);
|
|
struct pt_regs *regs = get_irq_regs();
|
|
ktime_t now = ktime_get();
|
|
int cpu = smp_processor_id();
|
|
|
|
#ifdef CONFIG_NO_HZ
|
|
/*
|
|
* Check if the do_timer duty was dropped. We don't care about
|
|
* concurrency: This happens only when the cpu in charge went
|
|
* into a long sleep. If two cpus happen to assign themself to
|
|
* this duty, then the jiffies update is still serialized by
|
|
* xtime_lock.
|
|
*/
|
|
if (unlikely(tick_do_timer_cpu == TICK_DO_TIMER_NONE))
|
|
tick_do_timer_cpu = cpu;
|
|
#endif
|
|
|
|
/* Check, if the jiffies need an update */
|
|
if (tick_do_timer_cpu == cpu)
|
|
tick_do_update_jiffies64(now);
|
|
|
|
/*
|
|
* Do not call, when we are not in irq context and have
|
|
* no valid regs pointer
|
|
*/
|
|
if (regs) {
|
|
/*
|
|
* 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(user_mode(regs));
|
|
profile_tick(CPU_PROFILING);
|
|
}
|
|
|
|
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();
|
|
u64 offset;
|
|
|
|
/*
|
|
* Emulate tick processing via per-CPU hrtimers:
|
|
*/
|
|
hrtimer_init(&ts->sched_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
|
|
ts->sched_timer.function = tick_sched_timer;
|
|
|
|
/* Get the next period (per cpu) */
|
|
hrtimer_set_expires(&ts->sched_timer, tick_init_jiffy_update());
|
|
offset = ktime_to_ns(tick_period) >> 1;
|
|
do_div(offset, num_possible_cpus());
|
|
offset *= smp_processor_id();
|
|
hrtimer_add_expires_ns(&ts->sched_timer, offset);
|
|
|
|
for (;;) {
|
|
hrtimer_forward(&ts->sched_timer, now, tick_period);
|
|
hrtimer_start_expires(&ts->sched_timer,
|
|
HRTIMER_MODE_ABS_PINNED);
|
|
/* 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
|
|
}
|
|
#endif /* HIGH_RES_TIMERS */
|
|
|
|
#if defined CONFIG_NO_HZ || defined CONFIG_HIGH_RES_TIMERS
|
|
void tick_cancel_sched_timer(int cpu)
|
|
{
|
|
struct tick_sched *ts = &per_cpu(tick_cpu_sched, cpu);
|
|
|
|
# ifdef CONFIG_HIGH_RES_TIMERS
|
|
if (ts->sched_timer.base)
|
|
hrtimer_cancel(&ts->sched_timer);
|
|
# endif
|
|
|
|
ts->nohz_mode = NOHZ_MODE_INACTIVE;
|
|
}
|
|
#endif
|
|
|
|
/**
|
|
* 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_valid_for_hres() || !tick_is_oneshot_available())
|
|
return 0;
|
|
|
|
if (!allow_nohz)
|
|
return 1;
|
|
|
|
tick_nohz_switch_to_nohz();
|
|
return 0;
|
|
}
|