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    Subject[PATCH 06/32] nohz: Move idle ticks stats tracking out of nohz handlers
    Date
    Idle ticks time tracking is merged into nohz stop/restart
    handlers. Pull it out into idle entry/exit handlers instead,
    so that nohz APIs is more idle independant.

    Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: Andrew Morton <akpm@linux-foundation.org>
    Cc: Anton Blanchard <anton@au1.ibm.com>
    Cc: Avi Kivity <avi@redhat.com>
    Cc: Ingo Molnar <mingo@elte.hu>
    Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
    Cc: Paul E . McKenney <paulmck@linux.vnet.ibm.com>
    Cc: Paul Menage <menage@google.com>
    Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
    Cc: Stephen Hemminger <shemminger@vyatta.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Tim Pepper <lnxninja@linux.vnet.ibm.com>
    ---
    kernel/time/tick-sched.c | 34 +++++++++++++++++++---------------
    1 files changed, 19 insertions(+), 15 deletions(-)

    diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
    index 8937d4a..21b187c 100644
    --- a/kernel/time/tick-sched.c
    +++ b/kernel/time/tick-sched.c
    @@ -384,7 +384,6 @@ static void tick_nohz_stop_sched_tick(ktime_t now)

    ts->idle_tick = hrtimer_get_expires(&ts->sched_timer);
    ts->tick_stopped = 1;
    - ts->idle_jiffies = last_jiffies;
    }

    ts->idle_sleeps++;
    @@ -433,8 +432,10 @@ static void __tick_nohz_enter_idle(struct tick_sched *ts, int cpu)
    now = tick_nohz_start_idle(cpu, ts);
    tick_nohz_stop_sched_tick(now);

    - if (!was_stopped && ts->tick_stopped)
    + if (!was_stopped && ts->tick_stopped) {
    + ts->idle_jiffies = ts->last_jiffies;
    rcu_enter_nohz();
    + }
    }

    void tick_nohz_enter_idle(void)
    @@ -498,16 +499,26 @@ static void tick_nohz_restart(struct tick_sched *ts, ktime_t now)
    static void tick_nohz_restart_sched_tick(ktime_t now, struct tick_sched *ts)
    {
    int cpu = smp_processor_id();
    -#ifndef CONFIG_VIRT_CPU_ACCOUNTING
    - unsigned long ticks;
    -#endif

    /* Update jiffies first */
    select_nohz_load_balancer(0);
    tick_do_update_jiffies64(now);
    cpumask_clear_cpu(cpu, nohz_cpu_mask);

    + touch_softlockup_watchdog();
    + /*
    + * Cancel the scheduled timer and restore the tick
    + */
    + ts->tick_stopped = 0;
    + ts->idle_exittime = now;
    +
    + tick_nohz_restart(ts, now);
    +}
    +
    +static void tick_nohz_account_idle_ticks(struct tick_sched *ts)
    +{
    #ifndef CONFIG_VIRT_CPU_ACCOUNTING
    + unsigned long ticks;
    /*
    * We stopped the tick in idle. Update process times would miss the
    * time we slept as update_process_times does only a 1 tick
    @@ -520,15 +531,6 @@ static void tick_nohz_restart_sched_tick(ktime_t now, struct tick_sched *ts)
    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);
    }

    void tick_nohz_exit_idle(void)
    @@ -551,6 +553,7 @@ void tick_nohz_exit_idle(void)
    if (ts->tick_stopped) {
    rcu_exit_nohz();
    tick_nohz_restart_sched_tick(now, ts);
    + tick_nohz_account_idle_ticks(ts);
    }

    local_irq_enable();
    @@ -766,7 +769,8 @@ static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer)
    */
    if (ts->tick_stopped) {
    touch_softlockup_watchdog();
    - ts->idle_jiffies++;
    + if (idle_cpu(cpu))
    + ts->idle_jiffies++;
    }
    update_process_times(user_mode(regs));
    profile_tick(CPU_PROFILING);
    --
    1.7.5.4


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