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    Subject[patch V3 21/22] timer: Split out index calculation
    From: Anna-Maria Gleixner <anna-maria@linutronix.de>

    For further optimizations we need to seperate index calculation and
    queueing. No functional change.

    Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
    Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: Chris Mason <clm@fb.com>
    Cc: Eric Dumazet <edumazet@google.com>
    Cc: rt@linutronix.de
    Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
    Cc: Arjan van de Ven <arjan@infradead.org>

    ---
    kernel/time/timer.c | 45 +++++++++++++++++++++++++++++++--------------
    1 file changed, 31 insertions(+), 14 deletions(-)

    --- a/kernel/time/timer.c
    +++ b/kernel/time/timer.c
    @@ -471,12 +471,9 @@ static inline unsigned calc_index(unsign
    return LVL_OFFS(lvl) + (expires & LVL_MASK);
    }

    -static void
    -__internal_add_timer(struct timer_base *base, struct timer_list *timer)
    +static int calc_wheel_index(unsigned long expires, unsigned long clk)
    {
    - unsigned long expires = timer->expires;
    - unsigned long delta = expires - base->clk;
    - struct hlist_head *vec;
    + unsigned long delta = expires - clk;
    unsigned int idx;

    if (delta < LVL_START(1)) {
    @@ -496,7 +493,7 @@ static void
    } else if (LVL_DEPTH > 8 && delta < LVL_START(8)) {
    idx = calc_index(expires, 7);
    } else if ((long) delta < 0) {
    - idx = base->clk & LVL_MASK;
    + idx = clk & LVL_MASK;
    } else {
    /*
    * Force expire obscene large timeouts to expire at the
    @@ -507,20 +504,33 @@ static void

    idx = calc_index(expires, LVL_DEPTH - 1);
    }
    - /*
    - * Enqueue the timer into the array bucket, mark it pending in
    - * the bitmap and store the index in the timer flags.
    - */
    - vec = base->vectors + idx;
    - hlist_add_head(&timer->entry, vec);
    + return idx;
    +}
    +
    +/*
    + * Enqueue the timer into the hash bucket, mark it pending in
    + * the bitmap and store the index in the timer flags.
    + */
    +static void enqueue_timer(struct timer_base *base, struct timer_list *timer,
    + unsigned int idx)
    +{
    + hlist_add_head(&timer->entry, base->vectors + idx);
    __set_bit(idx, base->pending_map);
    timer_set_idx(timer, idx);
    }

    -static void internal_add_timer(struct timer_base *base, struct timer_list *timer)
    +static void
    +__internal_add_timer(struct timer_base *base, struct timer_list *timer)
    {
    - __internal_add_timer(base, timer);
    + unsigned int idx;
    +
    + idx = calc_wheel_index(timer->expires, base->clk);
    + enqueue_timer(base, timer, idx);
    +}

    +static void
    +trigger_dyntick_cpu(struct timer_base *base, struct timer_list *timer)
    +{
    /*
    * We might have to IPI the remote CPU if the base is idle and the
    * timer is not deferrable. If the other cpu is on the way to idle
    @@ -545,6 +555,13 @@ static void internal_add_timer(struct ti
    wake_up_nohz_cpu(base->cpu);
    }

    +static void
    +internal_add_timer(struct timer_base *base, struct timer_list *timer)
    +{
    + __internal_add_timer(base, timer);
    + trigger_dyntick_cpu(base, timer);
    +}
    +
    #ifdef CONFIG_TIMER_STATS
    void __timer_stats_timer_set_start_info(struct timer_list *timer, void *addr)
    {

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