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    SubjectRe: [patch 1/2] sched, timers: move calc_load() to scheduler
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    On Thu, 2009-05-14 at 11:21 +0000, Thomas Gleixner wrote:
    > plain text document attachment (move-calc-load-to-scheduler-v1.patch)

    > +/*
    > + * calc_load - update the avenrun load estimates 10 ticks after the
    > + * CPUs have updated calc_load_tasks.
    > + */
    > +void calc_global_load(void)
    > +{
    > + unsigned long upd = calc_load_update + 10;
    > + long active;
    > +
    > + if (time_before(jiffies, upd))
    > + return;
    >
    > + active = atomic_long_read(&calc_load_tasks);
    > + active = active > 0 ? active * FIXED_1 : 0;
    >
    > + avenrun[0] = calc_load(avenrun[0], EXP_1, active);
    > + avenrun[1] = calc_load(avenrun[1], EXP_5, active);
    > + avenrun[2] = calc_load(avenrun[2], EXP_15, active);
    > +
    > + calc_load_update += LOAD_FREQ;
    > +}

    > @@ -1211,7 +1160,8 @@ static inline void update_times(unsigned
    > void do_timer(unsigned long ticks)
    > {
    > jiffies_64 += ticks;
    > - update_times(ticks);
    > + update_wall_time();
    > + calc_global_load();
    > }

    I can see multiple cpus fall into calc_global_load() concurrently, which
    would 'age' the load faster than expected.

    Should we plug that hole?



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