sched clock: couple local and remote clocks

u64 sched_clock_cpu(int cpu)

{

	struct sched_clock_data *scd = cpu_sdc(cpu);

	u64 now, clock;

	u64 now, clock, this_clock, remote_clock;

	if (unlikely(!sched_clock_running))

		return 0ull;

	now = sched_clock();

	if (cpu != raw_smp_processor_id()) {

		/*

		 * in order to update a remote cpu's clock based on our

		 * unstable raw time rebase it against:

		 *   tick_raw		(offset between raw counters)

		 *   tick_gotd          (tick offset between cpus)

		 */

		struct sched_clock_data *my_scd = this_scd();

		lock_double_clock(scd, my_scd);

		now += scd->tick_raw - my_scd->tick_raw;

		now += my_scd->tick_gtod - scd->tick_gtod;

		this_clock = __update_sched_clock(my_scd, now);

		remote_clock = scd->clock;

		__raw_spin_unlock(&my_scd->lock);

		/*

		 * Use the opportunity that we have both locks

		 * taken to couple the two clocks: we take the

		 * larger time as the latest time for both

		 * runqueues. (this creates monotonic movement)

		 */

		if (likely(remote_clock < this_clock)) {

			clock = this_clock;

			scd->clock = clock;

		} else {

		__raw_spin_lock(&scd->lock);

			/*

			 * Should be rare, but possible:

			 */

			clock = remote_clock;

			my_scd->clock = remote_clock;

		}

		__raw_spin_unlock(&my_scd->lock);

	} else {

		__raw_spin_lock(&scd->lock);

		clock = __update_sched_clock(scd, now);

	}

	__raw_spin_unlock(&scd->lock);

void sched_clock_idle_wakeup_event(u64 delta_ns)

{

	struct sched_clock_data *scd = this_scd();

	u64 now = sched_clock();

	/*

	 * Override the previous timestamp and ignore all