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    Subject[RFC PATCH 2 2/2] sched: Nominate a power-efficient ilb in select_nohz_balancer()
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    The CPU that first goes idle becomes the idle-load-balancer and remains
    that until either it picks up a task or till all the CPUs of the system
    goes idle.

    Optimize this further to allow it to relinquish it's post
    once all it's siblings in the power-aware sched_domain go idle, thereby
    allowing the whole package-core to go idle. While relinquising the post,
    nominate another an idle-load balancer from a semi-idle core/package.

    Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
    ---

    kernel/sched.c | 18 +++++++++++++++++-
    1 files changed, 17 insertions(+), 1 deletions(-)

    diff --git a/kernel/sched.c b/kernel/sched.c
    index d702be7..bbf367d 100644
    --- a/kernel/sched.c
    +++ b/kernel/sched.c
    @@ -4402,8 +4402,24 @@ int select_nohz_load_balancer(int stop_tick)
    /* make me the ilb owner */
    if (atomic_cmpxchg(&nohz.load_balancer, -1, cpu) == -1)
    return 1;
    - } else if (atomic_read(&nohz.load_balancer) == cpu)
    + } else if (atomic_read(&nohz.load_balancer) == cpu) {
    + int new_ilb;
    +
    + if (!(sched_smt_power_savings ||
    + sched_mc_power_savings))
    + return 1;
    + /*
    + * Check to see if there is a more power-efficient
    + * ilb.
    + */
    + new_ilb = find_new_ilb(cpu);
    + if (new_ilb < nr_cpu_ids && new_ilb != cpu) {
    + atomic_set(&nohz.load_balancer, -1);
    + resched_cpu(new_ilb);
    + return 0;
    + }
    return 1;
    + }
    } else {
    if (!cpumask_test_cpu(cpu, nohz.cpu_mask))
    return 0;


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