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    SubjectRe: [tip:sched/core] sched/fair: Correct unit of load_above_capacity
    On Thu, May 12, 2016 at 03:31:51AM -0700, tip-bot for Morten Rasmussen wrote:
    > Commit-ID: cfa10334318d8212d007da8c771187643c9cef35
    > Gitweb: http://git.kernel.org/tip/cfa10334318d8212d007da8c771187643c9cef35
    > Author: Morten Rasmussen <morten.rasmussen@arm.com>
    > AuthorDate: Fri, 29 Apr 2016 20:32:40 +0100
    > Committer: Ingo Molnar <mingo@kernel.org>
    > CommitDate: Thu, 12 May 2016 09:55:33 +0200
    >
    > sched/fair: Correct unit of load_above_capacity
    >
    > In calculate_imbalance() load_above_capacity currently has the unit
    > [capacity] while it is used as being [load/capacity]. Not only is it
    > wrong it also makes it unlikely that load_above_capacity is ever used
    > as the subsequent code picks the smaller of load_above_capacity and
    > the avg_load
    >
    > This patch ensures that load_above_capacity has the right unit
    > [load/capacity].
    >
    > Signed-off-by: Morten Rasmussen <morten.rasmussen@arm.com>
    > [ Changed changelog to note it was in capacity unit; +rebase. ]
    > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
    > Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
    > Cc: Linus Torvalds <torvalds@linux-foundation.org>
    > Cc: Mike Galbraith <efault@gmx.de>
    > Cc: Peter Zijlstra <peterz@infradead.org>
    > Cc: Thomas Gleixner <tglx@linutronix.de>
    > Cc: linux-kernel@vger.kernel.org
    > Link: http://lkml.kernel.org/r/1461958364-675-4-git-send-email-dietmar.eggemann@arm.com
    > Signed-off-by: Ingo Molnar <mingo@kernel.org>
    > ---
    > kernel/sched/fair.c | 6 ++++--
    > 1 file changed, 4 insertions(+), 2 deletions(-)
    >
    > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
    > index 2338105..218f8e8 100644
    > --- a/kernel/sched/fair.c
    > +++ b/kernel/sched/fair.c
    > @@ -7067,9 +7067,11 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s
    > if (busiest->group_type == group_overloaded &&
    > local->group_type == group_overloaded) {
    > load_above_capacity = busiest->sum_nr_running * SCHED_CAPACITY_SCALE;
    > - if (load_above_capacity > busiest->group_capacity)
    > + if (load_above_capacity > busiest->group_capacity) {
    > load_above_capacity -= busiest->group_capacity;
    > - else
    > + load_above_capacity *= NICE_0_LOAD;
    > + load_above_capacity /= busiest->group_capacity;
    > + } else
    > load_above_capacity = ~0UL;
    > }

    Hi Morten,

    I got the feeling this might be wrong, the NICE_0_LOAD should be scaled down.
    But I hope I am wrong.

    Vincent, could you take a look?

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