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    SubjectRe: [PATCH 03/10] sched: Clean-up struct sd_lb_stat
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    On Tue, Aug 20, 2013 at 12:01 AM, Peter Zijlstra <peterz@infradead.org> wrote:
    > From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
    >
    > There is no reason to maintain separate variables for this_group
    > and busiest_group in sd_lb_stat, except saving some space.
    > But this structure is always allocated in stack, so this saving
    > isn't really benificial [peterz: reducing stack space is good; in this
    > case readability increases enough that I think its still beneficial]
    >
    > This patch unify these variables, so IMO, readability may be improved.
    >
    > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
    > [peterz: lots of style edits, a few fixes and a rename]
    > Signed-off-by: Peter Zijlstra <peterz@infradead.org>
    > Link: http://lkml.kernel.org/r/1375778203-31343-4-git-send-email-iamjoonsoo.kim@lge.com
    > ---
    > kernel/sched/fair.c | 225 +++++++++++++++++++++++++---------------------------
    > 1 file changed, 112 insertions(+), 113 deletions(-)
    >
    > --- a/kernel/sched/fair.c
    > +++ b/kernel/sched/fair.c
    > @@ -4277,36 +4277,6 @@ static unsigned long task_h_load(struct
    >
    [snip]...
    > - env->imbalance = DIV_ROUND_CLOSEST(
    > - sds->max_load * sds->busiest->sgp->power, SCHED_POWER_SCALE);
    > + env->imbalance = DIV_ROUND_CLOSEST(sds->busiest_stat.avg_load *
    > + sds->busiest->sgp->power, SCHED_POWER_SCALE);
    >

    I am wondering whether we could change this line as below is more appropriate,
    since it would avoid the division here:
    env->imbalance = (sds->busiest_stat.avg_load * sds->busiest->sgp->power)
    >> SCHED_POWER_SHIFT;

    I am not sure whether compiler would be smarter enough to covert into
    >> operation,
    if it see SCHED_POWER_SCALE is 1024 here.

    Thanks,
    Lei


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