On Tue, Aug 20, 2013 at 12:01 AM, Peter Zijlstra <pet...@infradead.org> wrote:
> From: Joonsoo Kim <iamjoonsoo....@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....@lge.com>
> [peterz: lots of style edits, a few fixes and a rename]
> Signed-off-by: Peter Zijlstra <pet...@infradead.org>
> Link:
> http://lkml.kernel.org/r/1375778203-31343-4-git-send-email-iamjoonsoo....@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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