Re: [PATCH 2/2] sched: add statistic for rq->max_idle_balance_cost

[Peter Zijlstra <peterz@infradead.org>]

On Thu, Jan 23, 2014 at 02:49:25PM +0800, Alex Shi wrote:
> On 01/23/2014 02:10 AM, Jason Low wrote:
> >>> > >  	P64(avg_idle);
> >>> > > +	P64(max_idle_balance_cost);
> >>> > >  #endif
> >>> > >   	P(ttwu_count);
> >> > 
> >> > Not also the per-sd value in sd_alloc_ctl_domain_table() ?
> > Yeah, tracking the sd->max_newidle_lb_cost can also be useful.
> > 
> > 
> 
> Thanks for suggestion!
> 
> I thought the sd->max_newidle_lb_cost keep changing. But yes, it's
> still meaningful. 
> BTW, in the pandaboard ES, sd balance cost is about 1~2ms.

That's an insane amount of time for only 2 cpus.

> ---
> 
> From d37e712b623fb6776d0caba8e4bd06460e26b84e Mon Sep 17 00:00:00 2001
> From: Alex Shi <alex.shi@linaro.org>
> Date: Tue, 21 Jan 2014 13:28:55 +0800
> Subject: [PATCH] sched: add statistic for newidle load balance cost
> 
> Tracking rq->max_idle_balance_cost and sd->max_newidle_lb_cost
> It's useful to track these values in debug mode.
> 
> Signed-off-by: Alex Shi <alex.shi@linaro.org>
> ---
>  kernel/sched/core.c  | 7 +++++--
>  kernel/sched/debug.c | 1 +
>  2 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index c3f3824..a046bc3 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -4293,7 +4293,7 @@ set_table_entry(struct ctl_table *entry,
>  static struct ctl_table *
>  sd_alloc_ctl_domain_table(struct sched_domain *sd)
>  {
> -	struct ctl_table *table = sd_alloc_ctl_entry(8);
> +	struct ctl_table *table = sd_alloc_ctl_entry(9);

tip/master has 13 there, not 8.