Re: [PATCH 2/2] sched/core: Uncookied force idle accounting per cpu

[Josh Don]

On Thu, Jan 6, 2022 at 4:05 AM cruzzhao <cruzzhao@xxxxxxxxxxxxxxxxx> wrote:
>
>
> 在 2022/1/6 上午4:59, Josh Don 写道:
>
> It's a good idea to combine them into a single sum. I separated them in
> order to be consistent with the task accounting and for easy to understand.
> As for change the task accounting, I've tried but I haven't found a
> proper method to do so. I've considered the following methods:
> 1. Account the uncookie'd force idle time to the uncookie'd task, but
> it'll be hard to trace the uncookie'd task.

Not sure what you mean there, I think you just need to add

--- a/kernel/sched/core_sched.c
+++ b/kernel/sched/core_sched.c
@@ -294,7 +294,7 @@ void sched_core_account_forceidle(struct rq *rq)
                rq_i = cpu_rq(i);
                p = rq_i->core_pick ?: rq_i->curr;

-               if (!p->core_cookie)
+               if (p == rq_i->idle)
                        continue;

                __schedstat_add(p->stats.core_forceidle_sum, delta)

> 2. Account the uncookie'd force idle time to the cookie'd task in the
> core_tree of the core, but it will cost a lot on traversing the core_tree.
>
> Many thanks for suggestions.
> Best,
> Cruz Zhao
>
> > Why do you need this separated out into two fields then? Could we just
> > combine the uncookie'd and cookie'd forced idle into a single sum?
> >
> > IMO it is fine to account the forced idle from uncookie'd tasks, but
> > we should then also change the task accounting to do the same, for
> > consistency.