Hi Jason,
On 04/24/2014 07:00 AM, Jason Low wrote:
> Commit e5fc6611 can potentially cause rq->max_idle_balance_cost to not be
> updated, even when load_balance(NEWLY_IDLE) is attempted and the per-sd
> max cost value is updated.
>
> In this patch, we update the rq->max_idle_balance_cost regardless of
> whether or not a task has been enqueued while browsing the domains.
>
> Signed-off-by: Jason Low <jason.l...@hp.com>
> ---
> kernel/sched/fair.c | 9 +++++----
> 1 files changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 43232b8..3e3ffb8 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c
> @@ -6658,6 +6658,7 @@ static int idle_balance(struct rq *this_rq)
> int this_cpu = this_rq->cpu;
>
> idle_enter_fair(this_rq);
> +
> /*
> * We must set idle_stamp _before_ calling idle_balance(), such that we
> * measure the duration of idle_balance() as idle time.
> @@ -6710,9 +6711,12 @@ static int idle_balance(struct rq *this_rq)
>
> raw_spin_lock(&this_rq->lock);
>
> + if (curr_cost > this_rq->max_idle_balance_cost)
> + this_rq->max_idle_balance_cost = curr_cost;
> +
> /*
What about the update of next_balance field? See the code snippet below.
This will also be skipped as a consequence of the commit e5fc6611 right?
if (pulled_task || time_after(jiffies, this_rq->next_balance)) {
/*
* We are going idle. next_balance may be set based on
* a busy processor. So reset next_balance.
*/
this_rq->next_balance = next_balance;
}
Also the comment in the above snippet does not look right to me.
It says "we are going idle" but the condition checks for pulled_task.
Regards
Preeti U Murthy
> * While browsing the domains, we released the rq lock.
> - * A task could have be enqueued in the meantime
> + * A task could have been enqueued in the meantime.
> */
> if (this_rq->cfs.h_nr_running && !pulled_task) {
> pulled_task = 1;
> @@ -6727,9 +6731,6 @@ static int idle_balance(struct rq *this_rq)
> this_rq->next_balance = next_balance;
> }
>
> - if (curr_cost > this_rq->max_idle_balance_cost)
> - this_rq->max_idle_balance_cost = curr_cost;
> -
> out:
> /* Is there a task of a high priority class? */
> if (this_rq->nr_running != this_rq->cfs.h_nr_running)
>
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
