On Tue, Oct 02, 2018 at 10:23:41PM +0800, Peng Hao wrote:
> find_lock_lowest_rq may or not releease rq lock, but it is fuzzy.
> If not releasing rq lock, it is unnecessary to re-call
> pick_next_oushable_task.
You forgot to mention how much this matters. That is, why did you take
the effort to write this patch.
> Signed-off-by: Peng Hao <peng.h...@zte.com.cn>
> ---
> kernel/sched/rt.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
> index 2e2955a..4d7d322 100644
> --- a/kernel/sched/rt.c
> +++ b/kernel/sched/rt.c
> @@ -1719,6 +1719,7 @@ static struct rq *find_lock_lowest_rq(struct
> task_struct *task, struct rq *rq)
> {
> struct rq *lowest_rq = NULL;
> int tries;
> + bool release_lock = false;
> int cpu;
We generally prefer to keep the variable definitions (reverse) ordered
on line length (reverse-xmas-tree).
>
> for (tries = 0; tries < RT_MAX_TRIES; tries++) {
> @@ -1741,6 +1742,7 @@ static struct rq *find_lock_lowest_rq(struct
> task_struct *task, struct rq *rq)
>
> /* if the prio of this runqueue changed, try again */
> if (double_lock_balance(rq, lowest_rq)) {
> + release_lock = true;
> /*
> * We had to unlock the run queue. In
> * the mean time, task could have
> @@ -1768,6 +1770,8 @@ static struct rq *find_lock_lowest_rq(struct
> task_struct *task, struct rq *rq)
> lowest_rq = NULL;
> }
>
> + if (!lowest_rq && !release_lock)
> + lowest_rq = (void *) -1;
We have a name for that thing, RETRY_TASK. Funnily it means the exact
opposite of what you did. So maybe use that and invert the logic.
> return lowest_rq;
> }
>
You also forgot to do the same to the deadline code; or explain why it
doesn't need it.
