Messages in this thread | | | Date | Mon, 20 Apr 2020 18:32:32 -0400 | From | Steven Rostedt <> | Subject | Re: [PATCH 2/2] sched: Extract the task putting code from pick_next_task() |
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On Mon, 20 Apr 2020 00:31:52 +0800 Chen Yu <yu.c.chen@intel.com> wrote:
> Introduce a new function finish_prev_task() to do the balance > when necessary, and then put previous task back to the run queue. > This function is extracted from pick_next_task() to prepare for > future usage by other type of task picking logic. > > No functional change. > > Suggested-by: Peter Zijlstra <peterz@infradead.org> > Signed-off-by: Chen Yu <yu.c.chen@intel.com> > --- > kernel/sched/core.c | 39 +++++++++++++++++++++++---------------- > 1 file changed, 23 insertions(+), 16 deletions(-) > > diff --git a/kernel/sched/core.c b/kernel/sched/core.c > index 3a61a3b8eaa9..bf59a5cf030c 100644 > --- a/kernel/sched/core.c > +++ b/kernel/sched/core.c > @@ -3904,6 +3904,28 @@ static inline void schedule_debug(struct task_struct *prev, bool preempt) > schedstat_inc(this_rq()->sched_count); > } > > +static void finish_prev_task(struct rq *rq, struct task_struct *prev, > + struct rq_flags *rf) > +{ > + const struct sched_class *class; > +#ifdef CONFIG_SMP > + /* > + * We must do the balancing pass before put_next_task(), such
I know this is just a cut and paste move, but I'm thinking that this comment is wrong. Shouldn't this be "put_prev_task()" as we have no "put_next_task()" function.
> + * that when we release the rq->lock the task is in the same > + * state as before we took rq->lock. > + * > + * We can terminate the balance pass as soon as we know there is > + * a runnable task of @class priority or higher. > + */ > + for_class_range(class, prev->sched_class, &idle_sched_class) { > + if (class->balance(rq, prev, rf)) > + break; > + } > +#endif > + > + put_prev_task(rq, prev); > +} > + > /* > * Pick up the highest-prio task: > */ > @@ -3937,22 +3959,7 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) > } > > restart: > -#ifdef CONFIG_SMP > - /* > - * We must do the balancing pass before put_next_task(), such > - * that when we release the rq->lock the task is in the same > - * state as before we took rq->lock. > - * > - * We can terminate the balance pass as soon as we know there is > - * a runnable task of @class priority or higher. > - */ > - for_class_range(class, prev->sched_class, &idle_sched_class) { > - if (class->balance(rq, prev, rf)) > - break; > - } > -#endif > - > - put_prev_task(rq, prev); > + finish_prev_task(rq, prev, rf);
I'm not sure I like the name of this function. Perhaps "balance_and_put_prev_task()"? Something more in kind to what the function does.
-- Steve
> > for_each_class(class) { > p = class->pick_next_task(rq);
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