Re: [PATCH v3 04/14] sched/core: uclamp: update CPU's refcount on clamp changes
From: Patrick Bellasi <hidden>
Date: 2018-08-16 13:23:00
Also in:
lkml
Subsystem:
scheduler, the rest · Maintainers:
Ingo Molnar, Peter Zijlstra, Juri Lelli, Vincent Guittot, Linus Torvalds
On 15-Aug 17:02, Dietmar Eggemann wrote:
On 08/06/2018 06:39 PM, Patrick Bellasi wrote: [...]quoted
+/** + * uclamp_task_active: check if a task is currently clamping a CPU + * @p: the task to check + * + * A task actively affects the utilization clamp of a CPU if: + * - it's currently enqueued or running on that CPU + * - it's refcounted in at least one clamp group of that CPU + * + * Return: true if p is currently clamping the utilization of its CPU. + */ +static inline bool uclamp_task_active(struct task_struct *p) +{ + struct rq *rq = task_rq(p); + int clamp_id; + + lockdep_assert_held(&p->pi_lock); + lockdep_assert_held(&rq->lock); + + if (!task_on_rq_queued(p) && !p->on_cpu) + return false; + + for (clamp_id = 0; clamp_id < UCLAMP_CNT; ++clamp_id) { + if (uclamp_task_affects(p, clamp_id)) + return true; + } + + return false; +}Looks like that uclamp_task_active() is only used once (in uclamp_task_update_active()). Can you not code the if condition and the for loop directly in uclamp_task_update_active()? This would save code (lockdep_assert_held() etc.) and comment lines.
Yes, that's possible... and we will have: ---8<---
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index ae528a7b9bef..0c8bec892018 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c@@ -1331,7 +1331,9 @@ uclamp_task_update_active(struct task_struct *p, int clamp_id, int group_id) * index, then that task is not yet RUNNABLE and it's going to be * enqueued with the proper clamp group value. */ - if (!uclamp_task_active(p)) + if (!task_on_rq_queued(p) && !p->on_cpu) + goto done; + if (!uclamp_task_affects(p, clamp_id)) goto done; /* Release p's currently referenced clamp group */
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 11d139faed1f..65fdf4abc6ff 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h@@ -2231,35 +2231,6 @@ static inline bool uclamp_task_affects(struct task_struct *p, int clamp_id) { return (p->uclamp[clamp_id].effective.group_id != UCLAMP_NOT_VALID); } - -/** - * uclamp_task_active: check if a task is currently clamping a CPU - * @p: the task to check - * - * A task actively affects the utilization clamp of a CPU if: - * - it's currently enqueued or running on that CPU - * - it's refcounted in at least one clamp group of that CPU - * - * Return: true if p is currently clamping the utilization of its CPU. - */ -static inline bool uclamp_task_active(struct task_struct *p) -{ - struct rq *rq = task_rq(p); - int clamp_id; - - lockdep_assert_held(&p->pi_lock); - lockdep_assert_held(&rq->lock); - - if (!task_on_rq_queued(p) && !p->on_cpu) - return false; - - for (clamp_id = 0; clamp_id < UCLAMP_CNT; ++clamp_id) { - if (uclamp_task_affects(p, clamp_id)) - return true; - } - - return false; -} #endif /* CONFIG_UCLAMP_TASK */ #ifdef CONFIG_CPU_FREQ ---8<---
I'll add this to the next posting! Cheers Patrick -- #include <best/regards.h> Patrick Bellasi