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Subject[PATCH] sched/fair: Clean up update_blocked_averages()
Date
First of all, with CONFIG_NO_HZ_COMMON is disabled, we don't need to call
cfs_rq_has_blocked() and others_have_blocked(). And the local variable
'done' is unnecessary as well.

So we put the functions in the #ifdef block so that compiler can help us
optimize the code(e.g. the local variable 'done' and the function call).

After do that, we introduce a function named update_rq_blocked_load() to
remove #ifdef from update_blocked_averages(), which can make the code
clean.

Second, there are some the same function call in update_blocked_averages()
regardless of whether CONFIG_FAIR_GROUP_SCHED is enabled or not. That is
rt, dl and irq's load_avg update. So let the update_others_load_avg() do
it.

Signed-off-by: Muchun Song <smuchun@gmail.com>
---
kernel/sched/fair.c | 59 +++++++++++++++++++++++++++++----------------
1 file changed, 38 insertions(+), 21 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index e30dea59d215..89b3b4a18eee 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7367,6 +7367,7 @@ static void attach_tasks(struct lb_env *env)
rq_unlock(env->dst_rq, &rf);
}

+#ifdef CONFIG_NO_HZ_COMMON
static inline bool cfs_rq_has_blocked(struct cfs_rq *cfs_rq)
{
if (cfs_rq->avg.load_avg)
@@ -7394,6 +7395,37 @@ static inline bool others_have_blocked(struct rq *rq)
return false;
}

+static inline void update_rq_blocked_load(struct rq *rq, bool clear)
+{
+ rq->last_blocked_load_update_tick = jiffies;
+ if (clear)
+ rq->has_blocked_load = 0;
+}
+#else /* !CONFIG_NO_HZ_COMMON */
+static inline bool cfs_rq_has_blocked(struct cfs_rq *cfs_rq)
+{
+ return false;
+}
+
+static inline bool others_have_blocked(struct rq *rq)
+{
+ return false;
+}
+
+static inline void update_rq_blocked_load(struct rq *rq, bool clear)
+{
+}
+#endif /* CONFIG_NO_HZ_COMMON */
+
+static void update_others_load_avg(struct rq *rq)
+{
+ const struct sched_class *curr = rq->curr->sched_class;
+
+ update_rt_rq_load_avg(rq_clock_task(rq), rq, curr == &rt_sched_class);
+ update_dl_rq_load_avg(rq_clock_task(rq), rq, curr == &dl_sched_class);
+ update_irq_load_avg(rq, 0);
+}
+
#ifdef CONFIG_FAIR_GROUP_SCHED

static inline bool cfs_rq_is_decayed(struct cfs_rq *cfs_rq)
@@ -7417,7 +7449,6 @@ static void update_blocked_averages(int cpu)
{
struct rq *rq = cpu_rq(cpu);
struct cfs_rq *cfs_rq, *pos;
- const struct sched_class *curr_class;
struct rq_flags rf;
bool done = true;

@@ -7455,19 +7486,12 @@ static void update_blocked_averages(int cpu)
done = false;
}

- curr_class = rq->curr->sched_class;
- update_rt_rq_load_avg(rq_clock_task(rq), rq, curr_class == &rt_sched_class);
- update_dl_rq_load_avg(rq_clock_task(rq), rq, curr_class == &dl_sched_class);
- update_irq_load_avg(rq, 0);
+ update_others_load_avg(rq);
/* Don't need periodic decay once load/util_avg are null */
- if (others_have_blocked(rq))
+ if (done && others_have_blocked(rq))
done = false;

-#ifdef CONFIG_NO_HZ_COMMON
- rq->last_blocked_load_update_tick = jiffies;
- if (done)
- rq->has_blocked_load = 0;
-#endif
+ update_rq_blocked_load(rq, done);
rq_unlock_irqrestore(rq, &rf);
}

@@ -7522,22 +7546,15 @@ static inline void update_blocked_averages(int cpu)
{
struct rq *rq = cpu_rq(cpu);
struct cfs_rq *cfs_rq = &rq->cfs;
- const struct sched_class *curr_class;
struct rq_flags rf;

rq_lock_irqsave(rq, &rf);
update_rq_clock(rq);
update_cfs_rq_load_avg(cfs_rq_clock_task(cfs_rq), cfs_rq);

- curr_class = rq->curr->sched_class;
- update_rt_rq_load_avg(rq_clock_task(rq), rq, curr_class == &rt_sched_class);
- update_dl_rq_load_avg(rq_clock_task(rq), rq, curr_class == &dl_sched_class);
- update_irq_load_avg(rq, 0);
-#ifdef CONFIG_NO_HZ_COMMON
- rq->last_blocked_load_update_tick = jiffies;
- if (!cfs_rq_has_blocked(cfs_rq) && !others_have_blocked(rq))
- rq->has_blocked_load = 0;
-#endif
+ update_others_load_avg(rq);
+ update_rq_blocked_load(rq, !cfs_rq_has_blocked(cfs_rq) &&
+ !others_have_blocked(rq));
rq_unlock_irqrestore(rq, &rf);
}

--
2.17.1
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