[PATCH 10/39] sched: Factor out update_other_load_avgs() from __update_blocked_others()

Tejun Heo
2024-05-01T15:13:38Z

RT, DL, thermal and irq load and utilization metrics need to be decayed and
updated periodically and before consumption to keep the numbers reasonable.
This is currently done from __update_blocked_others() as a part of the fair
class load balance path. Let's factor it out to update_other_load_avgs().
Pure refactor. No functional changes.

This will be used by the new BPF extensible scheduling class to ensure that
the above metrics are properly maintained.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: David Vernet <dvernet@meta.com>
---
kernel/sched/core.c | 19 +++++++++++++++++++
kernel/sched/fair.c | 16 +++-------------
kernel/sched/sched.h | 3 +++
3 files changed, 25 insertions(+), 13 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 90b505fbb488..7542a39f1fde 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7486,6 +7486,25 @@ int sched_core_idle_cpu(int cpu)
#endif

#ifdef CONFIG_SMP
+/*
+ * Load avg and utiliztion metrics need to be updated periodically and before
+ * consumption. This function updates the metrics for all subsystems except for
+ * the fair class. @rq must be locked and have its clock updated.
+ */
+bool update_other_load_avgs(struct rq *rq)
+{
+ u64 now = rq_clock_pelt(rq);
+ const struct sched_class *curr_class = rq->curr->sched_class;
+ unsigned long thermal_pressure = arch_scale_thermal_pressure(cpu_of(rq));
+
+ lockdep_assert_rq_held(rq);
+
+ return update_rt_rq_load_avg(now, rq, curr_class == &rt_sched_class) |
+ update_dl_rq_load_avg(now, rq, curr_class == &dl_sched_class) |
+ update_thermal_load_avg(rq_clock_thermal(rq), rq, thermal_pressure) |
+ update_irq_load_avg(rq, 0);
+}
+
/*
* This function computes an effective utilization for the given CPU, to be
* used for frequency selection given the linear relation: f = u * f_max.
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 8032256d3972..51301ae13725 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -9283,28 +9283,18 @@ static inline void update_blocked_load_status(struct rq *rq, bool has_blocked) {

static bool __update_blocked_others(struct rq *rq, bool *done)
{
- const struct sched_class *curr_class;
- u64 now = rq_clock_pelt(rq);
- unsigned long thermal_pressure;
- bool decayed;
+ bool updated;

/*
* update_load_avg() can call cpufreq_update_util(). Make sure that RT,
* DL and IRQ signals have been updated before updating CFS.
*/
- curr_class = rq->curr->sched_class;
-
- thermal_pressure = arch_scale_thermal_pressure(cpu_of(rq));
-
- decayed = update_rt_rq_load_avg(now, rq, curr_class == &rt_sched_class) |
- update_dl_rq_load_avg(now, rq, curr_class == &dl_sched_class) |
- update_thermal_load_avg(rq_clock_thermal(rq), rq, thermal_pressure) |
- update_irq_load_avg(rq, 0);
+ updated = update_other_load_avgs(rq);

if (others_have_blocked(rq))
*done = false;

- return decayed;
+ return updated;
}

#ifdef CONFIG_FAIR_GROUP_SCHED
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index bcc8056acadb..ccf2fff0e2ae 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -3042,6 +3042,7 @@ static inline void cpufreq_update_util(struct rq *rq, unsigned int flags) {}
#endif

#ifdef CONFIG_SMP
+bool update_other_load_avgs(struct rq *rq);
unsigned long effective_cpu_util(int cpu, unsigned long util_cfs,
unsigned long *min,
unsigned long *max);
@@ -3084,6 +3085,8 @@ static inline unsigned long cpu_util_rt(struct rq *rq)
{
return READ_ONCE(rq->avg_rt.util_avg);
}
+#else
+static inline bool update_other_load_avgs(struct rq *rq) { return false; }
#endif

#ifdef CONFIG_UCLAMP_TASK
--
2.44.0