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Message-Id: <20240813224015.724111109@infradead.org>
Date: Wed, 14 Aug 2024 00:25:50 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: mingo@...nel.org,
tj@...nel.org,
void@...ifault.com
Cc: peterz@...radead.org,
juri.lelli@...hat.com,
vincent.guittot@...aro.org,
dietmar.eggemann@....com,
rostedt@...dmis.org,
bsegall@...gle.com,
mgorman@...e.de,
vschneid@...hat.com,
linux-kernel@...r.kernel.org,
joelaf@...gle.com
Subject: [PATCH 2/9] sched: Fixup set_next_task() implementations
The rule is that:
pick_next_task() := pick_task() + set_next_task(.first = true)
Turns out, there's still a few things in pick_next_task() that are
missing from that combination.
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
kernel/sched/deadline.c | 6 ++--
kernel/sched/fair.c | 62 ++++++++++++++++++++++++------------------------
2 files changed, 34 insertions(+), 34 deletions(-)
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -2392,6 +2392,9 @@ static void set_next_task_dl(struct rq *
update_dl_rq_load_avg(rq_clock_pelt(rq), rq, 0);
deadline_queue_push_tasks(rq);
+
+ if (hrtick_enabled(rq))
+ start_hrtick_dl(rq, &p->dl);
}
static struct sched_dl_entity *pick_next_dl_entity(struct dl_rq *dl_rq)
@@ -2458,9 +2461,6 @@ static struct task_struct *pick_next_tas
if (!p->dl_server)
set_next_task_dl(rq, p, true);
- if (hrtick_enabled(rq))
- start_hrtick_dl(rq, &p->dl);
-
return p;
}
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -8758,6 +8758,9 @@ static struct task_struct *pick_task_fai
return task_of(se);
}
+static void __set_next_task_fair(struct rq *rq, struct task_struct *p, bool first);
+static void set_next_task_fair(struct rq *rq, struct task_struct *p, bool first);
+
struct task_struct *
pick_next_task_fair(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
{
@@ -8806,33 +8809,17 @@ pick_next_task_fair(struct rq *rq, struc
put_prev_entity(cfs_rq, pse);
set_next_entity(cfs_rq, se);
+
+ __set_next_task_fair(rq, p, true);
}
- goto done;
+ return p;
+
simple:
#endif
if (prev)
put_prev_task(rq, prev);
-
- for_each_sched_entity(se)
- set_next_entity(cfs_rq_of(se), se);
-
-done: __maybe_unused;
-#ifdef CONFIG_SMP
- /*
- * Move the next running task to the front of
- * the list, so our cfs_tasks list becomes MRU
- * one.
- */
- list_move(&p->se.group_node, &rq->cfs_tasks);
-#endif
-
- if (hrtick_enabled_fair(rq))
- hrtick_start_fair(rq, p);
-
- update_misfit_status(p, rq);
- sched_fair_update_stop_tick(rq, p);
-
+ set_next_task_fair(rq, p, true);
return p;
idle:
@@ -13142,12 +13129,7 @@ static void switched_to_fair(struct rq *
}
}
-/* Account for a task changing its policy or group.
- *
- * This routine is mostly called to set cfs_rq->curr field when a task
- * migrates between groups/classes.
- */
-static void set_next_task_fair(struct rq *rq, struct task_struct *p, bool first)
+static void __set_next_task_fair(struct rq *rq, struct task_struct *p, bool first)
{
struct sched_entity *se = &p->se;
@@ -13160,6 +13142,27 @@ static void set_next_task_fair(struct rq
list_move(&se->group_node, &rq->cfs_tasks);
}
#endif
+ if (!first)
+ return;
+
+ SCHED_WARN_ON(se->sched_delayed);
+
+ if (hrtick_enabled_fair(rq))
+ hrtick_start_fair(rq, p);
+
+ update_misfit_status(p, rq);
+ sched_fair_update_stop_tick(rq, p);
+}
+
+/*
+ * Account for a task changing its policy or group.
+ *
+ * This routine is mostly called to set cfs_rq->curr field when a task
+ * migrates between groups/classes.
+ */
+static void set_next_task_fair(struct rq *rq, struct task_struct *p, bool first)
+{
+ struct sched_entity *se = &p->se;
for_each_sched_entity(se) {
struct cfs_rq *cfs_rq = cfs_rq_of(se);
@@ -13169,10 +13172,7 @@ static void set_next_task_fair(struct rq
account_cfs_rq_runtime(cfs_rq, 0);
}
- if (!first)
- return;
-
- SCHED_WARN_ON(se->sched_delayed);
+ __set_next_task_fair(rq, p, first);
}
void init_cfs_rq(struct cfs_rq *cfs_rq)
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