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Message-Id: <20220709151353.32883-4-zhouchengming@bytedance.com>
Date: Sat, 9 Jul 2022 23:13:48 +0800
From: Chengming Zhou <zhouchengming@...edance.com>
To: mingo@...hat.com, peterz@...radead.org, vincent.guittot@...aro.org,
dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com,
vschneid@...hat.com
Cc: linux-kernel@...r.kernel.org,
Chengming Zhou <zhouchengming@...edance.com>
Subject: [PATCH 3/8] sched/fair: remove redundant cpu_cgrp_subsys->fork()
We use cpu_cgrp_subsys->fork() to set task group for the new fair task
in cgroup_post_fork().
Since commit b1e8206582f9 ("sched: Fix yet more sched_fork() races")
has already set task group for the new fair task in sched_cgroup_fork(),
so cpu_cgrp_subsys->fork() can be removed.
cgroup_can_fork() --> pin parent's sched_task_group
sched_cgroup_fork()
__set_task_cpu --> set task group
cgroup_post_fork()
ss->fork() := cpu_cgroup_fork() --> set again
After this patch's change, task_change_group_fair() only need to
care about task cgroup migration, make the code much simplier.
This patch also move the task se depth setting to set_task_rq(), which
will set correct depth for the new task se in sched_cgroup_fork().
The se depth setting in attach_entity_cfs_rq() is removed since
set_task_rq() is a better place to do this when task moves across
CPUs/groups.
Signed-off-by: Chengming Zhou <zhouchengming@...edance.com>
Reviewed-by: Vincent Guittot <vincent.guittot@...aro.org>
---
kernel/sched/core.c | 27 ++++-----------------------
kernel/sched/fair.c | 31 +------------------------------
kernel/sched/sched.h | 6 ++----
3 files changed, 7 insertions(+), 57 deletions(-)
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index c215b5adc707..d85fdea51e3a 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -481,8 +481,7 @@ sched_core_dequeue(struct rq *rq, struct task_struct *p, int flags) { }
* p->se.load, p->rt_priority,
* p->dl.dl_{runtime, deadline, period, flags, bw, density}
* - sched_setnuma(): p->numa_preferred_nid
- * - sched_move_task()/
- * cpu_cgroup_fork(): p->sched_task_group
+ * - sched_move_task(): p->sched_task_group
* - uclamp_update_active() p->uclamp*
*
* p->state <- TASK_*:
@@ -10127,7 +10126,7 @@ void sched_release_group(struct task_group *tg)
spin_unlock_irqrestore(&task_group_lock, flags);
}
-static void sched_change_group(struct task_struct *tsk, int type)
+static void sched_change_group(struct task_struct *tsk)
{
struct task_group *tg;
@@ -10143,7 +10142,7 @@ static void sched_change_group(struct task_struct *tsk, int type)
#ifdef CONFIG_FAIR_GROUP_SCHED
if (tsk->sched_class->task_change_group)
- tsk->sched_class->task_change_group(tsk, type);
+ tsk->sched_class->task_change_group(tsk);
else
#endif
set_task_rq(tsk, task_cpu(tsk));
@@ -10174,7 +10173,7 @@ void sched_move_task(struct task_struct *tsk)
if (running)
put_prev_task(rq, tsk);
- sched_change_group(tsk, TASK_MOVE_GROUP);
+ sched_change_group(tsk);
if (queued)
enqueue_task(rq, tsk, queue_flags);
@@ -10252,23 +10251,6 @@ static void cpu_cgroup_css_free(struct cgroup_subsys_state *css)
sched_unregister_group(tg);
}
-/*
- * This is called before wake_up_new_task(), therefore we really only
- * have to set its group bits, all the other stuff does not apply.
- */
-static void cpu_cgroup_fork(struct task_struct *task)
-{
- struct rq_flags rf;
- struct rq *rq;
-
- rq = task_rq_lock(task, &rf);
-
- update_rq_clock(rq);
- sched_change_group(task, TASK_SET_GROUP);
-
- task_rq_unlock(rq, task, &rf);
-}
-
static int cpu_cgroup_can_attach(struct cgroup_taskset *tset)
{
struct task_struct *task;
@@ -11134,7 +11116,6 @@ struct cgroup_subsys cpu_cgrp_subsys = {
.css_released = cpu_cgroup_css_released,
.css_free = cpu_cgroup_css_free,
.css_extra_stat_show = cpu_extra_stat_show,
- .fork = cpu_cgroup_fork,
.can_attach = cpu_cgroup_can_attach,
.attach = cpu_cgroup_attach,
.legacy_cftypes = cpu_legacy_files,
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 2a3e12ead144..8992ce5e73d2 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -11539,14 +11539,6 @@ static void attach_entity_cfs_rq(struct sched_entity *se)
{
struct cfs_rq *cfs_rq = cfs_rq_of(se);
-#ifdef CONFIG_FAIR_GROUP_SCHED
- /*
- * Since the real-depth could have been changed (only FAIR
- * class maintain depth value), reset depth properly.
- */
- se->depth = se->parent ? se->parent->depth + 1 : 0;
-#endif
-
/* Synchronize entity with its cfs_rq */
update_load_avg(cfs_rq, se, sched_feat(ATTACH_AGE_LOAD) ? 0 : SKIP_AGE_LOAD);
attach_entity_load_avg(cfs_rq, se);
@@ -11642,15 +11634,7 @@ void init_cfs_rq(struct cfs_rq *cfs_rq)
}
#ifdef CONFIG_FAIR_GROUP_SCHED
-static void task_set_group_fair(struct task_struct *p)
-{
- struct sched_entity *se = &p->se;
-
- set_task_rq(p, task_cpu(p));
- se->depth = se->parent ? se->parent->depth + 1 : 0;
-}
-
-static void task_move_group_fair(struct task_struct *p)
+static void task_change_group_fair(struct task_struct *p)
{
detach_task_cfs_rq(p);
set_task_rq(p, task_cpu(p));
@@ -11662,19 +11646,6 @@ static void task_move_group_fair(struct task_struct *p)
attach_task_cfs_rq(p);
}
-static void task_change_group_fair(struct task_struct *p, int type)
-{
- switch (type) {
- case TASK_SET_GROUP:
- task_set_group_fair(p);
- break;
-
- case TASK_MOVE_GROUP:
- task_move_group_fair(p);
- break;
- }
-}
-
void free_fair_sched_group(struct task_group *tg)
{
int i;
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index aad7f5ee9666..19e0076e4245 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1940,6 +1940,7 @@ static inline void set_task_rq(struct task_struct *p, unsigned int cpu)
set_task_rq_fair(&p->se, p->se.cfs_rq, tg->cfs_rq[cpu]);
p->se.cfs_rq = tg->cfs_rq[cpu];
p->se.parent = tg->se[cpu];
+ p->se.depth = tg->se[cpu] ? tg->se[cpu]->depth + 1 : 0;
#endif
#ifdef CONFIG_RT_GROUP_SCHED
@@ -2202,11 +2203,8 @@ struct sched_class {
void (*update_curr)(struct rq *rq);
-#define TASK_SET_GROUP 0
-#define TASK_MOVE_GROUP 1
-
#ifdef CONFIG_FAIR_GROUP_SCHED
- void (*task_change_group)(struct task_struct *p, int type);
+ void (*task_change_group)(struct task_struct *p);
#endif
};
--
2.36.1
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