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Message-ID: <Yxhkhn55uHZx+NGl@hirez.programming.kicks-ass.net>
Date: Wed, 7 Sep 2022 11:29:42 +0200
From: Peter Zijlstra <peterz@...radead.org>
To: Ingo Molnar <mingo@...nel.org>
Cc: rjw@...ysocki.net, oleg@...hat.com, vincent.guittot@...aro.org,
dietmar.eggemann@....com, rostedt@...dmis.org, mgorman@...e.de,
ebiederm@...ssion.com, bigeasy@...utronix.de,
Will Deacon <will@...nel.org>, linux-kernel@...r.kernel.org,
tj@...nel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH v3 3/6] sched: Change wait_task_inactive()s match_state
On Tue, Sep 06, 2022 at 12:54:34PM +0200, Peter Zijlstra wrote:
> > Suggestion #1:
> >
> > - Shouldn't we rename task_running() to something like task_on_cpu()? The
> > task_running() primitive is similar to TASK_RUNNING but is not based off
> > any TASK_FLAGS.
>
> That looks like a simple enough patch, lemme go do that.
---
Subject: sched: Rename task_running() to task_on_cpu()
From: Peter Zijlstra <peterz@...radead.org>
Date: Tue Sep 6 12:33:04 CEST 2022
There is some ambiguity about task_running() in that it is unrelated
to TASK_RUNNING but instead tests ->on_cpu. As such, rename the thing
task_on_cpu().
Suggested-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
---
kernel/sched/core.c | 10 +++++-----
kernel/sched/core_sched.c | 2 +-
kernel/sched/deadline.c | 6 +++---
kernel/sched/fair.c | 2 +-
kernel/sched/rt.c | 6 +++---
kernel/sched/sched.h | 2 +-
6 files changed, 14 insertions(+), 14 deletions(-)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -2778,7 +2778,7 @@ static int affine_move_task(struct rq *r
return -EINVAL;
}
- if (task_running(rq, p) || READ_ONCE(p->__state) == TASK_WAKING) {
+ if (task_on_cpu(rq, p) || READ_ONCE(p->__state) == TASK_WAKING) {
/*
* MIGRATE_ENABLE gets here because 'p == current', but for
* anything else we cannot do is_migration_disabled(), punt
@@ -3290,11 +3290,11 @@ unsigned long wait_task_inactive(struct
*
* NOTE! Since we don't hold any locks, it's not
* even sure that "rq" stays as the right runqueue!
- * But we don't care, since "task_running()" will
+ * But we don't care, since "task_on_cpu()" will
* return false if the runqueue has changed and p
* is actually now running somewhere else!
*/
- while (task_running(rq, p)) {
+ while (task_on_cpu(rq, p)) {
if (match_state && unlikely(READ_ONCE(p->__state) != match_state))
return 0;
cpu_relax();
@@ -3307,7 +3307,7 @@ unsigned long wait_task_inactive(struct
*/
rq = task_rq_lock(p, &rf);
trace_sched_wait_task(p);
- running = task_running(rq, p);
+ running = task_on_cpu(rq, p);
queued = task_on_rq_queued(p);
ncsw = 0;
if (!match_state || READ_ONCE(p->__state) == match_state)
@@ -8649,7 +8649,7 @@ int __sched yield_to(struct task_struct
if (curr->sched_class != p->sched_class)
goto out_unlock;
- if (task_running(p_rq, p) || !task_is_running(p))
+ if (task_on_cpu(p_rq, p) || !task_is_running(p))
goto out_unlock;
yielded = curr->sched_class->yield_to_task(rq, p);
--- a/kernel/sched/core_sched.c
+++ b/kernel/sched/core_sched.c
@@ -88,7 +88,7 @@ static unsigned long sched_core_update_c
* core has now entered/left forced idle state. Defer accounting to the
* next scheduling edge, rather than always forcing a reschedule here.
*/
- if (task_running(rq, p))
+ if (task_on_cpu(rq, p))
resched_curr(rq);
task_rq_unlock(rq, p, &rf);
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -2087,7 +2087,7 @@ static void task_fork_dl(struct task_str
static int pick_dl_task(struct rq *rq, struct task_struct *p, int cpu)
{
- if (!task_running(rq, p) &&
+ if (!task_on_cpu(rq, p) &&
cpumask_test_cpu(cpu, &p->cpus_mask))
return 1;
return 0;
@@ -2241,7 +2241,7 @@ static struct rq *find_lock_later_rq(str
if (double_lock_balance(rq, later_rq)) {
if (unlikely(task_rq(task) != rq ||
!cpumask_test_cpu(later_rq->cpu, &task->cpus_mask) ||
- task_running(rq, task) ||
+ task_on_cpu(rq, task) ||
!dl_task(task) ||
!task_on_rq_queued(task))) {
double_unlock_balance(rq, later_rq);
@@ -2475,7 +2475,7 @@ static void pull_dl_task(struct rq *this
*/
static void task_woken_dl(struct rq *rq, struct task_struct *p)
{
- if (!task_running(rq, p) &&
+ if (!task_on_cpu(rq, p) &&
!test_tsk_need_resched(rq->curr) &&
p->nr_cpus_allowed > 1 &&
dl_task(rq->curr) &&
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -7938,7 +7938,7 @@ int can_migrate_task(struct task_struct
/* Record that we found at least one task that could run on dst_cpu */
env->flags &= ~LBF_ALL_PINNED;
- if (task_running(env->src_rq, p)) {
+ if (task_on_cpu(env->src_rq, p)) {
schedstat_inc(p->stats.nr_failed_migrations_running);
return 0;
}
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1849,7 +1849,7 @@ static void put_prev_task_rt(struct rq *
static int pick_rt_task(struct rq *rq, struct task_struct *p, int cpu)
{
- if (!task_running(rq, p) &&
+ if (!task_on_cpu(rq, p) &&
cpumask_test_cpu(cpu, &p->cpus_mask))
return 1;
@@ -2004,7 +2004,7 @@ static struct rq *find_lock_lowest_rq(st
*/
if (unlikely(task_rq(task) != rq ||
!cpumask_test_cpu(lowest_rq->cpu, &task->cpus_mask) ||
- task_running(rq, task) ||
+ task_on_cpu(rq, task) ||
!rt_task(task) ||
!task_on_rq_queued(task))) {
@@ -2462,7 +2462,7 @@ static void pull_rt_task(struct rq *this
*/
static void task_woken_rt(struct rq *rq, struct task_struct *p)
{
- bool need_to_push = !task_running(rq, p) &&
+ bool need_to_push = !task_on_cpu(rq, p) &&
!test_tsk_need_resched(rq->curr) &&
p->nr_cpus_allowed > 1 &&
(dl_task(rq->curr) || rt_task(rq->curr)) &&
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -2060,7 +2060,7 @@ static inline int task_current(struct rq
return rq->curr == p;
}
-static inline int task_running(struct rq *rq, struct task_struct *p)
+static inline int task_on_cpu(struct rq *rq, struct task_struct *p)
{
#ifdef CONFIG_SMP
return p->on_cpu;
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