From: Peter Zijlstra <peterz@infradead.org>
To: mingo@kernel.org
Cc: peterz@infradead.org, juri.lelli@redhat.com,
vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
vschneid@redhat.com, tj@kernel.org, void@manifault.com,
linux-kernel@vger.kernel.org
Subject: [RFC][PATCH 6/6] sched: Cleanup sched_delayed handling for class switches
Date: Wed, 30 Oct 2024 16:13:01 +0100 [thread overview]
Message-ID: <20241030152142.928034708@infradead.org> (raw)
In-Reply-To: 20241030151255.300069509@infradead.org
Use the new sched_class::switching_from() method to dequeue delayed
tasks before switching to another class.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
kernel/sched/core.c | 12 ++++++++----
kernel/sched/ext.c | 12 ++++--------
kernel/sched/fair.c | 7 +++++++
kernel/sched/syscalls.c | 3 ---
4 files changed, 19 insertions(+), 15 deletions(-)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7139,9 +7139,6 @@ void rt_mutex_setprio(struct task_struct
if (prev_class != next_class)
queue_flag |= DEQUEUE_CLASS;
- if (prev_class != next_class && p->se.sched_delayed)
- dequeue_task(rq, p, DEQUEUE_SLEEP | DEQUEUE_DELAYED | DEQUEUE_NOCLOCK);
-
scoped_guard (sched_change, p, queue_flag) {
/*
* Boosting condition are:
@@ -10530,8 +10527,15 @@ struct sched_change_ctx sched_change_beg
lockdep_assert_rq_held(rq);
- if ((flags & DEQUEUE_CLASS) && p->sched_class->switching_from)
+ if ((flags & DEQUEUE_CLASS) && p->sched_class->switching_from) {
+ /*
+ * switching_from_fair() assumes CLASS implies NOCLOCK; fixing
+ * this assumption would mean switching_from() would need to be
+ * able to change flags.
+ */
+ SCHED_WARN_ON(!(flags & DEQUEUE_NOCLOCK));
p->sched_class->switching_from(rq, p, flags);
+ }
struct sched_change_ctx ctx = {
.p = p,
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -4485,7 +4485,7 @@ static void scx_ops_disable_workfn(struc
scx_task_iter_start(&sti);
while ((p = scx_task_iter_next_locked(&sti))) {
- unsigned int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE;
+ unsigned int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK;
const struct sched_class *old_class = p->sched_class;
const struct sched_class *new_class =
__setscheduler_class(p->policy, p->prio);
@@ -4493,9 +4493,7 @@ static void scx_ops_disable_workfn(struc
if (old_class != new_class)
queue_flags |= DEQUEUE_CLASS;
- if (old_class != new_class && p->se.sched_delayed)
- dequeue_task(task_rq(p), p, DEQUEUE_SLEEP | DEQUEUE_DELAYED);
-
+ update_rq_clock(task_rq(p));
scoped_guard (sched_change, p, queue_flags) {
p->sched_class = new_class;
}
@@ -5202,7 +5200,7 @@ static int scx_ops_enable(struct sched_e
percpu_down_write(&scx_fork_rwsem);
scx_task_iter_start(&sti);
while ((p = scx_task_iter_next_locked(&sti))) {
- unsigned int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE;
+ unsigned int queue_flags = DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK;
const struct sched_class *old_class = p->sched_class;
const struct sched_class *new_class =
__setscheduler_class(p->policy, p->prio);
@@ -5210,9 +5208,7 @@ static int scx_ops_enable(struct sched_e
if (old_class != new_class)
queue_flags |= DEQUEUE_CLASS;
- if (old_class != new_class && p->se.sched_delayed)
- dequeue_task(task_rq(p), p, DEQUEUE_SLEEP | DEQUEUE_DELAYED);
-
+ update_rq_clock(task_rq(p));
scoped_guard (sched_change, p, DEQUEUE_SAVE | DEQUEUE_MOVE) {
p->scx.slice = SCX_SLICE_DFL;
p->sched_class = new_class;
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -13175,6 +13175,12 @@ static void attach_task_cfs_rq(struct ta
attach_entity_cfs_rq(se);
}
+static void switching_from_fair(struct rq *rq, struct task_struct *p, int flags)
+{
+ if ((flags & DEQUEUE_CLASS) && p->se.sched_delayed)
+ dequeue_task(rq, p, DEQUEUE_SLEEP | DEQUEUE_DELAYED | DEQUEUE_NOCLOCK);
+}
+
static void switched_from_fair(struct rq *rq, struct task_struct *p, int flags)
{
detach_task_cfs_rq(p);
@@ -13592,6 +13598,7 @@ DEFINE_SCHED_CLASS(fair) = {
.reweight_task = reweight_task_fair,
.prio_changed = prio_changed_fair,
+ .switching_from = switching_from_fair,
.switched_from = switched_from_fair,
.switched_to = switched_to_fair,
--- a/kernel/sched/syscalls.c
+++ b/kernel/sched/syscalls.c
@@ -701,9 +701,6 @@ int __sched_setscheduler(struct task_str
if (prev_class != next_class)
queue_flags |= DEQUEUE_CLASS;
- if (prev_class != next_class && p->se.sched_delayed)
- dequeue_task(rq, p, DEQUEUE_SLEEP | DEQUEUE_DELAYED | DEQUEUE_NOCLOCK);
-
scoped_guard (sched_change, p, queue_flags) {
if (!(attr->sched_flags & SCHED_FLAG_KEEP_PARAMS)) {
next prev parent reply other threads:[~2024-10-30 15:25 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-10-30 15:12 [RFC][PATCH 0/6] clean up class switching Peter Zijlstra
2024-10-30 15:12 ` [PATCH 1/6] sched/ext: Fix scx vs sched_delayed Peter Zijlstra
2024-10-30 15:50 ` Christian Loehle
2024-10-30 15:54 ` Peter Zijlstra
2024-10-30 17:17 ` Christian Loehle
2024-10-30 20:19 ` Tejun Heo
2024-10-30 15:12 ` [RFC][PATCH 2/6] sched: Employ sched_change guards Peter Zijlstra
2024-10-30 20:58 ` Tejun Heo
2024-10-30 21:09 ` Tejun Heo
2024-10-30 21:11 ` Peter Zijlstra
2024-10-30 15:12 ` [RFC][PATCH 3/6] sched: Re-arrange the {EN,DE}QUEUE flags Peter Zijlstra
2024-10-30 15:12 ` [RFC][PATCH 4/6] sched: Fold sched_class::switch{ing,ed}_{to,from}() into the change pattern Peter Zijlstra
2024-10-30 21:12 ` Tejun Heo
2024-10-30 21:15 ` Peter Zijlstra
2024-10-30 21:29 ` Tejun Heo
2024-10-30 21:37 ` Peter Zijlstra
2024-10-30 21:39 ` Tejun Heo
2024-10-30 15:13 ` [RFC][PATCH 5/6] sched: Add flags to the switch{ing,ed}_{to,from}() methods Peter Zijlstra
2024-10-30 15:13 ` Peter Zijlstra [this message]
2024-10-30 15:45 ` [RFC][PATCH 6/6] sched: Cleanup sched_delayed handling for class switches Peter Zijlstra
2024-10-30 21:27 ` Tejun Heo
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20241030152142.928034708@infradead.org \
--to=peterz@infradead.org \
--cc=bsegall@google.com \
--cc=dietmar.eggemann@arm.com \
--cc=juri.lelli@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mgorman@suse.de \
--cc=mingo@kernel.org \
--cc=rostedt@goodmis.org \
--cc=tj@kernel.org \
--cc=vincent.guittot@linaro.org \
--cc=void@manifault.com \
--cc=vschneid@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox