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Message-ID: <20251206001451.1418225-1-jstultz@google.com>
Date: Sat, 6 Dec 2025 00:14:45 +0000
From: John Stultz <jstultz@...gle.com>
To: LKML <linux-kernel@...r.kernel.org>
Cc: John Stultz <jstultz@...gle.com>, Joel Fernandes <joelaf@...gle.com>,
Qais Yousef <qyousef@...alina.io>, Ingo Molnar <mingo@...hat.com>,
Peter Zijlstra <peterz@...radead.org>, Juri Lelli <juri.lelli@...hat.com>,
Vincent Guittot <vincent.guittot@...aro.org>, Dietmar Eggemann <dietmar.eggemann@....com>,
Valentin Schneider <vschneid@...hat.com>, Steven Rostedt <rostedt@...dmis.org>,
Ben Segall <bsegall@...gle.com>, Zimuzo Ezeozue <zezeozue@...gle.com>, Mel Gorman <mgorman@...e.de>,
Will Deacon <will@...nel.org>, Waiman Long <longman@...hat.com>, Boqun Feng <boqun.feng@...il.com>,
"Paul E. McKenney" <paulmck@...nel.org>, Metin Kaya <Metin.Kaya@....com>,
Xuewen Yan <xuewen.yan94@...il.com>, K Prateek Nayak <kprateek.nayak@....com>,
Thomas Gleixner <tglx@...utronix.de>, Daniel Lezcano <daniel.lezcano@...aro.org>,
Tejun Heo <tj@...nel.org>, David Vernet <void@...ifault.com>, Andrea Righi <arighi@...dia.com>,
Changwoo Min <changwoo@...lia.com>, sched-ext@...ts.linux.dev, kernel-team@...roid.com
Subject: [RFC][PATCH] sched/ext: Split curr|donor references properly
With proxy-exec, we want to do the accounting against the donor
most of the time. Without proxy-exec, there should be no
difference as the rq->donor and rq->curr are the same.
So rework the logic to reference the rq->donor where appropriate.
Also add donor info to scx_dump_state()
Since CONFIG_SCHED_PROXY_EXEC currently depends on
!CONFIG_SCHED_CLASS_EXT, this should have no effect
(other then the extra donor output in scx_dump_state),
but this is one step needed to eventually remove that
constraint for proxy-exec.
Just wanted to send this out for early review prior to LPC.
Feedback or thoughts would be greatly appreciated!
Signed-off-by: John Stultz <jstultz@...gle.com>
---
Cc: Joel Fernandes <joelaf@...gle.com>
Cc: Qais Yousef <qyousef@...alina.io>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Juri Lelli <juri.lelli@...hat.com>
Cc: Vincent Guittot <vincent.guittot@...aro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@....com>
Cc: Valentin Schneider <vschneid@...hat.com>
Cc: Steven Rostedt <rostedt@...dmis.org>
Cc: Ben Segall <bsegall@...gle.com>
Cc: Zimuzo Ezeozue <zezeozue@...gle.com>
Cc: Mel Gorman <mgorman@...e.de>
Cc: Will Deacon <will@...nel.org>
Cc: Waiman Long <longman@...hat.com>
Cc: Boqun Feng <boqun.feng@...il.com>
Cc: "Paul E. McKenney" <paulmck@...nel.org>
Cc: Metin Kaya <Metin.Kaya@....com>
Cc: Xuewen Yan <xuewen.yan94@...il.com>
Cc: K Prateek Nayak <kprateek.nayak@....com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Daniel Lezcano <daniel.lezcano@...aro.org>
Cc: Tejun Heo <tj@...nel.org>
Cc: David Vernet <void@...ifault.com>
Cc: Andrea Righi <arighi@...dia.com>
Cc: Changwoo Min <changwoo@...lia.com>
Cc: sched-ext@...ts.linux.dev
Cc: kernel-team@...roid.com
---
kernel/sched/ext.c | 31 +++++++++++++++++--------------
1 file changed, 17 insertions(+), 14 deletions(-)
diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 05f5a49e9649a..446091cba4429 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -938,17 +938,17 @@ static void touch_core_sched_dispatch(struct rq *rq, struct task_struct *p)
static void update_curr_scx(struct rq *rq)
{
- struct task_struct *curr = rq->curr;
+ struct task_struct *donor = rq->donor;
s64 delta_exec;
delta_exec = update_curr_common(rq);
if (unlikely(delta_exec <= 0))
return;
- if (curr->scx.slice != SCX_SLICE_INF) {
- curr->scx.slice -= min_t(u64, curr->scx.slice, delta_exec);
- if (!curr->scx.slice)
- touch_core_sched(rq, curr);
+ if (donor->scx.slice != SCX_SLICE_INF) {
+ donor->scx.slice -= min_t(u64, donor->scx.slice, delta_exec);
+ if (!donor->scx.slice)
+ touch_core_sched(rq, donor);
}
}
@@ -1090,14 +1090,14 @@ static void dispatch_enqueue(struct scx_sched *sch, struct scx_dispatch_q *dsq,
struct rq *rq = container_of(dsq, struct rq, scx.local_dsq);
bool preempt = false;
- if ((enq_flags & SCX_ENQ_PREEMPT) && p != rq->curr &&
- rq->curr->sched_class == &ext_sched_class) {
- rq->curr->scx.slice = 0;
+ if ((enq_flags & SCX_ENQ_PREEMPT) && p != rq->donor &&
+ rq->donor->sched_class == &ext_sched_class) {
+ rq->donor->scx.slice = 0;
preempt = true;
}
if (preempt || sched_class_above(&ext_sched_class,
- rq->curr->sched_class))
+ rq->donor->sched_class))
resched_curr(rq);
} else {
raw_spin_unlock(&dsq->lock);
@@ -2001,7 +2001,7 @@ static void dispatch_to_local_dsq(struct scx_sched *sch, struct rq *rq,
}
/* if the destination CPU is idle, wake it up */
- if (sched_class_above(p->sched_class, dst_rq->curr->sched_class))
+ if (sched_class_above(p->sched_class, dst_rq->donor->sched_class))
resched_curr(dst_rq);
}
@@ -2424,7 +2424,7 @@ static struct task_struct *first_local_task(struct rq *rq)
static struct task_struct *
do_pick_task_scx(struct rq *rq, struct rq_flags *rf, bool force_scx)
{
- struct task_struct *prev = rq->curr;
+ struct task_struct *prev = rq->donor;
bool keep_prev, kick_idle = false;
struct task_struct *p;
@@ -3093,7 +3093,7 @@ int scx_check_setscheduler(struct task_struct *p, int policy)
#ifdef CONFIG_NO_HZ_FULL
bool scx_can_stop_tick(struct rq *rq)
{
- struct task_struct *p = rq->curr;
+ struct task_struct *p = rq->donor;
if (scx_rq_bypassing(rq))
return false;
@@ -4587,6 +4587,9 @@ static void scx_dump_state(struct scx_exit_info *ei, size_t dump_len)
dump_line(&ns, " curr=%s[%d] class=%ps",
rq->curr->comm, rq->curr->pid,
rq->curr->sched_class);
+ dump_line(&ns, " donor=%s[%d] class=%ps",
+ rq->donor->comm, rq->donor->pid,
+ rq->donor->sched_class);
if (!cpumask_empty(rq->scx.cpus_to_kick))
dump_line(&ns, " cpus_to_kick : %*pb",
cpumask_pr_args(rq->scx.cpus_to_kick));
@@ -5426,7 +5429,7 @@ static bool kick_one_cpu(s32 cpu, struct rq *this_rq, unsigned long *ksyncs)
unsigned long flags;
raw_spin_rq_lock_irqsave(rq, flags);
- cur_class = rq->curr->sched_class;
+ cur_class = rq->donor->sched_class;
/*
* During CPU hotplug, a CPU may depend on kicking itself to make
@@ -5438,7 +5441,7 @@ static bool kick_one_cpu(s32 cpu, struct rq *this_rq, unsigned long *ksyncs)
!sched_class_above(cur_class, &ext_sched_class)) {
if (cpumask_test_cpu(cpu, this_scx->cpus_to_preempt)) {
if (cur_class == &ext_sched_class)
- rq->curr->scx.slice = 0;
+ rq->donor->scx.slice = 0;
cpumask_clear_cpu(cpu, this_scx->cpus_to_preempt);
}
--
2.52.0.223.gf5cc29aaa4-goog
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