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Message-ID: <20251022205629.845930-4-tj@kernel.org>
Date: Wed, 22 Oct 2025 10:56:29 -1000
From: Tejun Heo <tj@...nel.org>
To: void@...ifault.com,
arighi@...dia.com,
changwoo@...lia.com
Cc: linux-kernel@...r.kernel.org,
sched-ext@...ts.linux.dev,
peterz@...radead.org,
Tejun Heo <tj@...nel.org>
Subject: [PATCH RESEND v2 3/3] sched_ext: Rename pnt_seq to kick_sync
The pnt_seq field and related infrastructure were originally named for
"pick next task sequence", reflecting their original implementation in
scx_next_task_picked(). However, the sequence counter is now incremented in
both put_prev_task_scx() and pick_task_scx() and its purpose is to
synchronize kick operations via SCX_KICK_WAIT, not specifically to track
pick_next_task events.
Rename to better reflect the actual semantics:
- pnt_seq -> kick_sync
- scx_kick_pseqs -> scx_kick_syncs
- pseqs variables -> ksyncs
- Update comments to refer to "kick_sync sequence" instead of "pick_task
sequence"
This is a pure renaming with no functional changes.
Signed-off-by: Tejun Heo <tj@...nel.org>
---
kernel/sched/ext.c | 80 ++++++++++++++++++++++++++--------------------------
kernel/sched/sched.h | 2 +-
2 files changed, 41 insertions(+), 41 deletions(-)
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -68,18 +68,18 @@ static unsigned long scx_watchdog_timest
static struct delayed_work scx_watchdog_work;
/*
- * For %SCX_KICK_WAIT: Each CPU has a pointer to an array of pick_task sequence
+ * For %SCX_KICK_WAIT: Each CPU has a pointer to an array of kick_sync sequence
* numbers. The arrays are allocated with kvzalloc() as size can exceed percpu
* allocator limits on large machines. O(nr_cpu_ids^2) allocation, allocated
* lazily when enabling and freed when disabling to avoid waste when sched_ext
* isn't active.
*/
-struct scx_kick_pseqs {
+struct scx_kick_syncs {
struct rcu_head rcu;
- unsigned long seqs[];
+ unsigned long syncs[];
};
-static DEFINE_PER_CPU(struct scx_kick_pseqs __rcu *, scx_kick_pseqs);
+static DEFINE_PER_CPU(struct scx_kick_syncs __rcu *, scx_kick_syncs);
/*
* Direct dispatch marker.
@@ -2301,7 +2301,7 @@ static void put_prev_task_scx(struct rq
struct scx_sched *sch = scx_root;
/* see kick_cpus_irq_workfn() */
- smp_store_release(&rq->scx.pnt_seq, rq->scx.pnt_seq + 1);
+ smp_store_release(&rq->scx.kick_sync, rq->scx.kick_sync + 1);
update_curr_scx(rq);
@@ -2357,7 +2357,7 @@ do_pick_task_scx(struct rq *rq, struct r
struct task_struct *p;
/* see kick_cpus_irq_workfn() */
- smp_store_release(&rq->scx.pnt_seq, rq->scx.pnt_seq + 1);
+ smp_store_release(&rq->scx.kick_sync, rq->scx.kick_sync + 1);
rq_modified_clear(rq);
@@ -3883,24 +3883,24 @@ static const char *scx_exit_reason(enum
}
}
-static void free_kick_pseqs_rcu(struct rcu_head *rcu)
+static void free_kick_syncs_rcu(struct rcu_head *rcu)
{
- struct scx_kick_pseqs *pseqs = container_of(rcu, struct scx_kick_pseqs, rcu);
+ struct scx_kick_syncs *ksyncs = container_of(rcu, struct scx_kick_syncs, rcu);
- kvfree(pseqs);
+ kvfree(ksyncs);
}
-static void free_kick_pseqs(void)
+static void free_kick_syncs(void)
{
int cpu;
for_each_possible_cpu(cpu) {
- struct scx_kick_pseqs **pseqs = per_cpu_ptr(&scx_kick_pseqs, cpu);
- struct scx_kick_pseqs *to_free;
+ struct scx_kick_syncs **ksyncs = per_cpu_ptr(&scx_kick_syncs, cpu);
+ struct scx_kick_syncs *to_free;
- to_free = rcu_replace_pointer(*pseqs, NULL, true);
+ to_free = rcu_replace_pointer(*ksyncs, NULL, true);
if (to_free)
- call_rcu(&to_free->rcu, free_kick_pseqs_rcu);
+ call_rcu(&to_free->rcu, free_kick_syncs_rcu);
}
}
@@ -4038,7 +4038,7 @@ static void scx_disable_workfn(struct kt
free_percpu(scx_dsp_ctx);
scx_dsp_ctx = NULL;
scx_dsp_max_batch = 0;
- free_kick_pseqs();
+ free_kick_syncs();
mutex_unlock(&scx_enable_mutex);
@@ -4287,10 +4287,10 @@ static void scx_dump_state(struct scx_ex
seq_buf_init(&ns, buf, avail);
dump_newline(&ns);
- dump_line(&ns, "CPU %-4d: nr_run=%u flags=0x%x cpu_rel=%d ops_qseq=%lu pnt_seq=%lu",
+ dump_line(&ns, "CPU %-4d: nr_run=%u flags=0x%x cpu_rel=%d ops_qseq=%lu ksync=%lu",
cpu, rq->scx.nr_running, rq->scx.flags,
rq->scx.cpu_released, rq->scx.ops_qseq,
- rq->scx.pnt_seq);
+ rq->scx.kick_sync);
dump_line(&ns, " curr=%s[%d] class=%ps",
rq->curr->comm, rq->curr->pid,
rq->curr->sched_class);
@@ -4401,7 +4401,7 @@ static void scx_vexit(struct scx_sched *
irq_work_queue(&sch->error_irq_work);
}
-static int alloc_kick_pseqs(void)
+static int alloc_kick_syncs(void)
{
int cpu;
@@ -4410,19 +4410,19 @@ static int alloc_kick_pseqs(void)
* can exceed percpu allocator limits on large machines.
*/
for_each_possible_cpu(cpu) {
- struct scx_kick_pseqs **pseqs = per_cpu_ptr(&scx_kick_pseqs, cpu);
- struct scx_kick_pseqs *new_pseqs;
+ struct scx_kick_syncs **ksyncs = per_cpu_ptr(&scx_kick_syncs, cpu);
+ struct scx_kick_syncs *new_ksyncs;
- WARN_ON_ONCE(rcu_access_pointer(*pseqs));
+ WARN_ON_ONCE(rcu_access_pointer(*ksyncs));
- new_pseqs = kvzalloc_node(struct_size(new_pseqs, seqs, nr_cpu_ids),
- GFP_KERNEL, cpu_to_node(cpu));
- if (!new_pseqs) {
- free_kick_pseqs();
+ new_ksyncs = kvzalloc_node(struct_size(new_ksyncs, syncs, nr_cpu_ids),
+ GFP_KERNEL, cpu_to_node(cpu));
+ if (!new_ksyncs) {
+ free_kick_syncs();
return -ENOMEM;
}
- rcu_assign_pointer(*pseqs, new_pseqs);
+ rcu_assign_pointer(*ksyncs, new_ksyncs);
}
return 0;
@@ -4578,14 +4578,14 @@ static int scx_enable(struct sched_ext_o
goto err_unlock;
}
- ret = alloc_kick_pseqs();
+ ret = alloc_kick_syncs();
if (ret)
goto err_unlock;
sch = scx_alloc_and_add_sched(ops);
if (IS_ERR(sch)) {
ret = PTR_ERR(sch);
- goto err_free_pseqs;
+ goto err_free_ksyncs;
}
/*
@@ -4788,8 +4788,8 @@ static int scx_enable(struct sched_ext_o
return 0;
-err_free_pseqs:
- free_kick_pseqs();
+err_free_ksyncs:
+ free_kick_syncs();
err_unlock:
mutex_unlock(&scx_enable_mutex);
return ret;
@@ -5119,7 +5119,7 @@ static bool can_skip_idle_kick(struct rq
return !is_idle_task(rq->curr) && !(rq->scx.flags & SCX_RQ_IN_BALANCE);
}
-static bool kick_one_cpu(s32 cpu, struct rq *this_rq, unsigned long *pseqs)
+static bool kick_one_cpu(s32 cpu, struct rq *this_rq, unsigned long *ksyncs)
{
struct rq *rq = cpu_rq(cpu);
struct scx_rq *this_scx = &this_rq->scx;
@@ -5146,7 +5146,7 @@ static bool kick_one_cpu(s32 cpu, struct
if (cpumask_test_cpu(cpu, this_scx->cpus_to_wait)) {
if (cur_class == &ext_sched_class) {
- pseqs[cpu] = rq->scx.pnt_seq;
+ ksyncs[cpu] = rq->scx.kick_sync;
should_wait = true;
} else {
cpumask_clear_cpu(cpu, this_scx->cpus_to_wait);
@@ -5182,20 +5182,20 @@ static void kick_cpus_irq_workfn(struct
{
struct rq *this_rq = this_rq();
struct scx_rq *this_scx = &this_rq->scx;
- struct scx_kick_pseqs __rcu *pseqs_pcpu = __this_cpu_read(scx_kick_pseqs);
+ struct scx_kick_syncs __rcu *ksyncs_pcpu = __this_cpu_read(scx_kick_syncs);
bool should_wait = false;
- unsigned long *pseqs;
+ unsigned long *ksyncs;
s32 cpu;
- if (unlikely(!pseqs_pcpu)) {
- pr_warn_once("kick_cpus_irq_workfn() called with NULL scx_kick_pseqs");
+ if (unlikely(!ksyncs_pcpu)) {
+ pr_warn_once("kick_cpus_irq_workfn() called with NULL scx_kick_syncs");
return;
}
- pseqs = rcu_dereference_bh(pseqs_pcpu)->seqs;
+ ksyncs = rcu_dereference_bh(ksyncs_pcpu)->syncs;
for_each_cpu(cpu, this_scx->cpus_to_kick) {
- should_wait |= kick_one_cpu(cpu, this_rq, pseqs);
+ should_wait |= kick_one_cpu(cpu, this_rq, ksyncs);
cpumask_clear_cpu(cpu, this_scx->cpus_to_kick);
cpumask_clear_cpu(cpu, this_scx->cpus_to_kick_if_idle);
}
@@ -5209,7 +5209,7 @@ static void kick_cpus_irq_workfn(struct
return;
for_each_cpu(cpu, this_scx->cpus_to_wait) {
- unsigned long *wait_pnt_seq = &cpu_rq(cpu)->scx.pnt_seq;
+ unsigned long *wait_kick_sync = &cpu_rq(cpu)->scx.kick_sync;
/*
* Busy-wait until the task running at the time of kicking is no
@@ -5223,7 +5223,7 @@ static void kick_cpus_irq_workfn(struct
* the wait when $cpu is taken by a higher sched class.
*/
if (cpu != cpu_of(this_rq))
- smp_cond_load_acquire(wait_pnt_seq, VAL != pseqs[cpu]);
+ smp_cond_load_acquire(wait_kick_sync, VAL != ksyncs[cpu]);
cpumask_clear_cpu(cpu, this_scx->cpus_to_wait);
}
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -803,7 +803,7 @@ struct scx_rq {
cpumask_var_t cpus_to_kick_if_idle;
cpumask_var_t cpus_to_preempt;
cpumask_var_t cpus_to_wait;
- unsigned long pnt_seq;
+ unsigned long kick_sync;
struct balance_callback deferred_bal_cb;
struct irq_work deferred_irq_work;
struct irq_work kick_cpus_irq_work;
--
2.47.1
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