[PATCH 0/2] rename var for slice refill event and add helper

[PATCH 0/2] rename var for slice refill event and add helper

[Honglei Wang]

SCX_EV_ENQ_SLICE_DFL gives the impression that the event only occurs
when the tasks were enqueued, which seems not accurate. So rename the
variable to SCX_EV_REFILL_SLICE_DFL.

The slice refilling with default slice always come with event
statistics together, add a helper routine to make it cleaner.

Honglei Wang (2):
  sched_ext: change the variable name for slice refill event
  sched_ext: add helper for refill task with default slice

 kernel/sched/ext.c             | 36 +++++++++++++++++-----------------
 tools/sched_ext/scx_qmap.bpf.c |  4 ++--
 2 files changed, 20 insertions(+), 20 deletions(-)

-- 
2.45.2

[PATCH 1/2] sched_ext: change the variable name for slice refill event

[Honglei Wang]

SCX_EV_ENQ_SLICE_DFL gives the impression that the event only occurs
when the tasks were enqueued, which seems not accurate. What it actually
means is the refilling with defalt slice, and this can occur either when
enqueue or pick_task. Let's change the variable to
SCX_EV_REFILL_SLICE_DFL.

Signed-off-by: Honglei Wang <jameshongleiwang@126.com>
---
 kernel/sched/ext.c             | 22 +++++++++++-----------
 tools/sched_ext/scx_qmap.bpf.c |  4 ++--
 2 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 66bcd40a28ca..594087ac4c9e 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -1517,10 +1517,10 @@ struct scx_event_stats {
 	s64		SCX_EV_ENQ_SKIP_MIGRATION_DISABLED;
 
 	/*
-	 * The total number of tasks enqueued (or pick_task-ed) with a
-	 * default time slice (SCX_SLICE_DFL).
+	 * The total number of tasks slice refill with default time slice
+	 * (SCX_SLICE_DFL).
 	 */
-	s64		SCX_EV_ENQ_SLICE_DFL;
+	s64		SCX_EV_REFILL_SLICE_DFL;
 
 	/*
 	 * The total duration of bypass modes in nanoseconds.
@@ -2197,7 +2197,7 @@ static void do_enqueue_task(struct rq *rq, struct task_struct *p, u64 enq_flags,
 	 */
 	touch_core_sched(rq, p);
 	p->scx.slice = SCX_SLICE_DFL;
-	__scx_add_event(SCX_EV_ENQ_SLICE_DFL, 1);
+	__scx_add_event(SCX_EV_REFILL_SLICE_DFL, 1);
 local_norefill:
 	dispatch_enqueue(&rq->scx.local_dsq, p, enq_flags);
 	return;
@@ -2205,7 +2205,7 @@ static void do_enqueue_task(struct rq *rq, struct task_struct *p, u64 enq_flags,
 global:
 	touch_core_sched(rq, p);	/* see the comment in local: */
 	p->scx.slice = SCX_SLICE_DFL;
-	__scx_add_event(SCX_EV_ENQ_SLICE_DFL, 1);
+	__scx_add_event(SCX_EV_REFILL_SLICE_DFL, 1);
 	dispatch_enqueue(find_global_dsq(p), p, enq_flags);
 }
 
@@ -3296,7 +3296,7 @@ static struct task_struct *pick_task_scx(struct rq *rq)
 		p = prev;
 		if (!p->scx.slice) {
 			p->scx.slice = SCX_SLICE_DFL;
-			__scx_add_event(SCX_EV_ENQ_SLICE_DFL, 1);
+			__scx_add_event(SCX_EV_REFILL_SLICE_DFL, 1);
 		}
 	} else {
 		p = first_local_task(rq);
@@ -3313,7 +3313,7 @@ static struct task_struct *pick_task_scx(struct rq *rq)
 				scx_warned_zero_slice = true;
 			}
 			p->scx.slice = SCX_SLICE_DFL;
-			__scx_add_event(SCX_EV_ENQ_SLICE_DFL, 1);
+			__scx_add_event(SCX_EV_REFILL_SLICE_DFL, 1);
 		}
 	}
 
@@ -3399,7 +3399,7 @@ static int select_task_rq_scx(struct task_struct *p, int prev_cpu, int wake_flag
 		if (cpu >= 0) {
 			p->scx.slice = SCX_SLICE_DFL;
 			p->scx.ddsp_dsq_id = SCX_DSQ_LOCAL;
-			__scx_add_event(SCX_EV_ENQ_SLICE_DFL, 1);
+			__scx_add_event(SCX_EV_REFILL_SLICE_DFL, 1);
 		} else {
 			cpu = prev_cpu;
 		}
@@ -4413,7 +4413,7 @@ static ssize_t scx_attr_events_show(struct kobject *kobj,
 	at += scx_attr_event_show(buf, at, &events, SCX_EV_DISPATCH_KEEP_LAST);
 	at += scx_attr_event_show(buf, at, &events, SCX_EV_ENQ_SKIP_EXITING);
 	at += scx_attr_event_show(buf, at, &events, SCX_EV_ENQ_SKIP_MIGRATION_DISABLED);
-	at += scx_attr_event_show(buf, at, &events, SCX_EV_ENQ_SLICE_DFL);
+	at += scx_attr_event_show(buf, at, &events, SCX_EV_REFILL_SLICE_DFL);
 	at += scx_attr_event_show(buf, at, &events, SCX_EV_BYPASS_DURATION);
 	at += scx_attr_event_show(buf, at, &events, SCX_EV_BYPASS_DISPATCH);
 	at += scx_attr_event_show(buf, at, &events, SCX_EV_BYPASS_ACTIVATE);
@@ -5148,7 +5148,7 @@ static void scx_dump_state(struct scx_exit_info *ei, size_t dump_len)
 	scx_dump_event(s, &events, SCX_EV_DISPATCH_KEEP_LAST);
 	scx_dump_event(s, &events, SCX_EV_ENQ_SKIP_EXITING);
 	scx_dump_event(s, &events, SCX_EV_ENQ_SKIP_MIGRATION_DISABLED);
-	scx_dump_event(s, &events, SCX_EV_ENQ_SLICE_DFL);
+	scx_dump_event(s, &events, SCX_EV_REFILL_SLICE_DFL);
 	scx_dump_event(s, &events, SCX_EV_BYPASS_DURATION);
 	scx_dump_event(s, &events, SCX_EV_BYPASS_DISPATCH);
 	scx_dump_event(s, &events, SCX_EV_BYPASS_ACTIVATE);
@@ -7313,7 +7313,7 @@ __bpf_kfunc void scx_bpf_events(struct scx_event_stats *events,
 		scx_agg_event(&e_sys, e_cpu, SCX_EV_DISPATCH_KEEP_LAST);
 		scx_agg_event(&e_sys, e_cpu, SCX_EV_ENQ_SKIP_EXITING);
 		scx_agg_event(&e_sys, e_cpu, SCX_EV_ENQ_SKIP_MIGRATION_DISABLED);
-		scx_agg_event(&e_sys, e_cpu, SCX_EV_ENQ_SLICE_DFL);
+		scx_agg_event(&e_sys, e_cpu, SCX_EV_REFILL_SLICE_DFL);
 		scx_agg_event(&e_sys, e_cpu, SCX_EV_BYPASS_DURATION);
 		scx_agg_event(&e_sys, e_cpu, SCX_EV_BYPASS_DISPATCH);
 		scx_agg_event(&e_sys, e_cpu, SCX_EV_BYPASS_ACTIVATE);
diff --git a/tools/sched_ext/scx_qmap.bpf.c b/tools/sched_ext/scx_qmap.bpf.c
index 26c40ca4f36c..c3cd9a17d48e 100644
--- a/tools/sched_ext/scx_qmap.bpf.c
+++ b/tools/sched_ext/scx_qmap.bpf.c
@@ -784,8 +784,8 @@ static int monitor_timerfn(void *map, int *key, struct bpf_timer *timer)
 		   scx_read_event(&events, SCX_EV_DISPATCH_KEEP_LAST));
 	bpf_printk("%35s: %lld", "SCX_EV_ENQ_SKIP_EXITING",
 		   scx_read_event(&events, SCX_EV_ENQ_SKIP_EXITING));
-	bpf_printk("%35s: %lld", "SCX_EV_ENQ_SLICE_DFL",
-		   scx_read_event(&events, SCX_EV_ENQ_SLICE_DFL));
+	bpf_printk("%35s: %lld", "SCX_EV_REFILL_SLICE_DFL",
+		   scx_read_event(&events, SCX_EV_REFILL_SLICE_DFL));
 	bpf_printk("%35s: %lld", "SCX_EV_BYPASS_DURATION",
 		   scx_read_event(&events, SCX_EV_BYPASS_DURATION));
 	bpf_printk("%35s: %lld", "SCX_EV_BYPASS_DISPATCH",
-- 
2.45.2

[PATCH 2/2] sched_ext: add helper for refill task with default slice

[Honglei Wang]

Add helper for refilling task with default slice and event
statistics accordingly.

Signed-off-by: Honglei Wang <jameshongleiwang@126.com>
---
 kernel/sched/ext.c | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 594087ac4c9e..df7319bd9079 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -1815,6 +1815,12 @@ static void dsq_mod_nr(struct scx_dispatch_q *dsq, s32 delta)
 	WRITE_ONCE(dsq->nr, dsq->nr + delta);
 }
 
+static void refill_task_slice_dfl(struct task_struct *p)
+{
+	p->scx.slice = SCX_SLICE_DFL;
+	__scx_add_event(SCX_EV_REFILL_SLICE_DFL, 1);
+}
+
 static void dispatch_enqueue(struct scx_dispatch_q *dsq, struct task_struct *p,
 			     u64 enq_flags)
 {
@@ -2196,16 +2202,14 @@ static void do_enqueue_task(struct rq *rq, struct task_struct *p, u64 enq_flags,
 	 * higher priority it becomes from scx_prio_less()'s POV.
 	 */
 	touch_core_sched(rq, p);
-	p->scx.slice = SCX_SLICE_DFL;
-	__scx_add_event(SCX_EV_REFILL_SLICE_DFL, 1);
+	refill_task_slice_dfl(p);
 local_norefill:
 	dispatch_enqueue(&rq->scx.local_dsq, p, enq_flags);
 	return;
 
 global:
 	touch_core_sched(rq, p);	/* see the comment in local: */
-	p->scx.slice = SCX_SLICE_DFL;
-	__scx_add_event(SCX_EV_REFILL_SLICE_DFL, 1);
+	refill_task_slice_dfl(p);
 	dispatch_enqueue(find_global_dsq(p), p, enq_flags);
 }
 
@@ -3294,10 +3298,8 @@ static struct task_struct *pick_task_scx(struct rq *rq)
 	 */
 	if (keep_prev) {
 		p = prev;
-		if (!p->scx.slice) {
-			p->scx.slice = SCX_SLICE_DFL;
-			__scx_add_event(SCX_EV_REFILL_SLICE_DFL, 1);
-		}
+		if (!p->scx.slice)
+			refill_task_slice_dfl(p);
 	} else {
 		p = first_local_task(rq);
 		if (!p) {
@@ -3312,8 +3314,7 @@ static struct task_struct *pick_task_scx(struct rq *rq)
 						p->comm, p->pid, __func__);
 				scx_warned_zero_slice = true;
 			}
-			p->scx.slice = SCX_SLICE_DFL;
-			__scx_add_event(SCX_EV_REFILL_SLICE_DFL, 1);
+			refill_task_slice_dfl(p);
 		}
 	}
 
@@ -3397,9 +3398,8 @@ static int select_task_rq_scx(struct task_struct *p, int prev_cpu, int wake_flag
 
 		cpu = scx_select_cpu_dfl(p, prev_cpu, wake_flags, 0);
 		if (cpu >= 0) {
-			p->scx.slice = SCX_SLICE_DFL;
+			refill_task_slice_dfl(p);
 			p->scx.ddsp_dsq_id = SCX_DSQ_LOCAL;
-			__scx_add_event(SCX_EV_REFILL_SLICE_DFL, 1);
 		} else {
 			cpu = prev_cpu;
 		}
-- 
2.45.2

Re: [PATCH 0/2] rename var for slice refill event and add helper

[Tejun Heo]

On Thu, Apr 17, 2025 at 04:07:06PM +0800, Honglei Wang wrote:
> SCX_EV_ENQ_SLICE_DFL gives the impression that the event only occurs
> when the tasks were enqueued, which seems not accurate. So rename the
> variable to SCX_EV_REFILL_SLICE_DFL.
> 
> The slice refilling with default slice always come with event
> statistics together, add a helper routine to make it cleaner.
> 
> Honglei Wang (2):
>   sched_ext: change the variable name for slice refill event
>   sched_ext: add helper for refill task with default slice

They look fine to me. Changwoo?

Thanks.

-- 
tejun

Re: [PATCH 1/2] sched_ext: change the variable name for slice refill event

[Andrea Righi]

Hi Honglei,

On Thu, Apr 17, 2025 at 04:07:07PM +0800, Honglei Wang wrote:
> SCX_EV_ENQ_SLICE_DFL gives the impression that the event only occurs
> when the tasks were enqueued, which seems not accurate. What it actually
> means is the refilling with defalt slice, and this can occur either when
> enqueue or pick_task. Let's change the variable to
> SCX_EV_REFILL_SLICE_DFL.
> 
> Signed-off-by: Honglei Wang <jameshongleiwang@126.com>
> ---
>  kernel/sched/ext.c             | 22 +++++++++++-----------
>  tools/sched_ext/scx_qmap.bpf.c |  4 ++--
>  2 files changed, 13 insertions(+), 13 deletions(-)
> 
> diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
> index 66bcd40a28ca..594087ac4c9e 100644
> --- a/kernel/sched/ext.c
> +++ b/kernel/sched/ext.c
> @@ -1517,10 +1517,10 @@ struct scx_event_stats {
>  	s64		SCX_EV_ENQ_SKIP_MIGRATION_DISABLED;
>  
>  	/*
> -	 * The total number of tasks enqueued (or pick_task-ed) with a
> -	 * default time slice (SCX_SLICE_DFL).
> +	 * The total number of tasks slice refill with default time slice
> +	 * (SCX_SLICE_DFL).

Nit, how about:

Total number of times a task's time slice was refilled with the default
value (SCX_SLICE_DFL).

Thanks,
-Andrea

Re: [PATCH 1/2] sched_ext: change the variable name for slice refill event

[Honglei Wang]

Hi Andrea,

On 2025/4/18 02:30, Andrea Righi wrote:
> Hi Honglei,
> 
> On Thu, Apr 17, 2025 at 04:07:07PM +0800, Honglei Wang wrote:
>> SCX_EV_ENQ_SLICE_DFL gives the impression that the event only occurs
>> when the tasks were enqueued, which seems not accurate. What it actually
>> means is the refilling with defalt slice, and this can occur either when
>> enqueue or pick_task. Let's change the variable to
>> SCX_EV_REFILL_SLICE_DFL.
>>
>> Signed-off-by: Honglei Wang <jameshongleiwang@126.com>
>> ---
>>  kernel/sched/ext.c             | 22 +++++++++++-----------
>>  tools/sched_ext/scx_qmap.bpf.c |  4 ++--
>>  2 files changed, 13 insertions(+), 13 deletions(-)
>>
>> diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
>> index 66bcd40a28ca..594087ac4c9e 100644
>> --- a/kernel/sched/ext.c
>> +++ b/kernel/sched/ext.c
>> @@ -1517,10 +1517,10 @@ struct scx_event_stats {
>>  	s64		SCX_EV_ENQ_SKIP_MIGRATION_DISABLED;
>>  
>>  	/*
>> -	 * The total number of tasks enqueued (or pick_task-ed) with a
>> -	 * default time slice (SCX_SLICE_DFL).
>> +	 * The total number of tasks slice refill with default time slice
>> +	 * (SCX_SLICE_DFL).
> 
> Nit, how about:
> 
> Total number of times a task's time slice was refilled with the default
> value (SCX_SLICE_DFL).
> 

OK, will send a update later.

Thanks,
Honglei

> Thanks,
> -Andrea