* [PATCH v2] sched_ext: switch class when preempted by higher priority scheduler
@ 2025-01-08 2:33 Honglei Wang
2025-01-08 9:05 ` Andrea Righi
2025-01-08 16:46 ` Tejun Heo
0 siblings, 2 replies; 4+ messages in thread
From: Honglei Wang @ 2025-01-08 2:33 UTC (permalink / raw)
To: tj, void, arighi, changwoo
Cc: mingo, peterz, juri.lelli, vincent.guittot, dietmar.eggemann,
rostedt, bsegall, mgorman, vschneid, linux-kernel
ops.cpu_release() function, if defined, must be invoked when preempted by
a higher priority scheduler class task. This scenario was skipped in
commit f422316d7466 ("sched_ext: Remove switch_class_scx()"). Let's fix
it.
Fixes: f422316d7466 ("sched_ext: Remove switch_class_scx()")
Signed-off-by: Honglei Wang <jameshongleiwang@126.com>
---
kernel/sched/ext.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 19d2699cf638..ef0e3f2c1e6f 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -3034,7 +3034,7 @@ static void put_prev_task_scx(struct rq *rq, struct task_struct *p,
*/
if (p->scx.slice && !scx_rq_bypassing(rq)) {
dispatch_enqueue(&rq->scx.local_dsq, p, SCX_ENQ_HEAD);
- return;
+ goto switch_class;
}
/*
@@ -3051,6 +3051,7 @@ static void put_prev_task_scx(struct rq *rq, struct task_struct *p,
}
}
+switch_class:
if (next && next->sched_class != &ext_sched_class)
switch_class(rq, next);
}
--
2.45.2
^ permalink raw reply related [flat|nested] 4+ messages in thread* Re: [PATCH v2] sched_ext: switch class when preempted by higher priority scheduler
2025-01-08 2:33 [PATCH v2] sched_ext: switch class when preempted by higher priority scheduler Honglei Wang
@ 2025-01-08 9:05 ` Andrea Righi
2025-01-08 11:00 ` Honglei Wang
2025-01-08 16:46 ` Tejun Heo
1 sibling, 1 reply; 4+ messages in thread
From: Andrea Righi @ 2025-01-08 9:05 UTC (permalink / raw)
To: Honglei Wang
Cc: tj, void, changwoo, mingo, peterz, juri.lelli, vincent.guittot,
dietmar.eggemann, rostedt, bsegall, mgorman, vschneid,
linux-kernel
Hi Honglei,
On Wed, Jan 08, 2025 at 10:33:28AM +0800, Honglei Wang wrote:
> ops.cpu_release() function, if defined, must be invoked when preempted by
> a higher priority scheduler class task. This scenario was skipped in
> commit f422316d7466 ("sched_ext: Remove switch_class_scx()"). Let's fix
> it.
>
> Fixes: f422316d7466 ("sched_ext: Remove switch_class_scx()")
> Signed-off-by: Honglei Wang <jameshongleiwang@126.com>
Thanks a lot for catching this, I've also reproduced a stall (due to the
missing ops.cpu_release() invocation) and verified that your fixes resolve
the problem, so:
Acked-by: Andrea Righi <arighi@nvidia.com>
> ---
> kernel/sched/ext.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
> index 19d2699cf638..ef0e3f2c1e6f 100644
> --- a/kernel/sched/ext.c
> +++ b/kernel/sched/ext.c
> @@ -3034,7 +3034,7 @@ static void put_prev_task_scx(struct rq *rq, struct task_struct *p,
> */
> if (p->scx.slice && !scx_rq_bypassing(rq)) {
> dispatch_enqueue(&rq->scx.local_dsq, p, SCX_ENQ_HEAD);
> - return;
> + goto switch_class;
> }
>
> /*
> @@ -3051,6 +3051,7 @@ static void put_prev_task_scx(struct rq *rq, struct task_struct *p,
> }
> }
>
> +switch_class:
> if (next && next->sched_class != &ext_sched_class)
> switch_class(rq, next);
> }
> --
> 2.45.2
>
-Andrea
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH v2] sched_ext: switch class when preempted by higher priority scheduler
2025-01-08 9:05 ` Andrea Righi
@ 2025-01-08 11:00 ` Honglei Wang
0 siblings, 0 replies; 4+ messages in thread
From: Honglei Wang @ 2025-01-08 11:00 UTC (permalink / raw)
To: Andrea Righi
Cc: tj, void, changwoo, mingo, peterz, juri.lelli, vincent.guittot,
dietmar.eggemann, rostedt, bsegall, mgorman, vschneid,
linux-kernel
On 2025/1/8 17:05, Andrea Righi wrote:
> Hi Honglei,
>
> On Wed, Jan 08, 2025 at 10:33:28AM +0800, Honglei Wang wrote:
>> ops.cpu_release() function, if defined, must be invoked when preempted by
>> a higher priority scheduler class task. This scenario was skipped in
>> commit f422316d7466 ("sched_ext: Remove switch_class_scx()"). Let's fix
>> it.
>>
>> Fixes: f422316d7466 ("sched_ext: Remove switch_class_scx()")
>> Signed-off-by: Honglei Wang <jameshongleiwang@126.com>
>
> Thanks a lot for catching this, I've also reproduced a stall (due to the
> missing ops.cpu_release() invocation) and verified that your fixes resolve
> the problem, so:
>
> Acked-by: Andrea Righi <arighi@nvidia.com>
>
Thanks a lot for looking at the code and the test, Andrea.
>> ---
>> kernel/sched/ext.c | 3 ++-
>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
>> index 19d2699cf638..ef0e3f2c1e6f 100644
>> --- a/kernel/sched/ext.c
>> +++ b/kernel/sched/ext.c
>> @@ -3034,7 +3034,7 @@ static void put_prev_task_scx(struct rq *rq, struct task_struct *p,
>> */
>> if (p->scx.slice && !scx_rq_bypassing(rq)) {
>> dispatch_enqueue(&rq->scx.local_dsq, p, SCX_ENQ_HEAD);
>> - return;
>> + goto switch_class;
>> }
>>
>> /*
>> @@ -3051,6 +3051,7 @@ static void put_prev_task_scx(struct rq *rq, struct task_struct *p,
>> }
>> }
>>
>> +switch_class:
>> if (next && next->sched_class != &ext_sched_class)
>> switch_class(rq, next);
>> }
>> --
>> 2.45.2
>>
>
> -Andrea
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v2] sched_ext: switch class when preempted by higher priority scheduler
2025-01-08 2:33 [PATCH v2] sched_ext: switch class when preempted by higher priority scheduler Honglei Wang
2025-01-08 9:05 ` Andrea Righi
@ 2025-01-08 16:46 ` Tejun Heo
1 sibling, 0 replies; 4+ messages in thread
From: Tejun Heo @ 2025-01-08 16:46 UTC (permalink / raw)
To: Honglei Wang
Cc: void, arighi, changwoo, mingo, peterz, juri.lelli,
vincent.guittot, dietmar.eggemann, rostedt, bsegall, mgorman,
vschneid, linux-kernel
On Wed, Jan 08, 2025 at 10:33:28AM +0800, Honglei Wang wrote:
> ops.cpu_release() function, if defined, must be invoked when preempted by
> a higher priority scheduler class task. This scenario was skipped in
> commit f422316d7466 ("sched_ext: Remove switch_class_scx()"). Let's fix
> it.
>
> Fixes: f422316d7466 ("sched_ext: Remove switch_class_scx()")
> Signed-off-by: Honglei Wang <jameshongleiwang@126.com>
Applied to sched_ext/for-6.13-fixes.
Thanks.
--
tejun
^ permalink raw reply [flat|nested] 4+ messages in thread
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2025-01-08 2:33 [PATCH v2] sched_ext: switch class when preempted by higher priority scheduler Honglei Wang
2025-01-08 9:05 ` Andrea Righi
2025-01-08 11:00 ` Honglei Wang
2025-01-08 16:46 ` Tejun Heo
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