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The lack of a dedicated reason > makes debugging and observability more difficult. > > Add SCX_CPU_PREEMPT_FAIR and report it when the next scheduled > task belongs to fair_sched_class. > > This change improves scheduling diagnostics and observability > without affecting scheduling behavior. The preempt reason is only used in ops.cpu_release(), which is a deprecated API and will be removed in the next kernel versions (see the pr_warn() in validate_ops(), kernel/sched/ext.c): pr_warn("ops->cpu_acquire/release() are deprecated, use sched_switch TP instead\n"); So, your patch makes sense, but I'm not sure it's worth updating the API at this point. Thanks, -Andrea > > Signed-off-by: Cui Jian > --- > kernel/sched/ext.c | 2 ++ > kernel/sched/ext_internal.h | 2 ++ > 2 files changed, 4 insertions(+) > > diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c > index 5d2d19473a82..6e0281218197 100644 > --- a/kernel/sched/ext.c > +++ b/kernel/sched/ext.c > @@ -3015,6 +3015,8 @@ preempt_reason_from_class(const struct sched_class *class) > return SCX_CPU_PREEMPT_DL; > if (class == &rt_sched_class) > return SCX_CPU_PREEMPT_RT; > + if (class == &fair_sched_class) > + return SCX_CPU_PREEMPT_FAIR; > return SCX_CPU_PREEMPT_UNKNOWN; > } > > diff --git a/kernel/sched/ext_internal.h b/kernel/sched/ext_internal.h > index a075732d4430..3ce07bec58a5 100644 > --- a/kernel/sched/ext_internal.h > +++ b/kernel/sched/ext_internal.h > @@ -241,6 +241,8 @@ enum scx_cpu_preempt_reason { > SCX_CPU_PREEMPT_DL, > /* next task is being scheduled by &sched_class_stop */ > SCX_CPU_PREEMPT_STOP, > + /* next task is being scheduled by &sched_class_fair*/ > + SCX_CPU_PREEMPT_FAIR, > /* unknown reason for SCX being preempted */ > SCX_CPU_PREEMPT_UNKNOWN, > }; > -- > 2.34.1 >