Add ops.cpu_online/offline() which are invoked when CPUs come online and
offline respectively. As the enqueue path already automatically bypasses
tasks to the local dsq on a deactivated CPU, BPF schedulers are guaranteed
to see tasks only on CPUs which are between online() and offline().
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Reviewed-by: David Vernet <dvernet@xxxxxxxx>
Acked-by: Josh Don <joshdon@xxxxxxxxxx>
Acked-by: Hao Luo <haoluo@xxxxxxxxxx>
Acked-by: Barret Rhoden <brho@xxxxxxxxxx>
---
include/linux/sched/ext.h | 18 ++++++++++++++++++
kernel/sched/ext.c | 18 +++++++++++++++++-
2 files changed, 35 insertions(+), 1 deletion(-)
diff --git a/include/linux/sched/ext.h b/include/linux/sched/ext.h
index 633a2b550d0c..98b0f20a7c1d 100644
--- a/include/linux/sched/ext.h
+++ b/include/linux/sched/ext.h
@@ -378,6 +378,24 @@ struct sched_ext_ops {
*/
void (*cpu_release)(s32 cpu, struct scx_cpu_release_args *args);
+ /**
+ * cpu_online - A CPU became online
+ * @cpu: CPU which just came up
+ *
+ * @cpu just came online. @cpu doesn't call ops.enqueue() or run tasks
+ * associated with other CPUs beforehand.
+ */
+ void (*cpu_online)(s32 cpu);
+
+ /**
+ * cpu_offline - A CPU is going offline
+ * @cpu: CPU which is going offline
+ *
+ * @cpu is going offline. @cpu doesn't call ops.enqueue() or run tasks
+ * associated with other CPUs afterwards.
+ */
+ void (*cpu_offline)(s32 cpu);
+
/**
* prep_enable - Prepare to enable BPF scheduling for a task
* @p: task to prepare BPF scheduling for
diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 4e00a7cd660e..51078fab6df3 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -1404,7 +1404,8 @@ static int balance_scx(struct rq *rq, struct task_struct *prev,
* emitted in scx_notify_pick_next_task().
*/
if (SCX_HAS_OP(cpu_acquire))
- SCX_CALL_OP(0, cpu_acquire, cpu_of(rq), NULL);
+ SCX_CALL_OP(SCX_KF_UNLOCKED, cpu_acquire, cpu_of(rq),
+ NULL);
rq->scx.cpu_released = false;
}
@@ -1864,6 +1865,18 @@ void __scx_update_idle(struct rq *rq, bool idle)
#endif
}
+static void rq_online_scx(struct rq *rq, enum rq_onoff_reason reason)
+{
+ if (SCX_HAS_OP(cpu_online) && reason == RQ_ONOFF_HOTPLUG)
+ SCX_CALL_OP(SCX_KF_REST, cpu_online, cpu_of(rq));
+}
+
+static void rq_offline_scx(struct rq *rq, enum rq_onoff_reason reason)
+{
+ if (SCX_HAS_OP(cpu_offline) && reason == RQ_ONOFF_HOTPLUG)
+ SCX_CALL_OP(SCX_KF_REST, cpu_offline, cpu_of(rq));
+}
+
#else /* !CONFIG_SMP */
static bool test_and_clear_cpu_idle(int cpu) { return false; }
@@ -2381,6 +2394,9 @@ DEFINE_SCHED_CLASS(ext) = {
.balance = balance_scx,
.select_task_rq = select_task_rq_scx,
.set_cpus_allowed = set_cpus_allowed_scx,
+
+ .rq_online = rq_online_scx,
+ .rq_offline = rq_offline_scx,
#endif
.task_tick = task_tick_scx,
--
2.42.0
