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 | 15 +++++++++++++++
2 files changed, 33 insertions(+)
diff --git a/include/linux/sched/ext.h b/include/linux/sched/ext.h
index 82ead36d1136..01c846445243 100644
--- a/include/linux/sched/ext.h
+++ b/include/linux/sched/ext.h
@@ -368,6 +368,24 @@ 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 072082968f0f..e981b7111e0a 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -1727,6 +1727,18 @@ void __scx_update_idle(struct rq *rq, bool idle)
}
}
+static void rq_online_scx(struct rq *rq, enum rq_onoff_reason reason)
+{
+ if (SCX_HAS_OP(cpu_online) && reason == RQ_ONOFF_HOTPLUG)
+ scx_ops.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_ops.cpu_offline(cpu_of(rq));
+}
+
#else /* !CONFIG_SMP */
static bool test_and_clear_cpu_idle(int cpu) { return false; }
@@ -2215,6 +2227,9 @@ 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,
--
2.39.1
