[PATCH v4 14/15] Remove the ext server BW before changing tasks to FAIR

From: Joel Fernandes
Date: Tue Jun 17 2025 - 16:08:54 EST


Signed-off-by: Joel Fernandes <joelagnelf@xxxxxxxxxx>
---
kernel/sched/ext.c | 39 +++++++++++++++++++++++++--------------
1 file changed, 25 insertions(+), 14 deletions(-)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index 84ccab8cb838..23e5711bc4fc 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -4960,6 +4960,31 @@ static void scx_disable_workfn(struct kthread_work *work)

scx_init_task_enabled = false;

+ for_each_possible_cpu(cpu) {
+ struct rq *rq = cpu_rq(cpu);
+ struct rq_flags rf;
+
+ /*
+ * Invalidate all the rq clocks to prevent getting outdated
+ * rq clocks from a previous scx scheduler.
+ */
+ scx_rq_clock_invalidate(rq);
+
+ /*
+ * We are unloading the sched_ext scheduler, we do not need its
+ * DL server bandwidth anymore, remove it for all CPUs. Whenever
+ * the first SCX task is enqueued (when scx is re-loaded), its DL
+ * server bandwidth will be re-initialized.
+ */
+ rq_lock_irqsave(rq, &rf);
+ update_rq_clock(rq);
+ if (dl_server_active(&rq->ext_server))
+ dl_server_stop(&rq->ext_server);
+ dl_server_remove_params(&rq->ext_server);
+ rq_unlock_irqrestore(rq, &rf);
+ }
+
+
scx_task_iter_start(&sti);
while ((p = scx_task_iter_next_locked(&sti))) {
const struct sched_class *old_class = p->sched_class;
@@ -4985,26 +5010,12 @@ static void scx_disable_workfn(struct kthread_work *work)

for_each_possible_cpu(cpu) {
struct rq *rq = cpu_rq(cpu);
- struct rq_flags rf;

/*
* Invalidate all the rq clocks to prevent getting outdated
* rq clocks from a previous scx scheduler.
*/
scx_rq_clock_invalidate(rq);
-
- /*
- * We are unloading the sched_ext scheduler, we do not need its
- * DL server bandwidth anymore, remove it for all CPUs. Whenever
- * the first SCX task is enqueued (when scx is re-loaded), its DL
- * server bandwidth will be re-initialized.
- */
- rq_lock_irqsave(rq, &rf);
- update_rq_clock(rq);
- if (dl_server_active(&rq->ext_server))
- dl_server_stop(&rq->ext_server);
- dl_server_remove_params(&rq->ext_server);
- rq_unlock_irqrestore(rq, &rf);
}

/* no task is on scx, turn off all the switches and flush in-progress calls */
--
2.43.0