[RFC PATCH v2 08/25] sched/deadline: Account rt-cgroups bandwidth in deadline tasks schedulability tests.

[Yuri Andriaccio]

From: luca abeni <luca.abeni@xxxxxxxxxxxxxxx>

Account the rt-cgroups hierarchy's reserved bandwidth in the schedulability
test of deadline entities. This mechanism allows to completely reserve portion
of the rt-bandwidth to rt-cgroups even if they do not use all of it.

Co-developed-by: Alessio Balsini <a.balsini@xxxxxxxx>
Signed-off-by: Alessio Balsini <a.balsini@xxxxxxxx>
Co-developed-by: Andrea Parri <parri.andrea@xxxxxxxxx>
Signed-off-by: Andrea Parri <parri.andrea@xxxxxxxxx>
Co-developed-by: Yuri Andriaccio <yurand2000@xxxxxxxxx>
Signed-off-by: Yuri Andriaccio <yurand2000@xxxxxxxxx>
Signed-off-by: luca abeni <luca.abeni@xxxxxxxxxxxxxxx>
---
 kernel/sched/deadline.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 0640d0ca45b..43af48038b9 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -231,8 +231,15 @@ void __dl_add(struct dl_bw *dl_b, u64 tsk_bw, int cpus)
 static inline bool
 __dl_overflow(struct dl_bw *dl_b, unsigned long cap, u64 old_bw, u64 new_bw)
 {
+	u64 dl_groups_root = 0;
+
+#ifdef CONFIG_RT_GROUP_SCHED
+	dl_groups_root = to_ratio(root_task_group.dl_bandwidth.dl_period,
+				  root_task_group.dl_bandwidth.dl_runtime);
+#endif
 	return dl_b->bw != -1 &&
-	       cap_scale(dl_b->bw, cap) < dl_b->total_bw - old_bw + new_bw;
+	       cap_scale(dl_b->bw, cap) < dl_b->total_bw - old_bw + new_bw
+					+ cap_scale(dl_groups_root, cap);
 }
 
 static inline
-- 
2.50.1