1 files changed, 23 insertions, 34 deletions

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index 5a9a4b81c972..e41a36bd66a6 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -489,13 +489,6 @@ static inline int is_leftmost(struct task_struct *p, struct dl_rq *dl_rq)
 
 static void init_dl_rq_bw_ratio(struct dl_rq *dl_rq);
 
-void init_dl_bandwidth(struct dl_bandwidth *dl_b, u64 period, u64 runtime)
-{
-	raw_spin_lock_init(&dl_b->dl_runtime_lock);
-	dl_b->dl_period = period;
-	dl_b->dl_runtime = runtime;
-}
-
 void init_dl_bw(struct dl_bw *dl_b)
 {
 	raw_spin_lock_init(&dl_b->lock);
@@ -1260,43 +1253,39 @@ int dl_runtime_exceeded(struct sched_dl_entity *dl_se)
 }
 
 /*
- * This function implements the GRUB accounting rule:
- * according to the GRUB reclaiming algorithm, the runtime is
- * not decreased as "dq = -dt", but as
- * "dq = -max{u / Umax, (1 - Uinact - Uextra)} dt",
+ * This function implements the GRUB accounting rule. According to the
+ * GRUB reclaiming algorithm, the runtime is not decreased as "dq = -dt",
+ * but as "dq = -(max{u, (Umax - Uinact - Uextra)} / Umax) dt",
  * where u is the utilization of the task, Umax is the maximum reclaimable
  * utilization, Uinact is the (per-runqueue) inactive utilization, computed
  * as the difference between the "total runqueue utilization" and the
- * runqueue active utilization, and Uextra is the (per runqueue) extra
+ * "runqueue active utilization", and Uextra is the (per runqueue) extra
  * reclaimable utilization.
- * Since rq->dl.running_bw and rq->dl.this_bw contain utilizations
- * multiplied by 2^BW_SHIFT, the result has to be shifted right by
- * BW_SHIFT.
- * Since rq->dl.bw_ratio contains 1 / Umax multiplied by 2^RATIO_SHIFT,
- * dl_bw is multiped by rq->dl.bw_ratio and shifted right by RATIO_SHIFT.
- * Since delta is a 64 bit variable, to have an overflow its value
- * should be larger than 2^(64 - 20 - 8), which is more than 64 seconds.
- * So, overflow is not an issue here.
+ * Since rq->dl.running_bw and rq->dl.this_bw contain utilizations multiplied
+ * by 2^BW_SHIFT, the result has to be shifted right by BW_SHIFT.
+ * Since rq->dl.bw_ratio contains 1 / Umax multiplied by 2^RATIO_SHIFT, dl_bw
+ * is multiped by rq->dl.bw_ratio and shifted right by RATIO_SHIFT.
+ * Since delta is a 64 bit variable, to have an overflow its value should be
+ * larger than 2^(64 - 20 - 8), which is more than 64 seconds. So, overflow is
+ * not an issue here.
  */
 static u64 grub_reclaim(u64 delta, struct rq *rq, struct sched_dl_entity *dl_se)
 {
-	u64 u_inact = rq->dl.this_bw - rq->dl.running_bw; /* Utot - Uact */
 	u64 u_act;
-	u64 u_act_min = (dl_se->dl_bw * rq->dl.bw_ratio) >> RATIO_SHIFT;
+	u64 u_inact = rq->dl.this_bw - rq->dl.running_bw; /* Utot - Uact */
 
 	/*
-	 * Instead of computing max{u * bw_ratio, (1 - u_inact - u_extra)},
-	 * we compare u_inact + rq->dl.extra_bw with
-	 * 1 - (u * rq->dl.bw_ratio >> RATIO_SHIFT), because
-	 * u_inact + rq->dl.extra_bw can be larger than
-	 * 1 * (so, 1 - u_inact - rq->dl.extra_bw would be negative
-	 * leading to wrong results)
+	 * Instead of computing max{u, (u_max - u_inact - u_extra)}, we
+	 * compare u_inact + u_extra with u_max - u, because u_inact + u_extra
+	 * can be larger than u_max. So, u_max - u_inact - u_extra would be
+	 * negative leading to wrong results.
 	 */
-	if (u_inact + rq->dl.extra_bw > BW_UNIT - u_act_min)
-		u_act = u_act_min;
+	if (u_inact + rq->dl.extra_bw > rq->dl.max_bw - dl_se->dl_bw)
+		u_act = dl_se->dl_bw;
 	else
-		u_act = BW_UNIT - u_inact - rq->dl.extra_bw;
+		u_act = rq->dl.max_bw - u_inact - rq->dl.extra_bw;
 
+	u_act = (u_act * rq->dl.bw_ratio) >> RATIO_SHIFT;
 	return (delta * u_act) >> BW_SHIFT;
 }
 
@@ -2795,12 +2784,12 @@ static void init_dl_rq_bw_ratio(struct dl_rq *dl_rq)
 {
 	if (global_rt_runtime() == RUNTIME_INF) {
 		dl_rq->bw_ratio = 1 << RATIO_SHIFT;
-		dl_rq->extra_bw = 1 << BW_SHIFT;
+		dl_rq->max_bw = dl_rq->extra_bw = 1 << BW_SHIFT;
 	} else {
 		dl_rq->bw_ratio = to_ratio(global_rt_runtime(),
 			  global_rt_period()) >> (BW_SHIFT - RATIO_SHIFT);
-		dl_rq->extra_bw = to_ratio(global_rt_period(),
-						    global_rt_runtime());
+		dl_rq->max_bw = dl_rq->extra_bw =
+			to_ratio(global_rt_period(), global_rt_runtime());
 	}
 }