linux-kernel - [PATCH v2 2/3] sched/deadline: Throttle the task when missing its deadline

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Date:   Fri, 12 May 2017 11:32:08 +0800
From:   Xunlei Pang <xlpang@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Juri Lelli <juri.lelli@....com>,
        Ingo Molnar <mingo@...hat.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Luca Abeni <luca.abeni@...tannapisa.it>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Xunlei Pang <xlpang@...hat.com>,
        Luca Abeni <luca.abeni@...tn.it>
Subject: [PATCH v2 2/3] sched/deadline: Throttle the task when missing its deadline

dl_runtime_exceeded() only checks negative runtime, actually
when the current deadline past, we should start a new period
and zero out the remaining runtime as well.

This patch improves dl_runtime_exceeded() to achieve that.

Fixes: 269ad8015a6b ("sched/deadline: Avoid double-accounting in case of missed deadlines")
Cc: Luca Abeni <luca.abeni@...tn.it>
Signed-off-by: Xunlei Pang <xlpang@...hat.com>
---
 kernel/sched/deadline.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index d3d291e..5691149 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -729,8 +729,13 @@ static inline void dl_check_constrained_dl(struct sched_dl_entity *dl_se)
 }
 
 static
-int dl_runtime_exceeded(struct sched_dl_entity *dl_se)
+int dl_runtime_exceeded(struct rq *rq, struct sched_dl_entity *dl_se)
 {
+	bool dmiss = dl_time_before(dl_se->deadline, rq_clock(rq));
+
+	if (dmiss && dl_se->runtime > 0)
+		dl_se->runtime = 0;
+
 	return (dl_se->runtime <= 0);
 }
 
@@ -781,7 +786,7 @@ static void update_curr_dl(struct rq *rq)
 	dl_se->runtime -= delta_exec;
 
 throttle:
-	if (dl_runtime_exceeded(dl_se) || dl_se->dl_yielded) {
+	if (dl_runtime_exceeded(rq, dl_se) || dl_se->dl_yielded) {
 		dl_se->dl_throttled = 1;
 		__dequeue_task_dl(rq, curr, 0);
 		if (unlikely(dl_se->dl_boosted || !start_dl_timer(curr)))
-- 
1.8.3.1