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From: Atul Pant <quic_atulpant@quicinc.com>
To: mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com,
        vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
        rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de,
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        daniel.lezcano@linaro.org
Cc: Atul Pant <quic_atulpant@quicinc.com>, kernel@quicinc.com,
        linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org
Subject: [RFC PATCH 1/2] sched/rt: Disable runtime accounting for idle threads with SCHED_FIFO policy
Date: Wed, 10 Apr 2024 10:24:16 +0530
Message-Id: <20240410045417.3048209-2-quic_atulpant@quicinc.com>
In-Reply-To: <20240410045417.3048209-1-quic_atulpant@quicinc.com>
References: <20240410045417.3048209-1-quic_atulpant@quicinc.com>
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To prevent the throttling of RT idle threads, like the idle-inject
threads, skip accounting of runtime for these threads.

Signed-off-by: Atul Pant <quic_atulpant@quicinc.com>
---
 kernel/sched/rt.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 4ac36eb4cdee..d20999270e75 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1075,7 +1075,9 @@ static void update_curr_rt(struct rq *rq)
 		struct rt_rq *rt_rq = rt_rq_of_se(rt_se);
 		int exceeded;
 
-		if (sched_rt_runtime(rt_rq) != RUNTIME_INF) {
+		if (sched_rt_runtime(rt_rq) != RUNTIME_INF &&
+				!(curr->policy == SCHED_FIFO &&
+					curr->flags & PF_IDLE)) {
 			raw_spin_lock(&rt_rq->rt_runtime_lock);
 			rt_rq->rt_time += delta_exec;
 			exceeded = sched_rt_runtime_exceeded(rt_rq);
-- 
2.25.1