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Date: Mon, 14 Apr 2025 19:48:41 +0800 Message-ID: <20250414114841.2181865-1-xieliujie@xiaomi.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: LiuJie Xie With __update_stats_wait_start() and __update_stats_wait_end(), we track task's latency and the info can be seen in proc node '/proc/pid/sched'. But it seems that we loss updating wait_time when rt task doing migration. In update_stats_dequeue_fair() by calling update_stats_wait_end_fair(), the fair sched class make this update work. When a rt doing migration, we can see: step1: wait_start=3D1503718063442 C:(__update_stats_wait_start<-ttwu_do_act= ivate<-try_to_wake_up) step2: wait_start=3D124844 C:(__update_stats_wait_start<-activate_task<-pus= h_rt_task<-push_rt_tasks<-finish_task_switch) step3: wait_start=3D124844 delta=3D1503718120473 C:(__update_stats_wait_end= <-__schedule<-schedule) In step2, the wait_start become very small after doing the below logic and we will get a very big delta in step3. void __update_stats_wait_start() { prev_wait_start =3D schedstat_val(stats->wait_start); if (p && likely(wait_start > prev_wait_start)) wait_start -=3D prev_wait_start; __schedstat_set(stats->wait_start, wait_start); } So, update_stats_dequeue_rt() should also update wait_time just like fair to get the correct delta. Signed-off-by: LiuJie Xie --- kernel/sched/rt.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index fa03ec3ed56a..a93d23b839ad 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -1346,6 +1346,13 @@ update_stats_dequeue_rt(struct rt_rq *rt_rq, struct = sched_rt_entity *rt_se, if (rt_entity_is_task(rt_se)) p =3D rt_task_of(rt_se); =20 + /* + * Mark the end of the wait period if dequeueing a + * waiting task: + */ + if (p && !task_on_cpu(task_rq(p), p)) + update_stats_wait_end_rt(rt_rq, rt_se); + if ((flags & DEQUEUE_SLEEP) && p) { unsigned int state; =20 --=20 2.43.0