linux-kernel - [PATCH v2 1/3] sched/tp: Add new tracepoint to track uclamp set from user-space

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Date:   Tue,  9 May 2023 13:22:44 +0100
From:   Lukasz Luba <lukasz.luba@....com>
To:     linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org
Cc:     rostedt@...dmis.org, mhiramat@...nel.org, mingo@...hat.com,
        peterz@...radead.org, juri.lelli@...hat.com,
        vincent.guittot@...aro.org, dietmar.eggemann@....com,
        bsegall@...gle.com, mgorman@...e.de, bristot@...hat.com,
        vschneid@...hat.com, delyank@...com, lukasz.luba@....com,
        qyousef@...gle.com, qyousef@...alina.io
Subject: [PATCH v2 1/3] sched/tp: Add new tracepoint to track uclamp set from user-space

The user-space can set uclamp value for a given task. It impacts task
placement decisions made by the scheduler. This is very useful information
and helps to understand the system behavior or track improvements in
middleware and applications which start using uclamp mechanisms and report
better performance in tests.

Signed-off-by: Lukasz Luba <lukasz.luba@....com>
---
 include/trace/events/sched.h | 4 ++++
 kernel/sched/core.c          | 5 +++++
 2 files changed, 9 insertions(+)

diff --git a/include/trace/events/sched.h b/include/trace/events/sched.h
index fbb99a61f714..dbfb30809f15 100644
--- a/include/trace/events/sched.h
+++ b/include/trace/events/sched.h
@@ -735,6 +735,10 @@ DECLARE_TRACE(sched_update_nr_running_tp,
 	TP_PROTO(struct rq *rq, int change),
 	TP_ARGS(rq, change));
 
+DECLARE_TRACE(uclamp_update_tsk_tp,
+	TP_PROTO(struct task_struct *tsk, int uclamp_id,  unsigned int value),
+	TP_ARGS(tsk, uclamp_id, value));
+
 #endif /* _TRACE_SCHED_H */
 
 /* This part must be outside protection */
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 944c3ae39861..7b9b800ebb6c 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -114,6 +114,7 @@ EXPORT_TRACEPOINT_SYMBOL_GPL(sched_overutilized_tp);
 EXPORT_TRACEPOINT_SYMBOL_GPL(sched_util_est_cfs_tp);
 EXPORT_TRACEPOINT_SYMBOL_GPL(sched_util_est_se_tp);
 EXPORT_TRACEPOINT_SYMBOL_GPL(sched_update_nr_running_tp);
+EXPORT_TRACEPOINT_SYMBOL_GPL(uclamp_update_tsk_tp);
 
 DEFINE_PER_CPU_SHARED_ALIGNED(struct rq, runqueues);
 
@@ -1956,12 +1957,16 @@ static void __setscheduler_uclamp(struct task_struct *p,
 	    attr->sched_util_min != -1) {
 		uclamp_se_set(&p->uclamp_req[UCLAMP_MIN],
 			      attr->sched_util_min, true);
+		trace_uclamp_update_tsk_tp(p, UCLAMP_MIN,
+					   attr->sched_util_min);
 	}
 
 	if (attr->sched_flags & SCHED_FLAG_UTIL_CLAMP_MAX &&
 	    attr->sched_util_max != -1) {
 		uclamp_se_set(&p->uclamp_req[UCLAMP_MAX],
 			      attr->sched_util_max, true);
+		trace_uclamp_update_tsk_tp(p, UCLAMP_MAX,
+					   attr->sched_util_max);
 	}
 }
 
-- 
2.25.1