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

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Message-Id: <20230322151843.14390-2-lukasz.luba@arm.com>
Date:   Wed, 22 Mar 2023 15:18:41 +0000
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
Subject: [PATCH 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 488655f2319f..882c92e3ccf0 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -110,6 +110,7 @@ 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);
 
@@ -1936,12 +1937,16 @@ 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);
 	}
 }
 
-- 
2.17.1