linux-kernel - [PATCH 3/3] PM / devfreq: Add tracepoint for frequency changes

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Message-Id: <20201008075403.26181-4-cw00.choi@samsung.com>
Date:   Thu,  8 Oct 2020 16:54:03 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     mka@...omium.org, rostedt@...dmis.org, mingo@...hat.com,
        cw00.choi@...sung.com, chanwoo@...nel.org,
        myungjoo.ham@...sung.com, kyungmin.park@...sung.com
Subject: [PATCH 3/3] PM / devfreq: Add tracepoint for frequency changes

From: Matthias Kaehlcke <mka@...omium.org>

Add a tracepoint for frequency changes of devfreq devices and
use it.

Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
[cw00.choi: Move print position of tracepoint and add more information]
Signed-off-by: Chanwoo Choi <cw00.choi@...sung.com>
---
 drivers/devfreq/devfreq.c      |  8 ++++++++
 include/trace/events/devfreq.h | 28 ++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)

diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
index 5b069a8a1026..d4c4aa050efa 100644
--- a/drivers/devfreq/devfreq.c
+++ b/drivers/devfreq/devfreq.c
@@ -369,6 +369,14 @@ static int devfreq_set_target(struct devfreq *devfreq, unsigned long new_freq,
 		return err;
 	}
 
+	/*
+	 * Print devfreq_frequency trace information between DEVFREQ_PRECHANGE
+	 * and DEVFREQ_POSTCHANGE because for showing the correct frequency
+	 * change order of between devfreq device and passive devfreq device.
+	 */
+	if (trace_devfreq_frequency_enabled() && new_freq != cur_freq)
+		trace_devfreq_frequency(devfreq, new_freq, cur_freq);
+
 	freqs.new = new_freq;
 	devfreq_notify_transition(devfreq, &freqs, DEVFREQ_POSTCHANGE);
 
diff --git a/include/trace/events/devfreq.h b/include/trace/events/devfreq.h
index bd36d28d16bc..7627c620bbda 100644
--- a/include/trace/events/devfreq.h
+++ b/include/trace/events/devfreq.h
@@ -8,6 +8,34 @@
 #include <linux/devfreq.h>
 #include <linux/tracepoint.h>
 
+TRACE_EVENT(devfreq_frequency,
+	TP_PROTO(struct devfreq *devfreq, unsigned long freq,
+		 unsigned long prev_freq),
+
+	TP_ARGS(devfreq, freq, prev_freq),
+
+	TP_STRUCT__entry(
+		__string(dev_name, dev_name(&devfreq->dev))
+		__field(unsigned long, freq)
+		__field(unsigned long, prev_freq)
+		__field(unsigned long, busy_time)
+		__field(unsigned long, total_time)
+	),
+
+	TP_fast_assign(
+		__assign_str(dev_name, dev_name(&devfreq->dev));
+		__entry->freq = freq;
+		__entry->prev_freq = prev_freq;
+		__entry->busy_time = devfreq->last_status.busy_time;
+		__entry->total_time = devfreq->last_status.total_time;
+	),
+
+	TP_printk("dev_name=%-30s freq=%-12lu prev_freq=%-12lu load=%-2lu",
+		__get_str(dev_name), __entry->freq, __entry->prev_freq,
+		__entry->total_time == 0 ? 0 :
+			(100 * __entry->busy_time) / __entry->total_time)
+);
+
 TRACE_EVENT(devfreq_monitor,
 	TP_PROTO(struct devfreq *devfreq),
 
-- 
2.17.1