linux-kernel - [PATCH 1/2 v2] tools/tracing/rtla: osnoise_hist: use total duration for average calculation

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Date:   Tue,  3 Jan 2023 11:33:59 +0100
From:   Andreas Ziegler <br015@...iko.net>
To:     Daniel Bristot de Oliveira <bristot@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>
Cc:     linux-trace-devel@...r.kernel.org, linux-kernel@...r.kernel.org,
        Andreas Ziegler <br015@...iko.net>
Subject: [PATCH 1/2 v2] tools/tracing/rtla: osnoise_hist: use total duration for average calculation

Sampled durations must be weighted by observed quantity, to arrive at a correct
average duration value.

Perform calculation of total duration by summing (duration * count).

Fixes: 829a6c0b5698 ("rtla/osnoise: Add the hist mode")

Signed-off-by: Andreas Ziegler <br015@...iko.net>
---
Changes v1 -> v2:
 - add 'Fixes' line (Daniel)

 tools/tracing/rtla/src/osnoise_hist.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/tracing/rtla/src/osnoise_hist.c b/tools/tracing/rtla/src/osnoise_hist.c
index 5d7ea479ac89..fe34452fc4ec 100644
--- a/tools/tracing/rtla/src/osnoise_hist.c
+++ b/tools/tracing/rtla/src/osnoise_hist.c
@@ -121,6 +121,7 @@ static void osnoise_hist_update_multiple(struct osnoise_tool *tool, int cpu,
 {
 	struct osnoise_hist_params *params = tool->params;
 	struct osnoise_hist_data *data = tool->data;
+	unsigned long long total_duration;
 	int entries = data->entries;
 	int bucket;
 	int *hist;
@@ -131,10 +132,12 @@ static void osnoise_hist_update_multiple(struct osnoise_tool *tool, int cpu,
 	if (data->bucket_size)
 		bucket = duration / data->bucket_size;
 
+	total_duration = duration * count;
+
 	hist = data->hist[cpu].samples;
 	data->hist[cpu].count += count;
 	update_min(&data->hist[cpu].min_sample, &duration);
-	update_sum(&data->hist[cpu].sum_sample, &duration);
+	update_sum(&data->hist[cpu].sum_sample, &total_duration);
 	update_max(&data->hist[cpu].max_sample, &duration);
 
 	if (bucket < entries)
-- 
2.34.1