linux-kernel - [for-next][PATCH 2/8] tools/tracing/rtla: osnoise_hist: use total duration for average calculation

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Date:   Sat, 18 Feb 2023 15:18:23 -0500
From:   Steven Rostedt <rostedt@...dmis.org>
To:     linux-kernel@...r.kernel.org
Cc:     Masami Hiramatsu <mhiramat@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andreas Ziegler <br015@...iko.net>,
        Daniel Bristot de Oliveira <bristot@...nel.org>
Subject: [for-next][PATCH 2/8] tools/tracing/rtla: osnoise_hist: use total duration for average
 calculation

From: Andreas Ziegler <br015@...iko.net>

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).

Link: https://lkml.kernel.org/r/20230103103400.275566-2-br015@umbiko.net

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

Signed-off-by: Andreas Ziegler <br015@...iko.net>
Acked-by: Daniel Bristot de Oliveira <bristot@...nel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
 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)
-- 
2.39.1