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).

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

Fixes: 829a6c0b ("rtla/osnoise: Add the hist mode")
Signed-off-by: Andreas Ziegler <br015@umbiko.net>
Acked-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

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)