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

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Message-ID: <fefd9ded-b9d8-3b01-de39-7ff147206c84@kernel.org>
Date:   Thu, 12 Jan 2023 15:32:36 +0100
From:   Daniel Bristot de Oliveira <bristot@...nel.org>
To:     Andreas Ziegler <br015@...iko.net>,
        Steven Rostedt <rostedt@...dmis.org>
Cc:     linux-trace-devel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2 v2] tools/tracing/rtla: osnoise_hist: use total
 duration for average calculation

On 1/3/23 11:33, Andreas Ziegler wrote:
> 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>

Acked-by: Daniel Bristot de Oliveira <bristot@...nel.org>
-- Daniel

> ---
> 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)