linux-kernel - Re: [PATCH] perf data: Prefer sampled CPU when exporting JSON

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Date:   Wed, 22 Jun 2022 10:42:43 -0400
From:   "Shawn M. Chapla" <schapla@...eweavers.com>
To:     linux-kernel@...r.kernel.org
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>
Subject: Re: [PATCH] perf data: Prefer sampled CPU when exporting JSON

On Thu, May 26, 2022 at 04:14:47PM -0400, Shawn M. Chapla wrote:
> When CPU has been explicitly sampled (via --sample-cpu), prefer this
> sampled value over the thread CPU value when exporting to JSON.
> 
> Signed-off-by: Shawn M. Chapla <schapla@...eweavers.com>
> ---
>  tools/perf/util/data-convert-json.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/data-convert-json.c b/tools/perf/util/data-convert-json.c
> index f1ab6edba446..613d6ae82663 100644
> --- a/tools/perf/util/data-convert-json.c
> +++ b/tools/perf/util/data-convert-json.c
> @@ -149,6 +149,7 @@ static int process_sample_event(struct perf_tool *tool,
>  	struct convert_json *c = container_of(tool, struct convert_json, tool);
>  	FILE *out = c->out;
>  	struct addr_location al, tal;
> +	u64 sample_type = __evlist__combined_sample_type(evsel->evlist);
>  	u8 cpumode = PERF_RECORD_MISC_USER;
>  
>  	if (machine__resolve(machine, &al, sample) < 0) {
> @@ -168,7 +169,9 @@ static int process_sample_event(struct perf_tool *tool,
>  	output_json_key_format(out, true, 3, "pid", "%i", al.thread->pid_);
>  	output_json_key_format(out, true, 3, "tid", "%i", al.thread->tid);
>  
> -	if (al.thread->cpu >= 0)
> +	if ((sample_type & PERF_SAMPLE_CPU))
> +		output_json_key_format(out, true, 3, "cpu", "%i", sample->cpu);
> +	else if (al.thread->cpu >= 0)
>  		output_json_key_format(out, true, 3, "cpu", "%i", al.thread->cpu);
>  
>  	output_json_key_string(out, true, 3, "comm", thread__comm_str(al.thread));
> -- 
> 2.36.1
> 

Just checking in to see if anyone has had a chance to take a look at
this yet.

Thanks,
Shawn