Re: [RFC PATCH v2 02/14] perf stat: Implement standard console (STD) formatting callbacks

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] Missing trailing newline for interval output in metric-only mode.
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commit 7c6854720d44b02ec256a0c56e408fbe8b0ead8f
Author: Ian Rogers <irogers@google.com>

perf stat: Implement standard console (STD) formatting callbacks

This commit implements standard console formatting callbacks inside
util/stat-print-std.c. It replaces the empty stubs by buffering
traversal streams using format-private DOM nodes and unified aggregation
helpers.

> diff --git a/tools/perf/util/stat-print-std.c b/tools/perf/util/stat-print-std.c
> index 83987e97c8895..aa4a083bb85ab 100644
> --- a/tools/perf/util/stat-print-std.c
> +++ b/tools/perf/util/stat-print-std.c

[ ... ]

> +static void print_footer_std(const struct perf_stat_config *config)
> +{
> +	double avg = avg_stats(config->walltime_nsecs_stats) / NSEC_PER_SEC;
> +	FILE *output = config->output;
> +
> +	if (config->interval)
> +		return;

[ ... ]

> +static int std_metric_only_print_end(void *ctx, const struct perf_stat_config *config)
> +{

[ ... ]

> +	/* Print values */
> +	list_for_each_entry_safe(b, tmp, &ps->queued_metrics, list) {
> +		if (b->aggr_idx != current_aggr) {
> +			if (current_aggr != -2)
> +				fprintf(out, "\n");

[ ... ]

> +		fprintf(out, "%*s ", mlen, str);
> +		free(str);
> +
> +		list_del(&b->list);
> +		free(b->name);
> +		free(b->unit);
> +		free(b);
> +	}
> +	print_footer_std(config);

[Severity: Low]
Will this omit a trailing newline when running perf stat in interval mode?

It looks like the traversal over queued_metrics prints newlines between
aggregation blocks, but relies on print_footer_std() to close out the
final line.

However, as shown above, print_footer_std() returns early if
config->interval is true:

static void print_footer_std(const struct perf_stat_config *config)
{
    ...
    if (config->interval)
        return;

Could this cause the output for successive intervals to be concatenated
directly onto the same line without separation?

> +	return 0;
> +
> +cleanup:

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260525231900.3527228-1-irogers@google.com?part=2