Re: [PATCH] perf annotate-data: Show event name in the data-type title

[Namhyung Kim]

On Thu, Oct 29, 2026 at 07:15:10AM +0000, Tengda Wu wrote:
> The same data type can be annotated for multiple sampling events, in
> which case the data-type header is printed once per event.  But the
> header only shows the type name and the sample count, so several
> identical-looking headers are emitted and the user cannot tell which
> event each of them corresponds to. E.g.
> 
>   $ perf annotate --data-type=page --stdio --itrace=f
>   Annotate type: 'struct page' in [kernel.kallsyms] (59208 samples):
>   ============================================================================
>    Percent     offset       size  field
>     100.00          0       0x40  struct page      {
>       9.95          0        0x8      long unsigned int   flags;
> 
>   Annotate type: 'struct page' in [kernel.kallsyms] (59480 samples):
>   ============================================================================
>    Percent     offset       size  field
>     100.00          0       0x40  struct page      {
>      10.15          0        0x8      long unsigned int   flags;
> 
> Add the event name to the data-type title in both the TUI browser and
> the stdio output, so each header can be attributed to its event.  For
> group events, use evsel__group_desc() to print the group description
> instead of the leader's name, so the whole group is identified.
> 
> While at it, size the underline in the stdio output dynamically based
> on the length of the header line instead of using a fixed-width string,
> so it keeps matching the header as the text grows.
> 
> Result:
> 
>   $ perf annotate --data-type=page --stdio --itrace=f
>   Annotate type: 'struct page' in [kernel.kallsyms] for l1d-miss (59208 samples):
>   ===============================================================================
>    Percent     offset       size  field
>     100.00          0       0x40  struct page      {
>       9.95          0        0x8      long unsigned int   flags;
> 
>   Annotate type: 'struct page' in [kernel.kallsyms] for l1d-access (59480 samples):
>   =================================================================================
>    Percent     offset       size  field
>     100.00          0       0x40  struct page      {
>      10.15          0        0x8      long unsigned int   flags;
> 
> Signed-off-by: Tengda Wu <wutengda@xxxxxxxxxxxxxxx>

Acked-by: Namhyung Kim <namhyung@xxxxxxxxxx>

Thanks,
Namhyung

> ---
>  tools/perf/ui/browsers/annotate-data.c | 14 +++++++++++---
>  tools/perf/util/annotate-data.c        | 15 ++++++++++++---
>  2 files changed, 23 insertions(+), 6 deletions(-)
> 
> diff --git a/tools/perf/ui/browsers/annotate-data.c b/tools/perf/ui/browsers/annotate-data.c
> index a15608f6ee53..0f778788df4a 100644
> --- a/tools/perf/ui/browsers/annotate-data.c
> +++ b/tools/perf/ui/browsers/annotate-data.c
> @@ -340,11 +340,19 @@ static int browser__show(struct ui_browser *uib)
>  	struct hist_entry *he = uib->priv;
>  	struct annotated_data_type *adt = he->mem_type;
>  	struct annotated_data_browser *browser = get_browser(uib);
> +	struct evsel *evsel = hists_to_evsel(he->hists);
>  	const char *help = "Press 'h' for help on key bindings";
> -	char title[256];
> +	const char *evsel_name = evsel__name(evsel);
> +	char buf[512];
> +	char title[sizeof(buf) + 256];
> +
> +	if (evsel__is_group_event(evsel)) {
> +		evsel__group_desc(evsel, buf, sizeof(buf));
> +		evsel_name = buf;
> +	}
>  
> -	snprintf(title, sizeof(title), "Annotate type: '%s' (%d samples)",
> -		 adt->self.type_name, he->stat.nr_events);
> +	snprintf(title, sizeof(title), "Annotate type: '%s' for %s (%d samples)",
> +		 adt->self.type_name, evsel_name, he->stat.nr_events);
>  
>  	if (ui_browser__show(uib, title, help) < 0)
>  		return -1;
> diff --git a/tools/perf/util/annotate-data.c b/tools/perf/util/annotate-data.c
> index b3de1ca688a2..25e3169ea8ad 100644
> --- a/tools/perf/util/annotate-data.c
> +++ b/tools/perf/util/annotate-data.c
> @@ -2149,16 +2149,23 @@ static void print_annotated_data_header(struct hist_entry *he, struct evsel *evs
>  	int nr_samples = he->stat.nr_events;
>  	int width = 7;
>  	const char *val_hdr = "Percent";
> +	const char *evsel_name = evsel__name(evsel);
> +	char buf[512];
> +	int len;
>  
>  	if (evsel__is_group_event(evsel)) {
>  		struct hist_entry *pair;
>  
>  		list_for_each_entry(pair, &he->pairs.head, pairs.node)
>  			nr_samples += pair->stat.nr_events;
> +
> +		evsel__group_desc(evsel, buf, sizeof(buf));
> +		evsel_name = buf;
>  	}
>  
> -	printf("Annotate type: '%s' in %s (%d samples):\n",
> -	       he->mem_type->self.type_name, dso__name(dso), nr_samples);
> +	len = printf("Annotate type: '%s' in %s for %s (%d samples):\n",
> +		     he->mem_type->self.type_name, dso__name(dso), evsel_name,
> +		     nr_samples);
>  
>  	if (evsel__is_group_event(evsel)) {
>  		struct evsel *pos;
> @@ -2183,7 +2190,9 @@ static void print_annotated_data_header(struct hist_entry *he, struct evsel *evs
>  		val_hdr = "Samples";
>  	}
>  
> -	printf("============================================================================\n");
> +	while (len-- > 1)
> +		putchar('=');
> +	putchar('\n');
>  	printf("%*s %10s %10s  %s\n", (width + 1) * nr_members, val_hdr,
>  	       "offset", "size", "field");
>  }
> 
> base-commit: 151a134a4e6ec66f69db8750c66006f5207f7a9d
> -- 
> 2.34.1
>