Re: [PATCH v1 5/5] perf parse-events: Add debug dump of evlist if reordered

Liang, Kan
2025-04-02T15:34:06Z

On 2025-03-18 12:14 a.m., Ian Rogers wrote:
> Add debug verbose output to show how evsels were reordered by
> parse_events__sort_events_and_fix_groups. For example:
> ```
> $ perf record -v -e '{instructions,cycles}' true
> Using CPUID GenuineIntel-6-B7-1
> WARNING: events were regrouped to match PMUs
> evlist after sorting/fixing: '{cpu_atom/instructions/,cpu_atom/cycles/},{cpu_core/instructions/,cpu_core/cycles/}'
> ```
>

Thanks. This is very nice.
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
> tools/perf/util/parse-events.c | 16 +++++++++++++---
> 1 file changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
> index 5152fd5a6ead..cb76796bc5c7 100644
> --- a/tools/perf/util/parse-events.c
> +++ b/tools/perf/util/parse-events.c
> @@ -28,6 +28,7 @@
> #include "util/evsel_config.h"
> #include "util/event.h"
> #include "util/bpf-filter.h"
> +#include "util/stat.h"
> #include "util/util.h"
> #include "tracepoint.h"
>
> @@ -2196,14 +2197,23 @@ int __parse_events(struct evlist *evlist, const char *str, const char *pmu_filte
> if (ret2 < 0)
> return ret;
>
> - if (ret2 && warn_if_reordered && !parse_state.wild_card_pmus)
> - pr_warning("WARNING: events were regrouped to match PMUs\n");
> -
> /*
> * Add list to the evlist even with errors to allow callers to clean up.
> */
> evlist__splice_list_tail(evlist, &parse_state.list);
>
> + if (ret2 && warn_if_reordered && !parse_state.wild_card_pmus) {
> + pr_warning("WARNING: events were regrouped to match PMUs\n");
> +
> + if (verbose > 0) {
> + struct strbuf sb = STRBUF_INIT;
> +
> + evlist__uniquify_name(evlist);
> + evlist__format_evsels(evlist, &sb);

Ah, I know why you want a full list now.

A full list should be OK for pr_debug. But it may be a problem for
pr_err in patch 3. Maybe add a parameter in evlist__format_evsels() to
control if printing the full list.

Thanks,
Kan

> + pr_debug("evlist after sorting/fixing: '%s'\n", sb.buf);
> + strbuf_release(&sb);
> + }
> + }
> if (!ret) {
> struct evsel *last;
>