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

Ian Rogers
2025-03-18T04:14:59Z

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/}'
```

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

--
2.49.0.rc1.451.g8f38331e32-goog