perf pmus: Skip duplicate PMUs and don't print list suffix by default

Add a PMUs scan that ignores duplicates. When there are multiple PMUs
that differ only by suffix, by default just list the first one and
skip all others. The scan routine checks that the PMU names match but
doesn't enforce that the numbers are consecutive as for some PMUs
there are gaps. If "-v" is passed to "perf list" then list all PMUs.

With the previous change duplicate PMUs are no longer printed but the
suffix of the first is printed. When duplicate PMUs are being skipped
avoid printing the suffix.

Before:

  $ perf list
  ...
    uncore_imc_free_running_0/data_read/               [Kernel PMU event]
    uncore_imc_free_running_0/data_total/              [Kernel PMU event]
    uncore_imc_free_running_0/data_write/              [Kernel PMU event]
    uncore_imc_free_running_1/data_read/               [Kernel PMU event]
    uncore_imc_free_running_1/data_total/              [Kernel PMU event]
    uncore_imc_free_running_1/data_write/              [Kernel PMU event]

After:

  $ perf list
  ...
    uncore_imc_free_running/data_read/                 [Kernel PMU event]
    uncore_imc_free_running/data_total/                [Kernel PMU event]
    uncore_imc_free_running/data_write/                [Kernel PMU event]
  ...
  $ perf list -v
    uncore_imc_free_running_0/data_read/               [Kernel PMU event]
    uncore_imc_free_running_0/data_total/              [Kernel PMU event]
    uncore_imc_free_running_0/data_write/              [Kernel PMU event]
    uncore_imc_free_running_1/data_read/               [Kernel PMU event]
    uncore_imc_free_running_1/data_total/              [Kernel PMU event]
    uncore_imc_free_running_1/data_write/              [Kernel PMU event]
  ...

Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Link: https://lore.kernel.org/r/20230825135237.921058-3-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/builtin-list.c

@@ -434,6 +434,13 @@ static void json_print_metric(void *ps __maybe_unused, const char *group,
 	strbuf_release(&buf);
 }
 
+static bool default_skip_duplicate_pmus(void *ps)
+{
+	struct print_state *print_state = ps;
+
+	return !print_state->long_desc;
+}
+
 int cmd_list(int argc, const char **argv)
 {
 	int i, ret = 0;
@@ -445,6 +452,7 @@ int cmd_list(int argc, const char **argv)
 		.print_end = default_print_end,
 		.print_event = default_print_event,
 		.print_metric = default_print_metric,
+		.skip_duplicate_pmus = default_skip_duplicate_pmus,
 	};
 	const char *cputype = NULL;
 	const char *unit_name = NULL;

tools/perf/util/pmu.c

@@ -1578,7 +1578,9 @@ int perf_pmu__find_event(struct perf_pmu *pmu, const char *event, void *state, p
 		.cb = cb,
 	};
 
-	return perf_pmu__for_each_event(pmu, &args, find_event_callback);
+	/* Sub-optimal, but function is only used by tests. */
+	return perf_pmu__for_each_event(pmu, /*skip_duplicate_pmus=*/ false,
+					&args, find_event_callback);
 }
 
 static void perf_pmu__del_formats(struct list_head *formats)
@@ -1652,10 +1654,13 @@ static int sub_non_neg(int a, int b)
 }
 
 static char *format_alias(char *buf, int len, const struct perf_pmu *pmu,
-			  const struct perf_pmu_alias *alias)
+			  const struct perf_pmu_alias *alias, bool skip_duplicate_pmus)
 {
 	struct parse_events_term *term;
-	int used = snprintf(buf, len, "%s/%s", pmu->name, alias->name);
+	int pmu_name_len = skip_duplicate_pmus
+		? pmu_name_len_no_suffix(pmu->name, /*num=*/NULL)
+		: (int)strlen(pmu->name);
+	int used = snprintf(buf, len, "%.*s/%s", pmu_name_len, pmu->name, alias->name);
 
 	list_for_each_entry(term, &alias->terms, list) {
 		if (term->type_val == PARSE_EVENTS__TERM_TYPE_STR)
@@ -1677,7 +1682,8 @@ static char *format_alias(char *buf, int len, const struct perf_pmu *pmu,
 	return buf;
 }
 
-int perf_pmu__for_each_event(struct perf_pmu *pmu, void *state, pmu_event_callback cb)
+int perf_pmu__for_each_event(struct perf_pmu *pmu, bool skip_duplicate_pmus,
+			     void *state, pmu_event_callback cb)
 {
 	char buf[1024];
 	struct perf_pmu_alias *event;
@@ -1696,7 +1702,8 @@ int perf_pmu__for_each_event(struct perf_pmu *pmu, void *state, pmu_event_callba
 			info.name = event->name;
 			buf_used = 0;
 		} else {
-			info.name = format_alias(buf, sizeof(buf), pmu, event);
+			info.name = format_alias(buf, sizeof(buf), pmu, event,
+						 skip_duplicate_pmus);
 			if (pmu->is_core) {
 				info.alias = info.name;
 				info.name = event->name;

tools/perf/util/pmu.h

@@ -212,7 +212,8 @@ bool perf_pmu__supports_legacy_cache(const struct perf_pmu *pmu);
 bool perf_pmu__auto_merge_stats(const struct perf_pmu *pmu);
 bool perf_pmu__have_event(struct perf_pmu *pmu, const char *name);
 size_t perf_pmu__num_events(struct perf_pmu *pmu);
-int perf_pmu__for_each_event(struct perf_pmu *pmu, void *state, pmu_event_callback cb);
+int perf_pmu__for_each_event(struct perf_pmu *pmu, bool skip_duplicate_pmus,
+			     void *state, pmu_event_callback cb);
 bool pmu__name_match(const struct perf_pmu *pmu, const char *pmu_name);
 
 /**

tools/perf/util/pmus.c

@@ -36,7 +36,7 @@ static LIST_HEAD(other_pmus);
 static bool read_sysfs_core_pmus;
 static bool read_sysfs_all_pmus;
 
-static int pmu_name_len_no_suffix(const char *str, unsigned long *num)
+int pmu_name_len_no_suffix(const char *str, unsigned long *num)
 {
 	int orig_len, len;
 
@@ -276,6 +276,43 @@ struct perf_pmu *perf_pmus__scan_core(struct perf_pmu *pmu)
 	return NULL;
 }
 
+static struct perf_pmu *perf_pmus__scan_skip_duplicates(struct perf_pmu *pmu)
+{
+	bool use_core_pmus = !pmu || pmu->is_core;
+	int last_pmu_name_len = 0;
+	const char *last_pmu_name = (pmu && pmu->name) ? pmu->name : "";
+
+	if (!pmu) {
+		pmu_read_sysfs(/*core_only=*/false);
+		pmu = list_prepare_entry(pmu, &core_pmus, list);
+	} else
+		last_pmu_name_len = pmu_name_len_no_suffix(pmu->name ?: "", NULL);
+
+	if (use_core_pmus) {
+		list_for_each_entry_continue(pmu, &core_pmus, list) {
+			int pmu_name_len = pmu_name_len_no_suffix(pmu->name ?: "", /*num=*/NULL);
+
+			if (last_pmu_name_len == pmu_name_len &&
+			    !strncmp(last_pmu_name, pmu->name ?: "", pmu_name_len))
+				continue;
+
+			return pmu;
+		}
+		pmu = NULL;
+		pmu = list_prepare_entry(pmu, &other_pmus, list);
+	}
+	list_for_each_entry_continue(pmu, &other_pmus, list) {
+		int pmu_name_len = pmu_name_len_no_suffix(pmu->name ?: "", /*num=*/NULL);
+
+		if (last_pmu_name_len == pmu_name_len &&
+		    !strncmp(last_pmu_name, pmu->name ?: "", pmu_name_len))
+			continue;
+
+		return pmu;
+	}
+	return NULL;
+}
+
 const struct perf_pmu *perf_pmus__pmu_for_pmu_filter(const char *str)
 {
 	struct perf_pmu *pmu = NULL;
@@ -401,10 +438,17 @@ void perf_pmus__print_pmu_events(const struct print_callbacks *print_cb, void *p
 	int len;
 	struct sevent *aliases;
 	struct events_callback_state state;
+	bool skip_duplicate_pmus = print_cb->skip_duplicate_pmus(print_state);
+	struct perf_pmu *(*scan_fn)(struct perf_pmu *);
+
+	if (skip_duplicate_pmus)
+		scan_fn = perf_pmus__scan_skip_duplicates;
+	else
+		scan_fn = perf_pmus__scan;
 
 	pmu = NULL;
 	len = 0;
-	while ((pmu = perf_pmus__scan(pmu)) != NULL)
+	while ((pmu = scan_fn(pmu)) != NULL)
 		len += perf_pmu__num_events(pmu);
 
 	aliases = zalloc(sizeof(struct sevent) * len);
@@ -418,8 +462,9 @@ void perf_pmus__print_pmu_events(const struct print_callbacks *print_cb, void *p
 		.aliases_len = len,
 		.index = 0,
 	};
-	while ((pmu = perf_pmus__scan(pmu)) != NULL) {
-		perf_pmu__for_each_event(pmu, &state, perf_pmus__print_pmu_events__callback);
+	while ((pmu = scan_fn(pmu)) != NULL) {
+		perf_pmu__for_each_event(pmu, skip_duplicate_pmus, &state,
+					 perf_pmus__print_pmu_events__callback);
 	}
 	qsort(aliases, len, sizeof(struct sevent), cmp_sevent);
 	for (int j = 0; j < len; j++) {

tools/perf/util/pmus.h

@@ -5,6 +5,8 @@
 struct perf_pmu;
 struct print_callbacks;
 
+int pmu_name_len_no_suffix(const char *str, unsigned long *num);
+
 void perf_pmus__destroy(void);
 
 struct perf_pmu *perf_pmus__find(const char *name);

tools/perf/util/print-events.h

@@ -26,6 +26,7 @@ struct print_callbacks {
 			const char *expr,
 			const char *threshold,
 			const char *unit);
+	bool (*skip_duplicate_pmus)(void *print_state);
 };
 
 /** Print all events, the default when no options are specified. */

tools/perf/util/s390-sample-raw.c

@@ -171,7 +171,8 @@ static char *get_counter_name(int set, int nr, struct perf_pmu *pmu)
 	if (!pmu)
 		return NULL;
 
-	perf_pmu__for_each_event(pmu, &data, get_counter_name_callback);
+	perf_pmu__for_each_event(pmu, /*skip_duplicate_pmus=*/ true,
+				 &data, get_counter_name_callback);
 	return data.result;
 }