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/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++) {