[PATCH v2 01/16] perf pmus: Expose duplicate uncore PMU scanning helpers

[Ian Rogers <irogers@google.com>]

Export perf_pmus__scan_skip_duplicates() and add
perf_pmu__num_duplicates() to count numbered PMU instances sharing a
common prefix (such as uncore_imc_0..uncore_imc_7) so subcommands like
'perf sysinfo' can collapse duplicate uncore PMUs by default and report
their instance count.

Signed-off-by: Ian Rogers <irogers@google.com>
---
 tools/perf/util/pmus.c | 26 +++++++++++++++++++++++++-
 tools/perf/util/pmus.h | 21 +++++++++++++++++++++
 2 files changed, 46 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/pmus.c b/tools/perf/util/pmus.c
index b924ff6180e4..931a129bb45b 100644
--- a/tools/perf/util/pmus.c
+++ b/tools/perf/util/pmus.c
@@ -485,7 +485,7 @@ struct perf_pmu *perf_pmus__scan_matching_wildcard(struct perf_pmus *pmus,
 	return NULL;
 }
 
-static struct perf_pmu *
+struct perf_pmu *
 perf_pmus__scan_skip_duplicates(struct perf_pmus *pmus, struct perf_pmu *pmu)
 {
 	bool use_core_pmus = !pmu || pmu->is_core;
@@ -522,6 +522,30 @@ perf_pmus__scan_skip_duplicates(struct perf_pmus *pmus, struct perf_pmu *pmu)
 	return NULL;
 }
 
+size_t perf_pmu__num_duplicates(const struct perf_pmu *pmu)
+{
+	const struct list_head *head;
+	const struct perf_pmu *pos = pmu;
+	size_t base_len;
+	size_t count = 1;
+
+	/* Core PMUs are never duplicates, see perf_pmus__scan_skip_duplicates(). */
+	if (!pmu || !pmu->pmus || pmu->is_core)
+		return 1;
+
+	head = &pmu->pmus->other_pmus;
+	base_len = pmu_name_len_no_suffix(pmu->name ?: "");
+	list_for_each_entry_continue(pos, head, list) {
+		size_t pos_len = pmu_name_len_no_suffix(pos->name ?: "");
+
+		if (pos_len != base_len ||
+		    strncmp(pmu->name ?: "", pos->name ?: "", base_len))
+			break;
+		count++;
+	}
+	return count;
+}
+
 struct perf_pmu *perf_pmus__scan_for_uncore_id(struct perf_pmus *pmus,
 					       struct perf_pmu *pmu, const char *compat)
 {
diff --git a/tools/perf/util/pmus.h b/tools/perf/util/pmus.h
index 2b784cf648f3..44b5dc2fd36c 100644
--- a/tools/perf/util/pmus.h
+++ b/tools/perf/util/pmus.h
@@ -134,6 +134,26 @@ struct perf_pmu *perf_pmus__scan(struct perf_pmus *pmus, struct perf_pmu *pmu);
  */
 struct perf_pmu *perf_pmus__scan_core(struct perf_pmus *pmus, struct perf_pmu *pmu);
 
+/**
+ * perf_pmus__scan_skip_duplicates() - Iterate over PMUs in @pmus, skipping
+ *                                     numbered duplicate instances of
+ *                                     non-core PMUs.
+ * @pmus: The PMU collection to scan.
+ * @pmu: Previous PMU returned, or NULL to start from the first PMU.
+ *
+ * Return: Next distinct prefix struct perf_pmu, or NULL when done.
+ */
+struct perf_pmu *perf_pmus__scan_skip_duplicates(struct perf_pmus *pmus, struct perf_pmu *pmu);
+
+/**
+ * perf_pmu__num_duplicates() - Count consecutive PMUs sharing @pmu's prefix.
+ * @pmu: Representative PMU returned by perf_pmus__scan_skip_duplicates().
+ *
+ * Return: Number of PMU instances (including @pmu) sharing its base name,
+ * always 1 for core PMUs.
+ */
+size_t perf_pmu__num_duplicates(const struct perf_pmu *pmu);
+
 /**
  * perf_pmus__scan_for_event() - Iterate over PMUs in @pmus that have @event.
  * @pmus: The PMU collection to scan.
@@ -260,6 +280,7 @@ struct perf_pmu *perf_pmus__add_test_hwmon_pmu(struct perf_pmus *pmus,
  * Return: Pointer to the fake struct perf_pmu.
  */
 struct perf_pmu *perf_pmus__fake_pmu(void);
+
 /**
  * perf_pmus__find_core_pmu() - Return the first core PMU in @pmus.
  * @pmus: The PMU collection to search.
-- 
2.56.1.703.gf848ed807c-goog