[PATCH v2 1/4] perf parse-events: Avoid scanning PMUs that can't contain events

[Ian Rogers]

Add perf_pmus__scan_for_event that only reads sysfs for pmus that
could contain a given event.

Signed-off-by: Ian Rogers <irog...@google.com>
---
 tools/perf/util/parse-events.c |  4 ++--
 tools/perf/util/pmus.c         | 35 ++++++++++++++++++++++++++++++++++
 tools/perf/util/pmus.h         |  1 +
 3 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 5152fd5a6ead..d77af1d24985 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -434,7 +434,7 @@ int parse_events_add_cache(struct list_head *list, int 
*idx, const char *name,
        const char *config_name = get_config_name(parsed_terms);
        const char *metric_id = get_config_metric_id(parsed_terms);
 
-       while ((pmu = perf_pmus__scan(pmu)) != NULL) {
+       while ((pmu = perf_pmus__scan_for_event(pmu, name)) != NULL) {
                LIST_HEAD(config_terms);
                struct perf_event_attr attr;
                int ret;
@@ -1585,7 +1585,7 @@ int parse_events_multi_pmu_add(struct parse_events_state 
*parse_state,
 
        INIT_LIST_HEAD(list);
 
-       while ((pmu = perf_pmus__scan(pmu)) != NULL) {
+       while ((pmu = perf_pmus__scan_for_event(pmu, event_name)) != NULL) {
                bool auto_merge_stats;
 
                if (parse_events__filter_pmu(parse_state, pmu))
diff --git a/tools/perf/util/pmus.c b/tools/perf/util/pmus.c
index b99292de7669..f2706c395509 100644
--- a/tools/perf/util/pmus.c
+++ b/tools/perf/util/pmus.c
@@ -350,6 +350,41 @@ struct perf_pmu *perf_pmus__scan_core(struct perf_pmu *pmu)
        return NULL;
 }
 
+struct perf_pmu *perf_pmus__scan_for_event(struct perf_pmu *pmu, const char 
*event)
+{
+       bool use_core_pmus = !pmu || pmu->is_core;
+
+       if (!pmu) {
+               /* Hwmon filename values that aren't used. */
+               enum hwmon_type type;
+               int number;
+               /*
+                * Core PMUs, other sysfs PMUs and tool PMU can take all event
+                * types or aren't wother optimizing for.
+                */
+               unsigned int to_read_pmus =  PERF_TOOL_PMU_TYPE_PE_CORE_MASK |
+                       PERF_TOOL_PMU_TYPE_PE_OTHER_MASK |
+                       PERF_TOOL_PMU_TYPE_TOOL_MASK;
+
+               /* Could the event be a hwmon event? */
+               if (parse_hwmon_filename(event, &type, &number, /*item=*/NULL, 
/*alarm=*/NULL))
+                       to_read_pmus |= PERF_TOOL_PMU_TYPE_HWMON_MASK;
+
+               pmu_read_sysfs(to_read_pmus);
+               pmu = list_prepare_entry(pmu, &core_pmus, list);
+       }
+       if (use_core_pmus) {
+               list_for_each_entry_continue(pmu, &core_pmus, list)
+                       return pmu;
+
+               pmu = NULL;
+               pmu = list_prepare_entry(pmu, &other_pmus, list);
+       }
+       list_for_each_entry_continue(pmu, &other_pmus, list)
+               return pmu;
+       return NULL;
+}
+
 static struct perf_pmu *perf_pmus__scan_skip_duplicates(struct perf_pmu *pmu)
 {
        bool use_core_pmus = !pmu || pmu->is_core;
diff --git a/tools/perf/util/pmus.h b/tools/perf/util/pmus.h
index 8def20e615ad..213ee65306d6 100644
--- a/tools/perf/util/pmus.h
+++ b/tools/perf/util/pmus.h
@@ -19,6 +19,7 @@ struct perf_pmu *perf_pmus__find_by_type(unsigned int type);
 
 struct perf_pmu *perf_pmus__scan(struct perf_pmu *pmu);
 struct perf_pmu *perf_pmus__scan_core(struct perf_pmu *pmu);
+struct perf_pmu *perf_pmus__scan_for_event(struct perf_pmu *pmu, const char 
*event);
 
 const struct perf_pmu *perf_pmus__pmu_for_pmu_filter(const char *str);
 
-- 
2.49.0.395.g12beb8f557-goog