[PATCH 02/10] perf, tools, stat: Force --per-core mode for .agg-per-core aliases

[Andi Kleen]

From: Andi Kleen <ak@xxxxxxxxxxxxxxx>

When an event alias is used that the kernel marked as .agg-per-core, force
--per-core mode (and also require -a and forbid cgroups or per thread mode).
This in term means, --topdown forces --per-core mode.

This is needed for TopDown in SMT mode, because it needs to measure
all threads in a core together and merge the values to compute the correct
percentages of how the pipeline is limited.

We do this if any alias is agg-per-core.

Add the code to parse the .agg-per-core attributes and propagate
the information to the evsel. Then the main stat code does
the necessary checks and forces per core mode.

Open issue: in combination with -C ... we get wrong values. I think that's
a existing bug that needs to be debugged/fixed separately.

Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx>
---
 tools/perf/builtin-stat.c      | 18 ++++++++++++++++++
 tools/perf/util/evsel.h        |  1 +
 tools/perf/util/parse-events.c |  1 +
 tools/perf/util/pmu.c          | 23 +++++++++++++++++++++++
 tools/perf/util/pmu.h          |  2 ++
 5 files changed, 45 insertions(+)

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 4777355..0c7cdda 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -1540,6 +1540,7 @@ static int add_default_attributes(void)
 
 int cmd_stat(int argc, const char **argv, const char *prefix __maybe_unused)
 {
+	struct perf_evsel *counter;
 	const char * const stat_usage[] = {
 		"perf stat [<options>] [<command>]",
 		NULL
@@ -1674,6 +1675,23 @@ int cmd_stat(int argc, const char **argv, const char *prefix __maybe_unused)
 	if (add_default_attributes())
 		goto out;
 
+	evlist__for_each (evsel_list, counter) {
+		/* Enable per core mode if only a single event requires it. */
+		if (counter->agg_per_core) {
+			if (stat_config.aggr_mode != AGGR_GLOBAL &&
+			    stat_config.aggr_mode != AGGR_CORE) {
+				pr_err("per core event configuration requires per core mode\n");
+				goto out;
+			}
+			stat_config.aggr_mode = AGGR_CORE;
+			if (nr_cgroups || !target__has_cpu(&target)) {
+				pr_err("per core event configuration requires system-wide mode (-a)\n");
+				goto out;
+			}
+			break;
+		}
+	}
+
 	target__validate(&target);
 
 	if (perf_evlist__create_maps(evsel_list, &target) < 0) {
diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 5ded1fc..efc7f7c 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -114,6 +114,7 @@ struct perf_evsel {
 	bool			tracking;
 	bool			per_pkg;
 	bool			precise_max;
+	bool			agg_per_core;
 	/* parse modifier helper */
 	int			exclude_GH;
 	int			nr_members;
diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 6fc8cd7..66d8ebd 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -1027,6 +1027,7 @@ int parse_events_add_pmu(struct parse_events_evlist *data,
 		evsel->unit = info.unit;
 		evsel->scale = info.scale;
 		evsel->per_pkg = info.per_pkg;
+		evsel->agg_per_core = info.agg_per_core;
 		evsel->snapshot = info.snapshot;
 	}
 
diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 8a520e9..5a52dac 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -189,6 +189,23 @@ perf_pmu__parse_per_pkg(struct perf_pmu_alias *alias, char *dir, char *name)
 	return 0;
 }
 
+static void
+perf_pmu__parse_agg_per_core(struct perf_pmu_alias *alias, char *dir, char *name)
+{
+	char path[PATH_MAX];
+	FILE *f;
+	int flag;
+
+	snprintf(path, PATH_MAX, "%s/%s.agg-per-core", dir, name);
+
+	f = fopen(path, "r");
+	if (f && fscanf(f, "%d", &flag) == 1) {
+		alias->agg_per_core = flag != 0;
+		fclose(f);
+	}
+}
+
+
 static int perf_pmu__parse_snapshot(struct perf_pmu_alias *alias,
 				    char *dir, char *name)
 {
@@ -237,6 +254,7 @@ static int __perf_pmu__new_alias(struct list_head *list, char *dir, char *name,
 		perf_pmu__parse_scale(alias, dir, name);
 		perf_pmu__parse_per_pkg(alias, dir, name);
 		perf_pmu__parse_snapshot(alias, dir, name);
+		perf_pmu__parse_agg_per_core(alias, dir, name);
 	}
 
 	list_add_tail(&alias->list, list);
@@ -271,6 +289,8 @@ static inline bool pmu_alias_info_file(char *name)
 		return true;
 	if (len > 9 && !strcmp(name + len - 9, ".snapshot"))
 		return true;
+	if (len > 13 && !strcmp(name + len - 13, ".agg-per-core"))
+		return true;
 
 	return false;
 }
@@ -847,6 +867,7 @@ int perf_pmu__check_alias(struct perf_pmu *pmu, struct list_head *head_terms,
 	int ret;
 
 	info->per_pkg = false;
+	info->agg_per_core = false;
 
 	/*
 	 * Mark unit and scale as not set
@@ -870,6 +891,8 @@ int perf_pmu__check_alias(struct perf_pmu *pmu, struct list_head *head_terms,
 
 		if (alias->per_pkg)
 			info->per_pkg = true;
+		if (alias->agg_per_core)
+			info->agg_per_core = true;
 
 		list_del(&term->list);
 		free(term);
diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
index 5d7e844..5a43719 100644
--- a/tools/perf/util/pmu.h
+++ b/tools/perf/util/pmu.h
@@ -32,6 +32,7 @@ struct perf_pmu_info {
 	double scale;
 	bool per_pkg;
 	bool snapshot;
+	bool agg_per_core;
 };
 
 #define UNIT_MAX_LEN	31 /* max length for event unit name */
@@ -44,6 +45,7 @@ struct perf_pmu_alias {
 	double scale;
 	bool per_pkg;
 	bool snapshot;
+	bool agg_per_core;
 };
 
 struct perf_pmu *perf_pmu__find(const char *name);
-- 
2.4.3

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