linux-kernel - [PATCH v6 2/4] tools/perf: Track where perf_sample

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Date: Tue, 21 May 2024 14:30:27 +0100
From: Ben Gainey <ben.gainey@....com>
To: peterz@...radead.org,
	mingo@...hat.com,
	acme@...nel.org,
	namhyung@...nel.org
Cc: james.clark@....com,
	mark.rutland@....com,
	alexander.shishkin@...ux.intel.com,
	jolsa@...nel.org,
	irogers@...gle.com,
	adrian.hunter@...el.com,
	linux-perf-users@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Ben Gainey <ben.gainey@....com>
Subject: [PATCH v6 2/4] tools/perf: Track where perf_sample_ids need per-thread periods

perf_sample_ids and related evlist/evsel code are modified to track
which events combine inherit+PERF_SAMPLE_READ+PERF_SAMPLE_TID.

Events with this combination of properties must be handled differently
when calculating each sample period. They must use the combination
of (ID + TID) to uniquely identify each distinct sequence of values.

Signed-off-by: Ben Gainey <ben.gainey@....com>
---
 tools/lib/perf/evlist.c                 | 1 +
 tools/lib/perf/evsel.c                  | 7 +++++++
 tools/lib/perf/include/internal/evsel.h | 9 +++++++++
 3 files changed, 17 insertions(+)

diff --git a/tools/lib/perf/evlist.c b/tools/lib/perf/evlist.c
index c6d67fc9e57ef..d17288eeaee48 100644
--- a/tools/lib/perf/evlist.c
+++ b/tools/lib/perf/evlist.c
@@ -255,6 +255,7 @@ static void perf_evlist__id_hash(struct perf_evlist *evlist,
 
 	sid->id = id;
 	sid->evsel = evsel;
+	sid->period_per_thread = perf_evsel__attr_has_per_thread_sample_period(evsel);
 	hash = hash_64(sid->id, PERF_EVLIST__HLIST_BITS);
 	hlist_add_head(&sid->node, &evlist->heads[hash]);
 }
diff --git a/tools/lib/perf/evsel.c b/tools/lib/perf/evsel.c
index c07160953224a..f7abb879f416e 100644
--- a/tools/lib/perf/evsel.c
+++ b/tools/lib/perf/evsel.c
@@ -537,6 +537,13 @@ void perf_evsel__free_id(struct perf_evsel *evsel)
 	evsel->ids = 0;
 }
 
+bool perf_evsel__attr_has_per_thread_sample_period(struct perf_evsel *evsel)
+{
+	return (evsel->attr.sample_type & PERF_SAMPLE_READ)
+		&& (evsel->attr.sample_type & PERF_SAMPLE_TID)
+		&& evsel->attr.inherit;
+}
+
 void perf_counts_values__scale(struct perf_counts_values *count,
 			       bool scale, __s8 *pscaled)
 {
diff --git a/tools/lib/perf/include/internal/evsel.h b/tools/lib/perf/include/internal/evsel.h
index 5cd220a61962e..f8de2bf89c76b 100644
--- a/tools/lib/perf/include/internal/evsel.h
+++ b/tools/lib/perf/include/internal/evsel.h
@@ -36,6 +36,13 @@ struct perf_sample_id {
 
 	/* Holds total ID period value for PERF_SAMPLE_READ processing. */
 	u64			 period;
+
+	/*
+	 * When inherit is combined with PERF_SAMPLE_READ, the period value is
+	 * per (id, thread) tuple, rather than per id, so use the stream_id to
+	 * uniquely identify the period, rather than the id.
+	 */
+	bool			 period_per_thread;
 };
 
 struct perf_evsel {
@@ -88,4 +95,6 @@ int perf_evsel__apply_filter(struct perf_evsel *evsel, const char *filter);
 int perf_evsel__alloc_id(struct perf_evsel *evsel, int ncpus, int nthreads);
 void perf_evsel__free_id(struct perf_evsel *evsel);
 
+bool perf_evsel__attr_has_per_thread_sample_period(struct perf_evsel *evsel);
+
 #endif /* __LIBPERF_INTERNAL_EVSEL_H */
-- 
2.45.1