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From: Ben Gainey <ben.gainey@arm.com>
To: linux-perf-users@vger.kernel.org,
	linux-kernel@vger.kernel.org
Cc: peterz@infradead.org,
	mingo@redhat.com,
	acme@kernel.org,
	mark.rutland@arm.com,
	alexander.shishkin@linux.intel.com,
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	adrian.hunter@intel.com,
	james.clark@arm.com,
	Ben Gainey <ben.gainey@arm.com>
Subject: [PATCH v2 2/4] tools/perf: Track where perf_sample_ids need per-thread periods
Date: Thu,  8 Feb 2024 13:10:48 +0000
Message-ID: <20240208131050.2406183-3-ben.gainey@arm.com>
In-Reply-To: <20240208131050.2406183-1-ben.gainey@arm.com>
References: <20240208131050.2406183-1-ben.gainey@arm.com>
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When PERF_SAMPLE_READ is used with inherit+inherit_stat the perf_sample_id is no longer
globally unique, but instead is unique per each inherited thread.

Track this fact in perf_sample_ids as it will be needed to correctly calculate the
period.

Signed-off-by: Ben Gainey <ben.gainey@arm.com>
---
 tools/lib/perf/evlist.c                 | 1 +
 tools/lib/perf/evsel.c                  | 7 +++++++
 tools/lib/perf/include/internal/evsel.h | 7 +++++++
 3 files changed, 15 insertions(+)

diff --git a/tools/lib/perf/evlist.c b/tools/lib/perf/evlist.c
index 058e3ff10f9b..c585c49491a5 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 c07160953224..dd60ee0557d8 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.inherit
+		&& evsel->attr.inherit_stat;
+}
+
 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 5cd220a61962..97658f1c9ca3 100644
--- a/tools/lib/perf/include/internal/evsel.h
+++ b/tools/lib/perf/include/internal/evsel.h
@@ -36,6 +36,11 @@ struct perf_sample_id {
 
 	/* Holds total ID period value for PERF_SAMPLE_READ processing. */
 	u64			 period;
+
+	/* When inherit+inherit_stat is combined with PERF_SAMPLE_READ, the
+	 * period value is per (sample_id, thread) tuple, rather than per
+	 * sample_id. */
+	bool 			 period_per_thread;
 };
 
 struct perf_evsel {
@@ -88,4 +93,6 @@ 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 */
-- 
2.43.0