[PATCH v6 2/4] tools/perf: Track where perf_sample_ids need per-thread periods

From: Ben Gainey
Date: Tue May 21 2024 - 09:31:16 EST


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@xxxxxxx>
---
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