[PATCH v4 08/16] perf intel-tpebs: Ensure events are opened, factor out finding

Ian Rogers
2025-04-09T06:11:07Z

Factor out finding an tpebs_retire_lat from an evsel. Don't blindly
return when ignoring an open request, which happens after the first
open request, ensure the event was started on a fork of perf record.

Signed-off-by: Ian Rogers <irogers@google.com>
---
tools/perf/util/intel-tpebs.c | 61 +++++++++++++++++++++--------------
1 file changed, 37 insertions(+), 24 deletions(-)

diff --git a/tools/perf/util/intel-tpebs.c b/tools/perf/util/intel-tpebs.c
index c4c818f32239..e42f3ec39a64 100644
--- a/tools/perf/util/intel-tpebs.c
+++ b/tools/perf/util/intel-tpebs.c
@@ -45,6 +45,8 @@ struct tpebs_retire_lat {
int sum;
/* Average of retire_latency, val = sum / count */
double val;
+ /* Has the event been sent to perf record? */
+ bool started;
};

static int evsel__tpebs_start_perf_record(struct evsel *evsel, int control_fd[], int ack_fd[])
@@ -94,6 +96,9 @@ static int evsel__tpebs_start_perf_record(struct evsel *evsel, int control_fd[],
tpebs_cmd.out = -1;
ret = start_command(&tpebs_cmd);
zfree(&tpebs_cmd.argv);
+ list_for_each_entry(t, &tpebs_results, nd)
+ t->started = true;
+
return ret;
}

@@ -214,6 +219,19 @@ static struct tpebs_retire_lat *tpebs_retire_lat__new(struct evsel *evsel)
return result;
}

+static struct tpebs_retire_lat *tpebs_retire_lat__find(struct evsel *evsel)
+{
+ struct tpebs_retire_lat *t;
+
+ list_for_each_entry(t, &tpebs_results, nd) {
+ if (t->tpebs_name == evsel->name ||
+ !strcmp(t->tpebs_name, evsel->name) ||
+ (evsel->metric_id && !strcmp(t->tpebs_name, evsel->metric_id)))
+ return t;
+ }
+ return NULL;
+}
+
/**
* evsel__tpebs_prepare - create tpebs data structures ready for opening.
* @evsel: retire_latency evsel, all evsels on its list will be prepared.
@@ -221,16 +239,11 @@ static struct tpebs_retire_lat *tpebs_retire_lat__new(struct evsel *evsel)
static int evsel__tpebs_prepare(struct evsel *evsel)
{
struct evsel *pos;
- struct tpebs_retire_lat *tpebs_event;
-
- list_for_each_entry(tpebs_event, &tpebs_results, nd) {
- if (!strcmp(tpebs_event->tpebs_name, evsel->name)) {
- /*
- * evsel, or an identically named one, was already
- * prepared.
- */
- return 0;
- }
+ struct tpebs_retire_lat *tpebs_event = tpebs_retire_lat__find(evsel);
+
+ if (tpebs_event) {
+ /* evsel, or an identically named one, was already prepared. */
+ return 0;
}
tpebs_event = tpebs_retire_lat__new(evsel);
if (!tpebs_event)
@@ -262,12 +275,19 @@ int evsel__tpebs_open(struct evsel *evsel)
{
int ret;

- /*
- * We should only run tpebs_start when tpebs_recording is enabled.
- * And we should only run it once with all the required events.
- */
- if (tpebs_cmd.pid != 0 || !tpebs_recording)
+ /* We should only run tpebs_start when tpebs_recording is enabled. */
+ if (!tpebs_recording)
return 0;
+ /* Only start the events once. */
+ if (tpebs_cmd.pid != 0) {
+ struct tpebs_retire_lat *t = tpebs_retire_lat__find(evsel);
+
+ if (!t || !t->started) {
+ /* Fail, as the event wasn't started. */
+ return -EBUSY;
+ }
+ return 0;
+ }

ret = evsel__tpebs_prepare(evsel);
if (ret)
@@ -352,7 +372,6 @@ int evsel__tpebs_open(struct evsel *evsel)
int tpebs_set_evsel(struct evsel *evsel, int cpu_map_idx, int thread)
{
__u64 val;
- bool found = false;
struct tpebs_retire_lat *t;
struct perf_counts_values *count;

@@ -367,19 +386,13 @@ int tpebs_set_evsel(struct evsel *evsel, int cpu_map_idx, int thread)
tpebs_stop();
count = perf_counts(evsel->counts, cpu_map_idx, thread);

- list_for_each_entry(t, &tpebs_results, nd) {
- if (t->tpebs_name == evsel->name ||
- (evsel->metric_id && !strcmp(t->tpebs_name, evsel->metric_id))) {
- found = true;
- break;
- }
- }
+ t = tpebs_retire_lat__find(evsel);

/* Set ena and run to non-zero */
count->ena = count->run = 1;
count->lost = 0;

- if (!found) {
+ if (!t) {
/*
* Set default value or 0 when retire_latency for this event is
* not found from sampling data (record_tpebs not set or 0
--
2.49.0.504.g3bcea36a83-goog