Re: [PATCH v2 10/16] perf intel-tpebs: Add support for updating counts in evsel__tpebs_read

Liang, Kan
2025-04-07T19:37:13Z

On 2025-04-07 1:00 a.m., Ian Rogers wrote:
> Rename to reflect evsel argument and for consistency with other tpebs
> functions. Update count from prev_raw_counts when
> available. Eventually this will allow inteval mode support.
>
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
> tools/perf/util/evsel.c | 11 ++------
> tools/perf/util/intel-tpebs.c | 52 ++++++++++++++---------------------
> tools/perf/util/intel-tpebs.h | 2 +-
> 3 files changed, 25 insertions(+), 40 deletions(-)
>
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index 554252ed1aab..1d343f51225b 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -1718,11 +1718,6 @@ static int evsel__read_one(struct evsel *evsel, int cpu_map_idx, int thread)
> return perf_evsel__read(&evsel->core, cpu_map_idx, thread, count);
> }
>
> -static int evsel__read_retire_lat(struct evsel *evsel, int cpu_map_idx, int thread)
> -{
> - return tpebs_set_evsel(evsel, cpu_map_idx, thread);
> -}
> -
> static void evsel__set_count(struct evsel *counter, int cpu_map_idx, int thread,
> u64 val, u64 ena, u64 run, u64 lost)
> {
> @@ -1730,8 +1725,8 @@ static void evsel__set_count(struct evsel *counter, int cpu_map_idx, int thread,
>
> count = perf_counts(counter->counts, cpu_map_idx, thread);
>
> - if (counter->retire_lat) {
> - evsel__read_retire_lat(counter, cpu_map_idx, thread);
> + if (evsel__is_retire_lat(counter)) {
> + evsel__tpebs_read(counter, cpu_map_idx, thread);
> perf_counts__set_loaded(counter->counts, cpu_map_idx, thread, true);
> return;
> }
> @@ -1889,7 +1884,7 @@ int evsel__read_counter(struct evsel *evsel, int cpu_map_idx, int thread)
> return evsel__hwmon_pmu_read(evsel, cpu_map_idx, thread);
>
> if (evsel__is_retire_lat(evsel))
> - return evsel__read_retire_lat(evsel, cpu_map_idx, thread);
> + return evsel__tpebs_read(evsel, cpu_map_idx, thread);
>
> if (evsel->core.attr.read_format & PERF_FORMAT_GROUP)
> return evsel__read_group(evsel, cpu_map_idx, thread);
> diff --git a/tools/perf/util/intel-tpebs.c b/tools/perf/util/intel-tpebs.c
> index e3227646a9cc..452ce3698221 100644
> --- a/tools/perf/util/intel-tpebs.c
> +++ b/tools/perf/util/intel-tpebs.c
> @@ -415,49 +415,39 @@ int evsel__tpebs_open(struct evsel *evsel)
> return ret;
> }
>
> -
> -int tpebs_set_evsel(struct evsel *evsel, int cpu_map_idx, int thread)
> +int evsel__tpebs_read(struct evsel *evsel, int cpu_map_idx, int thread)
> {
> - __u64 val;
> + struct perf_counts_values *count, *old_count = NULL;
> struct tpebs_retire_lat *t;
> - struct perf_counts_values *count;
> + uint64_t val;
> +
> + /* Only set retire_latency value to the first CPU and thread. */
> + if (cpu_map_idx != 0 || thread != 0)
> + return 0;
> +
> + if (evsel->prev_raw_counts)
> + old_count = perf_counts(evsel->prev_raw_counts, cpu_map_idx, thread);
>
> - /* Non reitre_latency evsel should never enter this function. */
> - if (!evsel__is_retire_lat(evsel))
> - return -1;
> + count = perf_counts(evsel->counts, cpu_map_idx, thread);
>
> /*
> * Need to stop the forked record to ensure get sampled data from the
> * PIPE to process and get non-zero retire_lat value for hybrid.
> */
> tpebs_stop();
> - count = perf_counts(evsel->counts, cpu_map_idx, thread);
>
> t = tpebs_retire_lat__find(evsel);
> -
> - /* Set ena and run to non-zero */
> - count->ena = count->run = 1;
> - count->lost = 0;
> -
> - 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
> - * sample recorded).
> - */
> - count->val = 0;
> - return 0;
> + val = rint(t->val);
> +
> + if (old_count) {
> + count->val = old_count->val + val;
> + count->run = old_count->run + 1;
> + count->ena = old_count->ena + 1;
> + } else {
> + count->val = val;
> + count->run++;
> + count->ena++;
> }

It seems utilizing the prev_raw_counts has been used in other place,
e.g., hwmon_pmu. Is it possible to factor out a common function for it?

Thanks,
Kan> -
> - /*
> - * Only set retire_latency value to the first CPU and thread.
> - */
> - if (cpu_map_idx == 0 && thread == 0)
> - val = rint(t->val);
> - else
> - val = 0;
> -
> - count->val = val;
> return 0;
> }
>
> diff --git a/tools/perf/util/intel-tpebs.h b/tools/perf/util/intel-tpebs.h
> index 5c671181ec60..218a82866cee 100644
> --- a/tools/perf/util/intel-tpebs.h
> +++ b/tools/perf/util/intel-tpebs.h
> @@ -12,6 +12,6 @@ extern bool tpebs_recording;
>
> int evsel__tpebs_open(struct evsel *evsel);
> void evsel__tpebs_close(struct evsel *evsel);
> -int tpebs_set_evsel(struct evsel *evsel, int cpu_map_idx, int thread);
> +int evsel__tpebs_read(struct evsel *evsel, int cpu_map_idx, int thread);
>
> #endif /* __INTEL_TPEBS_H */