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

Ian Rogers
2025-04-07T20:08:01Z

On Mon, Apr 7, 2025 at 12:37 PM Liang, Kan <kan.liang@linux.intel.com> wrote:
>
>
>
> 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, I also use it for the (unmerged) DRM PMU:
https://lore.kernel.org/lkml/20250403202439.57791-4-irogers@google.com/
I think adding a common function for this can be follow up work.

Thanks,
Ian

> 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 */
>