Re: [RFC PATCH v3 13/18] perf stat: Handle taken alone in hardware-grouping

[Ian Rogers]

On Tue, Dec 12, 2023 at 3:03 PM <weilin.wang@xxxxxxxxx> wrote:
>
> From: Weilin Wang <weilin.wang@xxxxxxxxx>
>
> Add taken alone into consideration when grouping. Only one taken
> alone event is supported per group.

This seems to be a deficiency also in parse_events__sort_events_and_fix_groups:
https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/util/parse-events.c?h=perf-tools-next#n2025
Is there an example of events that must be taken alone? Perhaps
because they share a fixed counter?

Thanks,
Ian

> Signed-off-by: Weilin Wang <weilin.wang@xxxxxxxxx>
> ---
>  tools/perf/pmu-events/jevents.py   |  7 +++++--
>  tools/perf/pmu-events/pmu-events.h |  1 +
>  tools/perf/util/metricgroup.c      | 18 +++++++++++++-----
>  tools/perf/util/metricgroup.h      |  2 ++
>  4 files changed, 21 insertions(+), 7 deletions(-)
>
> diff --git a/tools/perf/pmu-events/jevents.py b/tools/perf/pmu-events/jevents.py
> index 16f17d335f8e..e5919e5e6d4a 100755
> --- a/tools/perf/pmu-events/jevents.py
> +++ b/tools/perf/pmu-events/jevents.py
> @@ -55,7 +55,9 @@ _json_event_attributes = [
>      # Counter this event could use
>      'counter',
>      # Longer things (the last won't be iterated over during decompress).
> -    'long_desc'
> +    'long_desc',
> +    # Taken alone event could not be collected in the same group with other taken alone event
> +    'taken_alone'
>  ]
>
>  # Attributes that are in pmu_unit_layout.
> @@ -71,7 +73,7 @@ _json_metric_attributes = [
>  ]
>  # Attributes that are bools or enum int values, encoded as '0', '1',...
>  _json_enum_attributes = ['aggr_mode', 'deprecated', 'event_grouping', 'perpkg',
> -    'size', 'fixed_size'
> +    'size', 'fixed_size', 'taken_alone'
>  ]
>
>  def removesuffix(s: str, suffix: str) -> str:
> @@ -331,6 +333,7 @@ class JsonEvent:
>        extra_desc += '  Spec update: ' + jd['Errata']
>      self.pmu = unit_to_pmu(jd.get('Unit'))
>      self.counter = jd.get('Counter')
> +    self.taken_alone = jd.get('TakenAlone')
>      self.size = jd.get('Size')
>      self.fixed_size = jd.get('FixedSize')
>      filter = jd.get('Filter')
> diff --git a/tools/perf/pmu-events/pmu-events.h b/tools/perf/pmu-events/pmu-events.h
> index 65e0c5dd8bb4..ce10356e9665 100644
> --- a/tools/perf/pmu-events/pmu-events.h
> +++ b/tools/perf/pmu-events/pmu-events.h
> @@ -50,6 +50,7 @@ struct pmu_event {
>         const char *unit;
>         bool perpkg;
>         bool deprecated;
> +       bool taken_alone;
>  };
>
>  struct pmu_metric {
> diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
> index 016ea949ba5d..78e607f3ad56 100644
> --- a/tools/perf/util/metricgroup.c
> +++ b/tools/perf/util/metricgroup.c
> @@ -1624,6 +1624,7 @@ static void metricgroup__free_pmu_info(struct list_head *pmu_info_list)
>  static struct metricgroup__event_info *event_info__new(const char *name,
>                                                       const char *pmu_name,
>                                                       const char *counter,
> +                                                     bool taken_alone,
>                                                       bool free_counter)
>  {
>         int ret = 0;
> @@ -1638,6 +1639,7 @@ static struct metricgroup__event_info *event_info__new(const char *name,
>                 pmu_name = "core";
>
>         e->name = name;
> +       e->taken_alone = taken_alone;
>         e->free_counter = free_counter;
>         e->pmu_name = pmu_name;
>         if (free_counter) {
> @@ -1676,7 +1678,8 @@ static int metricgroup__add_metric_event_callback(const struct pmu_event *pe,
>         if (!strcasecmp(pe->name, d->event_name)) {
>                 if (!pe->counter)
>                         return -EINVAL;
> -               event = event_info__new(d->event_id, pe->pmu, pe->counter, /*free_counter=*/false);
> +               event = event_info__new(d->event_id, pe->pmu, pe->counter,
> +                                       pe->taken_alone, /*free_counter=*/false);
>                 if (!event)
>                         return -ENOMEM;
>                 list_add(&event->nd, d->list);
> @@ -1799,6 +1802,8 @@ static int find_and_set_counters(struct metricgroup__event_info *e,
>         int ret;
>         unsigned long find_bit = 0;
>
> +       if (e->taken_alone && current_group->taken_alone)
> +               return -ENOSPC;
>         if (e->free_counter)
>                 return 0;
>         if (e->fixed_counter) {
> @@ -1833,11 +1838,13 @@ static int _insert_event(struct metricgroup__event_info *e,
>                 list_add(&event->nd, &group->event_head);
>         else
>                 list_add_tail(&event->nd, &group->event_head);
> +       if (e->taken_alone)
> +               group->taken_alone = true;
>         return 0;
>  }
>
>  /**
> - * Insert the new_group node at the end of the group list.
> + * Initialize the new group and insert it to the end of the group list.
>   */
>  static int insert_new_group(struct list_head *head,
>                            struct metricgroup__group *new_group,
> @@ -1847,6 +1854,7 @@ static int insert_new_group(struct list_head *head,
>         INIT_LIST_HEAD(&new_group->event_head);
>         fill_counter_bitmap(new_group->gp_counters, 0, size);
>         fill_counter_bitmap(new_group->fixed_counters, 0, fixed_size);
> +       new_group->taken_alone = false;
>         list_add_tail(&new_group->nd, head);
>         return 0;
>  }
> @@ -2050,8 +2058,8 @@ static int create_grouping(struct list_head *pmu_info_list,
>         //TODO: for each new core group, we should consider to add events that uses fixed counters
>         list_for_each_entry(e, event_info_list, nd) {
>                 bitmap_scnprintf(e->counters, NR_COUNTERS, bit_buf, NR_COUNTERS);
> -               pr_debug("Event name %s, [pmu]=%s, [counters]=%s\n", e->name,
> -                       e->pmu_name, bit_buf);
> +               pr_debug("Event name %s, [pmu]=%s, [counters]=%s, [taken_alone]=%d\n",
> +                       e->name, e->pmu_name, bit_buf, e->taken_alone);
>                 ret = assign_event_grouping(e, pmu_info_list, &groups);
>                 if (ret)
>                         goto out;
> @@ -2098,7 +2106,7 @@ static int hw_aware_build_grouping(struct expr_parse_ctx *ctx __maybe_unused,
>                 if (is_special_event(id)) {
>                         struct metricgroup__event_info *event;
>
> -                       event = event_info__new(id, "default_core", "0",
> +                       event = event_info__new(id, "default_core", "0", false,
>                                                 /*free_counter=*/true);
>                         if (!event)
>                                 goto err_out;
> diff --git a/tools/perf/util/metricgroup.h b/tools/perf/util/metricgroup.h
> index 37fdf8c5ba77..8f6a1bb9d1ad 100644
> --- a/tools/perf/util/metricgroup.h
> +++ b/tools/perf/util/metricgroup.h
> @@ -105,6 +105,7 @@ struct metricgroup__event_info {
>         const char *pmu_name;
>         bool fixed_counter;
>         bool free_counter;
> +       bool taken_alone;
>         /** The counters the event allowed to be collected on. */
>         DECLARE_BITMAP(counters, NR_COUNTERS);
>  };
> @@ -154,6 +155,7 @@ struct metricgroup__group {
>         DECLARE_BITMAP(fixed_counters, NR_COUNTERS);
>         /** Head to the list of event names in this group*/
>         struct list_head event_head;
> +       bool taken_alone;
>  };
>
>  struct metricgroup__group_events {
> --
> 2.39.3
>