Re: [PATCH v3 08/14] perf kvm: Add dimensions for KVM event statistics

[Namhyung Kim]

Hi Leo,

On Tue, Feb 28, 2023 at 3:53 AM Leo Yan <leo.yan@xxxxxxxxxx> wrote:
>
> To support KVM event statistics, this patch firstly registers histograms
> columns and sorting fields; every column or field has its own format
> structure, the format structure is dereferenced to access the dimension,
> finally the dimension provides the comparison callback for sorting
> result.
>
> Signed-off-by: Leo Yan <leo.yan@xxxxxxxxxx>
> Reviewed-by: James Clark <james.clark@xxxxxxx>
> ---
>  tools/perf/builtin-kvm.c   | 239 +++++++++++++++++++++++++++++++++++--
>  tools/perf/util/kvm-stat.h |   2 +
>  2 files changed, 234 insertions(+), 7 deletions(-)
>
> diff --git a/tools/perf/builtin-kvm.c b/tools/perf/builtin-kvm.c
> index a9f467926bdd..da84f5063d4d 100644
> --- a/tools/perf/builtin-kvm.c
> +++ b/tools/perf/builtin-kvm.c
> @@ -70,9 +70,9 @@ static int cmp_event_ ## func(struct kvm_event *one,                  \
>                get_event_ ##func(two, vcpu);                            \
>  }
>
> -GET_EVENT_KEY(time, time);
> -GET_EVENT_KEY(max, stats.max);
> -GET_EVENT_KEY(min, stats.min);
> +COMPARE_EVENT_KEY(time, time);
> +COMPARE_EVENT_KEY(max, stats.max);
> +COMPARE_EVENT_KEY(min, stats.min);
>  COMPARE_EVENT_KEY(count, stats.n);
>  COMPARE_EVENT_KEY(mean, stats.mean);
>
> @@ -90,13 +90,238 @@ struct kvm_hists {
>         struct perf_hpp_list    list;
>  };
>
> +struct kvm_dimension {
> +       const char *name;
> +       int64_t (*cmp)(struct perf_hpp_fmt *fmt, struct hist_entry *left,
> +                      struct hist_entry *right);
> +};
> +
> +struct kvm_fmt {
> +       struct perf_hpp_fmt     fmt;
> +       struct kvm_dimension    *dim;
> +};
> +
>  static struct kvm_hists kvm_hists;
>
> -static int kvm_hists__init(void)
> +static int64_t
> +empty_cmp(struct perf_hpp_fmt *fmt __maybe_unused,
> +         struct hist_entry *left __maybe_unused,
> +         struct hist_entry *right __maybe_unused)
> +{
> +       return 0;
> +}
> +
> +static struct kvm_dimension dim_event = {
> +       .name           = "name",
> +       .cmp            = empty_cmp,
> +};

I guess you can name it as 'dim_name' to reduce the confusion.
Also it can compare event names using strcmp() in case users
want to see event names in alphabetical order.

[SNIP]
> +
> +static int kvm_hists__init_output(struct perf_hpp_list *hpp_list, char *name)
> +{
> +       struct kvm_fmt *kvm_fmt = get_format(name);
> +
> +       if (!kvm_fmt) {
> +               reset_dimensions();
> +               return output_field_add(hpp_list, name);

Hmm.. do you plan to support these generic output fields too?
I'm not sure you need reset_dimensions() here.

> +       }
> +
> +       perf_hpp_list__column_register(hpp_list, &kvm_fmt->fmt);
> +       return 0;
> +}
> +
> +static int kvm_hists__init_sort(struct perf_hpp_list *hpp_list, char *name)
> +{
> +       struct kvm_fmt *kvm_fmt = get_format(name);
> +
> +       if (!kvm_fmt) {
> +               reset_dimensions();
> +               return sort_dimension__add(hpp_list, name, NULL, 0);

Ditto.

> +       }
> +
> +       perf_hpp_list__register_sort_field(hpp_list, &kvm_fmt->fmt);
> +       return 0;
> +}
> +
> +static int kvm_hpp_list__init(char *list,
> +                             struct perf_hpp_list *hpp_list,
> +                             int (*fn)(struct perf_hpp_list *hpp_list,
> +                                       char *name))
> +{
> +       char *tmp, *tok;
> +       int ret;
> +
> +       if (!list || !fn)
> +               return 0;
> +
> +       for (tok = strtok_r(list, ", ", &tmp); tok;
> +            tok = strtok_r(NULL, ", ", &tmp)) {
> +               ret = fn(hpp_list, tok);
> +               if (!ret)
> +                       continue;
> +
> +               /* Handle errors */
> +               if (ret == -EINVAL)
> +                       pr_err("Invalid field key: '%s'", tok);
> +               else if (ret == -ESRCH)
> +                       pr_err("Unknown field key: '%s'", tok);
> +               else
> +                       pr_err("Fail to initialize for field key: '%s'", tok);
> +
> +               break;
> +       }
> +
> +       return ret;
> +}
> +
> +static int kvm_hpp_list__parse(struct perf_hpp_list *hpp_list,
> +                              const char *output_, const char *sort_)
> +{
> +       char *output = output_ ? strdup(output_) : NULL;
> +       char *sort = sort_ ? strdup(sort_) : NULL;
> +       int ret;
> +
> +       ret = kvm_hpp_list__init(output, hpp_list, kvm_hists__init_output);
> +       if (ret)
> +               goto out;
> +
> +       ret = kvm_hpp_list__init(sort, hpp_list, kvm_hists__init_sort);
> +       if (ret)
> +               goto out;
> +
> +       /* Copy sort keys to output fields */
> +       perf_hpp__setup_output_field(hpp_list);

I think you also need perf_hpp__append_sort_keys() as in
setup_sorting() to have secondary sort keys in case the
given sort key cannot determine the ordering.

Thanks,
Namhyung


> +
> +out:
> +       free(output);
> +       free(sort);
> +       return ret;
> +}
> +
> +static int kvm_hists__init(struct perf_kvm_stat *kvm)
> +{
> +       const char *output_columns = "name,sample,time,max_t,min_t,mean_t";
> +
>         __hists__init(&kvm_hists.hists, &kvm_hists.list);
>         perf_hpp_list__init(&kvm_hists.list);
> -       return 0;
> +       return kvm_hpp_list__parse(&kvm_hists.list, output_columns,
> +                                  kvm->sort_key);
>  }
>
>  static const char *get_filename_for_perf_kvm(void)
> @@ -979,7 +1204,7 @@ static int kvm_events_live_report(struct perf_kvm_stat *kvm)
>         set_term_quiet_input(&save);
>         init_kvm_event_record(kvm);
>
> -       kvm_hists__init();
> +       kvm_hists__init(kvm);
>
>         signal(SIGINT, sig_handler);
>         signal(SIGTERM, sig_handler);
> @@ -1176,7 +1401,7 @@ static int kvm_events_report_vcpu(struct perf_kvm_stat *kvm)
>         init_kvm_event_record(kvm);
>         setup_pager();
>
> -       kvm_hists__init();
> +       kvm_hists__init(kvm);
>
>         ret = read_events(kvm);
>         if (ret)
> diff --git a/tools/perf/util/kvm-stat.h b/tools/perf/util/kvm-stat.h
> index 80d5c5a9ae31..ca5796959f66 100644
> --- a/tools/perf/util/kvm-stat.h
> +++ b/tools/perf/util/kvm-stat.h
> @@ -40,6 +40,8 @@ struct kvm_event {
>         #define DEFAULT_VCPU_NUM 8
>         int max_vcpu;
>         struct kvm_event_stats *vcpu;
> +
> +       struct hist_entry he;
>  };
>
>  typedef int (*key_cmp_fun)(struct kvm_event*, struct kvm_event*, int);
> --
> 2.34.1
>