linux-kernel - Re: [PATCH 11/18] perf metric: Add referenced metrics to hash data

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Date:   Wed, 15 Jul 2020 23:36:09 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     Ian Rogers <irogers@...gle.com>
Cc:     Jiri Olsa <jolsa@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Michael Petlan <mpetlan@...hat.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Kajol Jain <kjain@...ux.ibm.com>,
        John Garry <john.garry@...wei.com>,
        "Paul A. Clarke" <pc@...ibm.com>,
        Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH 11/18] perf metric: Add referenced metrics to hash data

On Wed, Jul 15, 2020 at 11:25:14AM -0700, Ian Rogers wrote:
> On Sun, Jul 12, 2020 at 6:27 AM Jiri Olsa <jolsa@...nel.org> wrote:

SNIP

> > +int expr__add_ref(struct expr_parse_ctx *ctx, struct metric_ref *ref)
> > +{
> > +       struct expr_id_data *data_ptr = NULL, *old_data = NULL;
> > +       char *old_key = NULL;
> > +       char *name;
> > +       int ret;
> > +
> > +       data_ptr = zalloc(sizeof(*data_ptr));
> > +       if (!data_ptr)
> > +               return -ENOMEM;
> > +
> > +       name = strdup(ref->metric_name);
> > +       if (!name) {
> > +               free(data_ptr);
> > +               return -ENOMEM;
> > +       }
> > +
> > +       data_ptr->ref.metric_name = ref->metric_name;
> > +       data_ptr->ref.metric_expr = ref->metric_expr;
> 
> Having one owned string and one unowned makes the memory management
> here somewhat complicated. Perhaps dupe both?

right, will check on this

> 
> > +       data_ptr->is_ref = true;
> > +
> > +       ret = hashmap__set(&ctx->ids, name, data_ptr,
> > +                          (const void **)&old_key, (void **)&old_data);
> > +
> > +       pr_debug2("adding ref metric %s: %s\n",
> > +                 ref->metric_name, ref->metric_expr);
> > +
> > +       free(old_key);
> > +       free(old_data);
> > +       return ret;
> > +}
> > +
> >  int expr__get_id(struct expr_parse_ctx *ctx, const char *id,
> >                  struct expr_id_data **data)
> >  {
> > diff --git a/tools/perf/util/expr.h b/tools/perf/util/expr.h
> > index 2462abd0ac65..d19e66915228 100644
> > --- a/tools/perf/util/expr.h
> > +++ b/tools/perf/util/expr.h
> > @@ -11,12 +11,22 @@
> >  #include "util/hashmap.h"
> >  //#endif
> >
> > +struct metric_ref;
> > +
> >  struct expr_parse_ctx {
> >         struct hashmap ids;
> >  };
> >
> >  struct expr_id_data {
> > -       double  val;
> > +       bool    is_ref;
> 
> nit: place at the end to avoid padding?

ok

> 
> > +
> > +       union {
> > +               double  val;
> > +               struct {
> > +                       const char *metric_name;
> > +                       const char *metric_expr;
> > +               } ref;
> > +       };
> >  };
> >
> >  struct expr_scanner_ctx {
> > @@ -29,6 +39,7 @@ void expr__ctx_clear(struct expr_parse_ctx *ctx);
> >  void expr__del_id(struct expr_parse_ctx *ctx, const char *id);
> >  int expr__add_id(struct expr_parse_ctx *ctx, const char *id);
> >  int expr__add_id_val(struct expr_parse_ctx *ctx, const char *id, double val);
> > +int expr__add_ref(struct expr_parse_ctx *ctx, struct metric_ref *ref);
> >  int expr__get_id(struct expr_parse_ctx *ctx, const char *id,
> >                  struct expr_id_data **data);
> >  int expr__parse(double *final_val, struct expr_parse_ctx *ctx,
> > diff --git a/tools/perf/util/stat-shadow.c b/tools/perf/util/stat-shadow.c
> > index fc9ac4b4218e..e1ba6c1b916a 100644
> > --- a/tools/perf/util/stat-shadow.c
> > +++ b/tools/perf/util/stat-shadow.c
> > @@ -731,13 +731,14 @@ static void print_smi_cost(struct perf_stat_config *config,
> >  }
> >
> >  static int prepare_metric(struct evsel **metric_events,
> > +                         struct metric_ref *metric_refs,
> 
> nit: the plural on refs confused me at first, perhaps a comment that
> this is the array of referenced metrics.

I'll add the comment

thanks,
jirka