linux-kernel - Re: [RFC PATCH v3 13/14] perf metricgroup: remove duped metric group events

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Date:   Fri, 8 May 2020 17:38:30 -0700
From:   Andi Kleen <ak@...ux.intel.com>
To:     Ian Rogers <irogers@...gle.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Martin KaFai Lau <kafai@...com>,
        Song Liu <songliubraving@...com>, Yonghong Song <yhs@...com>,
        Andrii Nakryiko <andriin@...com>,
        John Fastabend <john.fastabend@...il.com>,
        KP Singh <kpsingh@...omium.org>,
        Kajol Jain <kjain@...ux.ibm.com>,
        John Garry <john.garry@...wei.com>,
        Jin Yao <yao.jin@...ux.intel.com>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Kim Phillips <kim.phillips@....com>,
        linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        bpf@...r.kernel.org, linux-perf-users@...r.kernel.org,
        Vince Weaver <vincent.weaver@...ne.edu>,
        Stephane Eranian <eranian@...gle.com>
Subject: Re: [RFC PATCH v3 13/14] perf metricgroup: remove duped metric group
 events

>  static struct evsel *find_evsel_group(struct evlist *perf_evlist,
>  				      struct expr_parse_ctx *pctx,
> +				      bool has_constraint,
>  				      struct evsel **metric_events,
>  				      unsigned long *evlist_used)
>  {
> -	struct evsel *ev;
> -	bool leader_found;
> -	const size_t idnum = hashmap__size(&pctx->ids);
> -	size_t i = 0;
> -	int j = 0;
> +	struct evsel *ev, *current_leader = NULL;
>  	double *val_ptr;
> +	int i = 0, matched_events = 0, events_to_match;
> +	const int idnum = (int)hashmap__size(&pctx->ids);

BTW standard perf data structure would be a rblist or strlist

I think it would be really better to do the deduping in a separate
pass than trying to add it to find_evsel_group. This leads
to very complicated logic.

This will likely make it easier to implement more sophisticated
algorithms too.

-Andi