Sender: Namhyung Kim <namhyung@gmail.com>
Date:   Fri, 24 Feb 2023 14:48:07 -0800
From:   Namhyung Kim <namhyung@kernel.org>
To:     Ian Rogers <irogers@google.com>
Cc:     Peter Zijlstra <peterz@infradead.org>,
        Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Maxime Coquelin <mcoquelin.stm32@gmail.com>,
        Alexandre Torgue <alexandre.torgue@foss.st.com>,
        Zhengjun Xing <zhengjun.xing@linux.intel.com>,
        Sandipan Das <sandipan.das@amd.com>,
        James Clark <james.clark@arm.com>,
        Kajol Jain <kjain@linux.ibm.com>,
        John Garry <john.g.garry@oracle.com>,
        Kan Liang <kan.liang@linux.intel.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Andrii Nakryiko <andrii@kernel.org>,
        Eduard Zingerman <eddyz87@gmail.com>,
        Suzuki Poulouse <suzuki.poulose@arm.com>,
        Leo Yan <leo.yan@linaro.org>,
        Florian Fischer <florian.fischer@muhq.space>,
        Ravi Bangoria <ravi.bangoria@amd.com>,
        Jing Zhang <renyu.zj@linux.alibaba.com>,
        Sean Christopherson <seanjc@google.com>,
        Athira Rajeev <atrajeev@linux.vnet.ibm.com>,
        linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org,
        linux-stm32@st-md-mailman.stormreply.com,
        linux-arm-kernel@lists.infradead.org,
        Perry Taylor <perry.taylor@intel.com>,
        Caleb Biggers <caleb.biggers@intel.com>,
        Stephane Eranian <eranian@google.com>
Subject: Re: [PATCH v1 50/51] perf stat: Use counts rather than saved_value
Message-ID: <Y/k+p8IPY/ftl3KQ@google.com>
References: <20230219092848.639226-1-irogers@google.com>
 <20230219092848.639226-51-irogers@google.com>
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On Sun, Feb 19, 2023 at 01:28:47AM -0800, Ian Rogers wrote:
> Switch the hard coded metrics to use the aggregate value rather than
> from saved_value. When computing a metric like IPC the aggregate count
> comes from instructions then cycles is looked up and if present IPC
> computed. Rather than lookup from the saved_value rbtree, search the
> counter's evlist for the desired counter.
> 
> A new helper evsel__stat_type is used to both quickly find a metric
> function and to identify when a counter is the one being sought. So
> that both total and miss counts can be sought, the stat_type enum is
> expanded. The ratio functions are rewritten to share a common helper
> with the ratios being directly passed rather than computed from an
> enum value.
> 
> Signed-off-by: Ian Rogers <irogers@google.com>
> ---
[SNIP]
> -static double runtime_stat_avg(enum stat_type type, int aggr_idx,
> -			       struct runtime_stat_data *rsd)
> +static double find_stat(const struct evsel *evsel, int aggr_idx, enum stat_type type)
>  {
> -	struct saved_value *v;
> -
> -	v = saved_value_lookup(NULL, aggr_idx, false, type, rsd->ctx, rsd->cgrp);
> -	if (!v)
> -		return 0.0;
> -
> -	return avg_stats(&v->stats);
> +	const struct evsel *cur;
> +	int evsel_ctx = evsel_context(evsel);
> +
> +	evlist__for_each_entry(evsel->evlist, cur) {
> +		struct perf_stat_aggr *aggr;
> +
> +		/* Ignore the evsel that is being searched from. */
> +		if (evsel == cur)
> +			continue;
> +
> +		/* Ignore evsels that are part of different groups. */
> +		if (evsel->core.leader->nr_members &&
> +		    evsel->core.leader != cur->core.leader)

The evsel->nr_members is somewhat confusing in that it counts itself
as a member.  I'm not sure it resets the nr_members to 0 for standalone
events.  You'd better checking nr_members greater than 1 for group
events.

Thanks,
Namhyung


> +			continue;
> +		/* Ignore evsels with mismatched modifiers. */
> +		if (evsel_ctx != evsel_context(cur))
> +			continue;
> +		/* Ignore if not the cgroup we're looking for. */
> +		if (evsel->cgrp != cur->cgrp)
> +			continue;
> +		/* Ignore if not the stat we're looking for. */
> +		if (type != evsel__stat_type(cur))
> +			continue;
> +
> +		aggr = &cur->stats->aggr[aggr_idx];
> +		if (type == STAT_NSECS)
> +			return aggr->counts.val;
> +		return aggr->counts.val * cur->scale;
> +	}
> +	return 0.0;
>  }