linux-kernel - Re: [PATCH v5 1/5] perf metric: Event "Compat" value supports matching multiple identifiers

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Message-ID: <268b3891-be4b-5f63-eff3-7b6d83e906e9@oracle.com>
Date:   Fri, 28 Jul 2023 09:11:01 +0100
From:   John Garry <john.g.garry@...cle.com>
To:     Jing Zhang <renyu.zj@...ux.alibaba.com>,
        Ian Rogers <irogers@...gle.com>
Cc:     Will Deacon <will@...nel.org>, Mark Rutland <mark.rutland@....com>,
        Robin Murphy <robin.murphy@....com>,
        Ilkka Koskinen <ilkka@...amperecomputing.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-perf-users@...r.kernel.org, linux-doc@...r.kernel.org,
        Zhuo Song <zhuo.song@...ux.alibaba.com>,
        Shuai Xue <xueshuai@...ux.alibaba.com>
Subject: Re: [PATCH v5 1/5] perf metric: Event "Compat" value supports
 matching multiple identifiers

On 28/07/2023 07:17, Jing Zhang wrote:
> The jevent "Compat" is used for uncore PMU alias or metric definitions.
> 
> The same PMU driver has different PMU identifiers due to different hardware
> versions and types, but they may have some common PMU event/metric. Since a
> Compat value can only match one identifier, when adding the same event
> alias and metric to PMUs with different identifiers, each identifier needs
> to be defined once, which is not streamlined enough.
> 
> So let "Compat" value supports matching multiple identifiers. For example,
> the Compat value {abcde;123*}
why not use a comma-separated list? that is more common

> can match the PMU identifier "abcde" and the
> the PMU identifier with the prefix "123",

I have to admit that this is not a great example as it does not match an 
expected real-life scenario. I mean, I would not expect a PMU identifier 
for the same PMU to be in either format "abcde" or "123*". I would 
expect to be in only ever one format.

> where "*" is a wildcard.
> Tokens in Unit field are delimited by ';' with no spaces.
> 
> Signed-off-by: Jing Zhang <renyu.zj@...ux.alibaba.com>
> ---
>   tools/perf/util/metricgroup.c |  2 +-
>   tools/perf/util/pmu.c         | 27 ++++++++++++++++++++++++++-
>   tools/perf/util/pmu.h         |  1 +
>   3 files changed, 28 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
> index 5e9c657..ff81bc5 100644
> --- a/tools/perf/util/metricgroup.c
> +++ b/tools/perf/util/metricgroup.c
> @@ -477,7 +477,7 @@ static int metricgroup__sys_event_iter(const struct pmu_metric *pm,
>   
>   	while ((pmu = perf_pmu__scan(pmu))) {
>   
> -		if (!pmu->id || strcmp(pmu->id, pm->compat))
> +		if (!pmu->id || !pmu_uncore_identifier_match(pmu->id, pm->compat))
>   			continue;
>   
>   		return d->fn(pm, table, d->data);
> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index ad209c8..3ae249b 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -776,6 +776,31 @@ static bool pmu_uncore_alias_match(const char *pmu_name, const char *name)
>   	return res;
>   }
>   
> +bool pmu_uncore_identifier_match(const char *id, const char *compat)
> +{
> +	char *tmp = NULL, *tok, *str;
> +	bool res;
> +	int n;
> +
> +	str = strdup(compat);

why duplicate this? are you modifying something?

> +	if (!str)
> +		return false;
> +
> +	tok = strtok_r(str, ";", &tmp);
> +	for (; tok; tok = strtok_r(NULL, ";", &tmp)) {
> +		n = strlen(tok);
> +		if ((tok[n - 1] == '*' && !strncmp(id, tok, n - 1)) ||
> +		    !strcmp(id, tok)) {
> +			res = true;
> +			goto out;
> +		}
> +	}
> +	res = false;
> +out:
> +	free(str);
> +	return res;
> +}
> +
>   struct pmu_add_cpu_aliases_map_data {
>   	struct list_head *head;
>   	const char *name;
> @@ -847,7 +872,7 @@ static int pmu_add_sys_aliases_iter_fn(const struct pmu_event *pe,

This is not for metrics specifically. You are really doing 2x things 
here. I suggest that you split the patch out into 1st pmu.c change and 
2nd metricgroup.c change

>   	if (!pe->compat || !pe->pmu)
>   		return 0;
>   
> -	if (!strcmp(pmu->id, pe->compat) &&
> +	if (pmu_uncore_identifier_match(pmu->id, pe->compat) &&
>   	    pmu_uncore_alias_match(pe->pmu, pmu->name)) {

nit: let's change order to check alias and then identifier

>   		__perf_pmu__new_alias(idata->head, -1,
>   				      (char *)pe->name,
> diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
> index b9a02de..9d4385d 100644
> --- a/tools/perf/util/pmu.h
> +++ b/tools/perf/util/pmu.h
> @@ -241,6 +241,7 @@ void pmu_add_cpu_aliases_table(struct list_head *head, struct perf_pmu *pmu,
>   char *perf_pmu__getcpuid(struct perf_pmu *pmu);
>   const struct pmu_events_table *pmu_events_table__find(void);
>   const struct pmu_metrics_table *pmu_metrics_table__find(void);
> +bool pmu_uncore_identifier_match(const char *id, const char *compat);
>   void perf_pmu_free_alias(struct perf_pmu_alias *alias);
>   
>   int perf_pmu__convert_scale(const char *scale, char **end, double *sval);

Thanks,
John