linux-kernel - Re: [PATCH v3 1/4] perf pmu: Support more complex PMU event aliasing

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Message-ID: <20190702190724.GM15462@kernel.org>
Date:   Tue, 2 Jul 2019 16:07:24 -0300
From:   Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
To:     John Garry <john.garry@...wei.com>
Cc:     peterz@...radead.org, mingo@...hat.com,
        alexander.shishkin@...ux.intel.com, jolsa@...hat.com,
        namhyung@...nel.org, tmricht@...ux.ibm.com,
        brueckner@...ux.ibm.com, kan.liang@...ux.intel.com,
        ben@...adent.org.uk, mathieu.poirier@...aro.org,
        mark.rutland@....com, will.deacon@....com,
        linux-kernel@...r.kernel.org, linuxarm@...wei.com,
        linux-arm-kernel@...ts.infradead.org, zhangshaokun@...ilicon.com,
        ak@...ux.intel.com
Subject: Re: [PATCH v3 1/4] perf pmu: Support more complex PMU event aliasing

Em Fri, Jun 28, 2019 at 10:35:49PM +0800, John Garry escreveu:
> The jevent "Unit" field is used for uncore PMU alias definition.
> 
> The form uncore_pmu_example_X is supported, where "X" is a wildcard,
> to support multiple instances of the same PMU in a system.
> 
> Unfortunately this format not suitable for all uncore PMUs; take the Hisi
> DDRC uncore PMU for example, where the name is in the form
> hisi_scclX_ddrcY.
> 
> For for current jevent parsing, we would be required to hardcode an uncore
> alias translation for each possible value of X. This is not scalable.
> 
> Instead, add support for "Unit" field in the form "hisi_sccl,ddrc", where
> we can match by hisi_scclX and ddrcY. Tokens  in Unit field
> are delimited by ','.
> 
> Signed-off-by: John Garry <john.garry@...wei.com>
> ---
>  tools/perf/util/pmu.c | 46 ++++++++++++++++++++++++++++++++++++++-----
>  1 file changed, 41 insertions(+), 5 deletions(-)
> 
> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
> index 7e7299fee550..cfc916819c59 100644
> --- a/tools/perf/util/pmu.c
> +++ b/tools/perf/util/pmu.c
> @@ -700,6 +700,46 @@ struct pmu_events_map *perf_pmu__find_map(struct perf_pmu *pmu)
>  	return map;
>  }
>  
> +static bool pmu_uncore_alias_match(const char *pmu_name, const char *name)
> +{
> +	char *tmp, *tok, *str;
> +	bool res;
> +
> +	str = strdup(pmu_name);
> +	if (!str)
> +		return false;
> +
> +	/*
> +	 * uncore alias may be from different PMU with common prefix
> +	 */
> +	tok = strtok_r(str, ",", &tmp);

In some places, e.g. gcc version 4.1.2:

  CC       /tmp/build/perf/util/pmu.o
cc1: warnings being treated as errors
util/pmu.c: In function ‘pmu_lookup’:
util/pmu.c:706: warning: ‘tmp’ may be used uninitialized in this function
mv: cannot stat `/tmp/build/perf/util/.pmu.o.tmp': No such file or directory

This silences it, adding.

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 913633ae0bf8..55f4de6442e3 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -703,7 +703,7 @@ struct pmu_events_map *perf_pmu__find_map(struct perf_pmu *pmu)
 
 static bool pmu_uncore_alias_match(const char *pmu_name, const char *name)
 {
-	char *tmp, *tok, *str;
+	char *tmp = NULL, *tok, *str;
 	bool res;
 
 	str = strdup(pmu_name);


> +	if (strncmp(pmu_name, tok, strlen(tok))) {
> +		res = false;
> +		goto out;
> +	}
> +
> +	/*
> +	 * Match more complex aliases where the alias name is a comma-delimited
> +	 * list of tokens, orderly contained in the matching PMU name.
> +	 *
> +	 * Example: For alias "socket,pmuname" and PMU "socketX_pmunameY", we
> +	 *	    match "socket" in "socketX_pmunameY" and then "pmuname" in
> +	 *	    "pmunameY".
> +	 */
> +	for (; tok; name += strlen(tok), tok = strtok_r(NULL, ",", &tmp)) {
> +		name = strstr(name, tok);
> +		if (!name) {
> +			res = false;
> +			goto out;
> +		}
> +	}
> +
> +	res = true;
> +out:
> +	free(str);
> +	return res;
> +}
> +
>  /*
>   * From the pmu_events_map, find the table of PMU events that corresponds
>   * to the current running CPU. Then, add all PMU events from that table
> @@ -730,12 +770,8 @@ static void pmu_add_cpu_aliases(struct list_head *head, struct perf_pmu *pmu)
>  			break;
>  		}
>  
> -		/*
> -		 * uncore alias may be from different PMU
> -		 * with common prefix
> -		 */
>  		if (pmu_is_uncore(name) &&
> -		    !strncmp(pname, name, strlen(pname)))
> +		    pmu_uncore_alias_match(pname, name))
>  			goto new_alias;
>  
>  		if (strcmp(pname, name))
> -- 
> 2.17.1

-- 

- Arnaldo