linux-kernel - Re: [PATCH 2/5] perf pmu: Support more complex PMU event aliasing

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Date:   Tue, 11 Jun 2019 17:22:33 +0100
From:   John Garry <john.garry@...wei.com>
To:     Jiri Olsa <jolsa@...hat.com>
CC:     <peterz@...radead.org>, <mingo@...hat.com>, <acme@...nel.org>,
        <alexander.shishkin@...ux.intel.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 2/5] perf pmu: Support more complex PMU event aliasing

On 11/06/2019 17:10, Jiri Olsa wrote:
> On Mon, Jun 10, 2019 at 05:59:29PM +0800, John Garry wrote:
>> 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 the 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 | 45 ++++++++++++++++++++++++++++++++++++++-----
>>  1 file changed, 40 insertions(+), 5 deletions(-)
>>
>> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
>> index 036047f56efa..f00cae750086 100644
>> --- a/tools/perf/util/pmu.c
>> +++ b/tools/perf/util/pmu.c
>> @@ -700,6 +700,44 @@ 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)
>> +{
>> +	/*
>> +	 * uncore alias may be from different PMU
>> +	 * with common prefix
>> +	 */
>> +	if (!strncmp(pmu_name, name, strlen(pmu_name)))
>> +		return true;
>> +
>> +	/* match strings with delimiter, ',' */
>> +	while (1) {
>> +		const char *delimiter;
>> +		char token[256] = {};
>> +		const char *found_token;
>> +		int token_len;
>> +
>> +		delimiter = strchr(pmu_name, ',');
>> +		if (delimiter) {
>> +			token_len = delimiter - pmu_name;
>> +		} else {
>> +			token_len = strlen(pmu_name);
>> +		}
>> +
>> +		memcpy(token, pmu_name, token_len);
>> +
>> +		found_token = strstr(name, token);
>> +		if (!found_token)
>> +			return false;
>> +
>> +		/* No more delimiters, so we must be a match */
>> +		if (!delimiter)
>> +			return true;
>> +
>> +		pmu_name += token_len + 1;
>> +		name = found_token + token_len;
>> +	}
>
> hum, would this be easier with strtok_r?

Yes, I think so.

Cheers,

>
> jirka
>
> .
>