Re: [PATCH 3/6] perf/tool/amd/ibs: Warn about sampling period skew

[Ravi Bangoria <ravi.bangoria@amd.com>]

On 26-Apr-22 3:39 PM, Robert Richter wrote:
> On 25.04.22 10:13:20, Ravi Bangoria wrote:
> 
>> @@ -29,3 +31,32 @@ void arch_evsel__fixup_new_cycles(struct perf_event_attr *attr)
>>  
>>  	free(env.cpuid);
>>  }
>> +
>> +void arch_evsel__warn_ambiguity(struct evsel *evsel, struct perf_event_attr *attr)
> 
> Have an 'ibs_' string in the name?

No, this is not ibs specific. Any arch can define it's own version.

> 
>> +{
>> +	struct perf_env *env = evsel__env(evsel);
>> +	struct perf_pmu *evsel_pmu = evsel__find_pmu(evsel);
>> +	struct perf_pmu *ibs_fetch_pmu = perf_pmu__find("ibs_fetch");
>> +	struct perf_pmu *ibs_op_pmu = perf_pmu__find("ibs_op");
>> +	static int warned_once;
>> +
>> +	if (warned_once || !perf_env__cpuid(env) || !env->cpuid ||
>> +	    !strstarts(env->cpuid, "AuthenticAMD") || !evsel_pmu)
>> +		return;
>> +
>> +	if (ibs_fetch_pmu && ibs_fetch_pmu->type == evsel_pmu->type) {
>> +		if (attr->config & (1ULL << 59)) {
>> +			pr_warning(
>> +"WARNING: Hw internally resets sampling period when L3 Miss Filtering is enabled\n"
>> +"and tagged operation does not cause L3 Miss. This causes sampling period skew.\n");
>> +			warned_once = 1;
>> +		}
>> +	} else if (ibs_op_pmu && ibs_op_pmu->type == evsel_pmu->type) {
>> +		if (attr->config & (1ULL << 16)) {
>> +			pr_warning(
>> +"WARNING: Hw internally resets sampling period when L3 Miss Filtering is enabled\n"
>> +"and tagged operation does not cause L3 Miss. This causes sampling period skew.\n");
> 
> Avoid duplicate code. You could move it to the end of the function and
> early return if the config bit is not set.

Sure.

Thanks,
Ravi