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

Ravi Bangoria
2022-04-26T11:43:44Z

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