Re: [PATCH 4/9] perf/x86/intel: Support hardware TopDown metrics

["Liang, Kan" <kan.liang@linux.intel.com>]

On 5/28/2019 9:43 AM, Peter Zijlstra wrote:
> On Tue, May 21, 2019 at 02:40:50PM -0700, kan.liang@linux.intel.com wrote:
>> @@ -3287,6 +3304,13 @@ static int core_pmu_hw_config(struct perf_event *event)
>>   	return intel_pmu_bts_config(event);
>>   }
>>   
>> +#define EVENT_CODE(e)	(e->attr.config & INTEL_ARCH_EVENT_MASK)
>> +#define is_slots_event(e)	(EVENT_CODE(e) == 0x0400)
>> +#define is_perf_metrics_event(e)				\
>> +		(((EVENT_CODE(e) & 0xff) == 0xff) &&		\
>> +		 (EVENT_CODE(e) >= 0x01ff) &&			\
>> +		 (EVENT_CODE(e) <= 0x04ff))
>> +
> 
> That is horrific.. (e & INTEL_ARCH_EVENT_MASK) & 0xff is just daft,
> that should be: (e & ARCH_PERFMON_EVENTSEL_EVENT).
> 
> Also, we already have fake events for event=0, see FIXED2, why are we
> now using event=0xff ?

I think event=0 is for genuine fixed events. Metrics events are fake events.
I didn't find FIXED2 in the code. Could you please share more hints?

Thanks,
Kan