linux-kernel - Re: [PATCH v2 16/27] perf evlist: Warn as events from different hybrid PMUs in a group

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Message-ID: <020eaabf-abdb-4458-a883-2abbd4bbfbbd@linux.intel.com>
Date:   Tue, 16 Mar 2021 13:25:29 +0800
From:   "Jin, Yao" <yao.jin@...ux.intel.com>
To:     Jiri Olsa <jolsa@...hat.com>
Cc:     acme@...nel.org, jolsa@...nel.org, peterz@...radead.org,
        mingo@...hat.com, alexander.shishkin@...ux.intel.com,
        Linux-kernel@...r.kernel.org, ak@...ux.intel.com,
        kan.liang@...el.com, yao.jin@...el.com
Subject: Re: [PATCH v2 16/27] perf evlist: Warn as events from different
 hybrid PMUs in a group

Hi Jiri,

On 3/16/2021 7:03 AM, Jiri Olsa wrote:
> On Thu, Mar 11, 2021 at 03:07:31PM +0800, Jin Yao wrote:
> 
> SNIP
> 
>>   				goto try_again;
>>   			}
>> +
>> +			if (errno == EINVAL && perf_pmu__hybrid_exist())
>> +				evlist__warn_hybrid_group(evlist);
>>   			rc = -errno;
>>   			evsel__open_strerror(pos, &opts->target, errno, msg, sizeof(msg));
>>   			ui__error("%s\n", msg);
>> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
>> index 7a732508b2b4..6f780a039db0 100644
>> --- a/tools/perf/builtin-stat.c
>> +++ b/tools/perf/builtin-stat.c
>> @@ -239,6 +239,9 @@ static void evlist__check_cpu_maps(struct evlist *evlist)
>>   	struct evsel *evsel, *pos, *leader;
>>   	char buf[1024];
>>   
>> +	if (evlist__hybrid_exist(evlist))
>> +		return;
> 
> this should be in separate patch and explained
> 

Now I have another idea. If a group consists of atom events and core events, we still follow current 
disabling group solution?

I mean removing following code:

if (evlist__hybrid_exist(evlist))
	return;

evlist__check_cpu_maps then continues running and disabling the group. But also report with a 
warning that says "WARNING: Group has events from different hybrid PMUs".

Do you like this way?

>> +
>>   	evlist__for_each_entry(evlist, evsel) {
>>   		leader = evsel->leader;
>>   
>> @@ -726,6 +729,10 @@ enum counter_recovery {
>>   static enum counter_recovery stat_handle_error(struct evsel *counter)
>>   {
>>   	char msg[BUFSIZ];
>> +
>> +	if (perf_pmu__hybrid_exist() && errno == EINVAL)
>> +		evlist__warn_hybrid_group(evsel_list);
>> +
>>   	/*
>>   	 * PPC returns ENXIO for HW counters until 2.6.37
>>   	 * (behavior changed with commit b0a873e).
>> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
>> index f139151b9433..5ec891418cdd 100644
>> --- a/tools/perf/util/evlist.c
>> +++ b/tools/perf/util/evlist.c
>> @@ -2224,3 +2224,47 @@ void evlist__invalidate_all_cpus(struct evlist *evlist)
>>   	perf_cpu_map__put(evlist->core.all_cpus);
>>   	evlist->core.all_cpus = perf_cpu_map__empty_new(1);
>>   }
>> +
>> +static bool group_hybrid_conflict(struct evsel *leader)
>> +{
>> +	struct evsel *pos, *prev = NULL;
>> +
>> +	for_each_group_evsel(pos, leader) {
>> +		if (!pos->pmu_name || !perf_pmu__is_hybrid(pos->pmu_name))
>> +			continue;
>> +
>> +		if (prev && strcmp(prev->pmu_name, pos->pmu_name))
>> +			return true;
>> +
>> +		prev = pos;
>> +	}
>> +
>> +	return false;
>> +}
>> +
>> +void evlist__warn_hybrid_group(struct evlist *evlist)
>> +{
>> +	struct evsel *evsel;
>> +
>> +	evlist__for_each_entry(evlist, evsel) {
>> +		if (evsel__is_group_leader(evsel) &&
>> +		    evsel->core.nr_members > 1 &&
> 
> hm, could we just iterate all the members and make sure the first found
> hybrid event's pmu matches the pmu of the rest hybrid events in the list?
> 

'{cpu_core/event1/,cpu_core/event2/}','{cpu_atom/event3/,cpu_atom/event4/}'

Two or more groups need to be supported. We get the first hybrid event's pmu (cpu_core in this 
example) but it doesn't match the cpu_atom/event3/ and cpu_atom/event4/. But actually this case 
should be supported, right?

>> +		    group_hybrid_conflict(evsel)) {
>> +			WARN_ONCE(1, "WARNING: Group has events from "
>> +				     "different hybrid PMUs\n");
>> +			return;
>> +		}
>> +	}
>> +}
>> +
>> +bool evlist__hybrid_exist(struct evlist *evlist)
> 
> evlist__has_hybrid seems better
> 

Yes, agree.

Thanks
Jin Yao

> 
> jirka
>