linux-kernel - Re: [PATCH v3 3/3] perf tools: Enable on a list of CPUs for hybrid

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Message-ID: <YPaUc3iodIASdYRY@krava>
Date:   Tue, 20 Jul 2021 11:16:35 +0200
From:   Jiri Olsa <jolsa@...hat.com>
To:     "Jin, Yao" <yao.jin@...ux.intel.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 v3 3/3] perf tools: Enable on a list of CPUs for hybrid

On Tue, Jul 20, 2021 at 03:07:02PM +0800, Jin, Yao wrote:

SNIP

> 
> OK, evlist__fix_cpus() is better, use this name in v4.
> 
> > > +{
> > > +	struct perf_cpu_map *cpus;
> > > +	struct evsel *evsel, *tmp;
> > > +	struct perf_pmu *pmu;
> > > +	int ret, unmatched_count = 0, events_nr = 0;
> > > +
> > > +	if (!perf_pmu__has_hybrid() || !cpu_list)
> > > +		return 0;
> > > +
> > > +	cpus = perf_cpu_map__new(cpu_list);
> > > +	if (!cpus)
> > > +		return -1;
> > > +
> > > +	evlist__for_each_entry_safe(evlist, tmp, evsel) {
> > > +		struct perf_cpu_map *matched_cpus, *unmatched_cpus;
> > > +		char buf1[128], buf2[128];
> > > +
> > > +		pmu = perf_pmu__find_hybrid_pmu(evsel->pmu_name);
> > > +		if (!pmu)
> > > +			continue;
> > > +
> > > +		ret = perf_pmu__cpus_match(pmu, cpus, &matched_cpus,
> > > +					   &unmatched_cpus);
> > > +		if (ret)
> > > +			goto out;
> > > +
> > > +		events_nr++;
> > > +
> > > +		if (matched_cpus->nr > 0 && (unmatched_cpus->nr > 0 ||
> > > +		    matched_cpus->nr < cpus->nr ||
> > > +		    matched_cpus->nr < pmu->cpus->nr)) {
> > > +			perf_cpu_map__put(evsel->core.cpus);
> > > +			perf_cpu_map__put(evsel->core.own_cpus);
> > > +			evsel->core.cpus = perf_cpu_map__get(matched_cpus);
> > > +			evsel->core.own_cpus = perf_cpu_map__get(matched_cpus);
> > 
> > I'm bit confused in here.. AFAIUI there's 2 evsel objects create
> > for hybrid 'cycles' ... should they have already proper cpus set?
> > 
> 
> For 'cycles', yes two evsels are created automatically. One is for atom CPU
> (e.g. 8-11), the other is for core CPU (e.g. 0-7). In this example, these 2
> evsels have already the cpus set.

hum, so those evsels are created with pmu's cpus, right?

> 
> While the 'cpus' here is just the user specified cpu list.
> cpus = perf_cpu_map__new(cpu_list);

then I think they will be changed by evlist__create_maps
with whatever user wants?

could we just change __perf_evlist__propagate_maps to follow
pmu's cpus?

jirka

> 
> We need to check that the cpu in 'cpus' is available on hybrid pmu or not
> and adjust the evsel->core.cpus according the matching results.
> 
> > > +
> > > +			if (unmatched_cpus->nr > 0) {
> > > +				cpu_map__snprint(matched_cpus, buf1, sizeof(buf1));
> > > +				pr_warning("WARNING: use %s in '%s' for '%s', skip other cpus in list.\n",
> > > +					   buf1, pmu->name, evsel->name);
> > > +			}
> > > +		}
> > > +
> > > +		if (matched_cpus->nr == 0) {
> > > +			evlist__remove(evlist, evsel);
> > > +			evsel__delete(evsel);
> > > +
> > > +			cpu_map__snprint(cpus, buf1, sizeof(buf1));
> > > +			cpu_map__snprint(pmu->cpus, buf2, sizeof(buf2));
> > > +			pr_warning("WARNING: %s isn't a '%s', please use a CPU list in the '%s' range (%s)\n",
> > > +				   buf1, pmu->name, pmu->name, buf2);
> > > +			unmatched_count++;
> > > +		}
> > 
> > hum, should we rather fail in here?
> > 
> 
> perf stat -e cpu_core/cycles/,cpu_atom/instructions/ -C11
> 
> CPU11 is atom CPU so the evsel 'cpu_core/cycles/' is failed but cpu_atom/instructions/ is OK.
> 
> Don't we report the partially successful event?
> 
> Thanks
> Jin Yao
> 
> > jirka
> > 
>