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Subject: Re: [PATCH] perf tools: Enable on a list of CPUs for hybrid
To:     Arnaldo Carvalho de Melo <acme@kernel.org>
Cc:     jolsa@kernel.org, peterz@infradead.org, mingo@redhat.com,
        alexander.shishkin@linux.intel.com, Linux-kernel@vger.kernel.org,
        ak@linux.intel.com, kan.liang@intel.com, yao.jin@intel.com
References: <20210617070026.14475-1-yao.jin@linux.intel.com>
 <YMtcVkEyb8h/dzCb@kernel.org>
From:   "Jin, Yao" <yao.jin@linux.intel.com>
Message-ID: <d6b39508-04c8-85f1-c327-64d49685433a@linux.intel.com>
Date:   Fri, 18 Jun 2021 10:38:07 +0800
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Hi Arnaldo,

On 6/17/2021 10:29 PM, Arnaldo Carvalho de Melo wrote:
> Em Thu, Jun 17, 2021 at 03:00:26PM +0800, Jin Yao escreveu:
>> The perf-record and perf-stat have supported the option '-C/--cpus'
>> to count or collect only on the list of CPUs provided. This option
>> needs to be supported for hybrid as well.
>>
>> For hybrid support, it needs to check that the CPUs are available on
>> hybrid PMU. On AlderLake, for example, 'cpu_core' has CPU0-CPU15,
>> and 'cpu_atom' has CPU16-CPU23.
>>
>> Before:
>>
>>    # perf stat -e cpu_core/cycles/ -C16 true
>>
>>     Performance counter stats for 'CPU(s) 16':
>>
>>       <not supported>      cpu_core/cycles/
>>
>> The perf-stat silently returned "<not supported>" without any helpful
>> information. It should error out that CPU16 was not available on
>> 'cpu_core'.
>>
>> After:
>>
>>    # perf stat -e cpu_core/cycles/ -C16 true
>>    'cpu_core' doesn't have cpu 16
>>    failed to use cpu list 16
> 
> The above is sensible, as the user specified a specific CPU type
> (cpu_core) and asked for a CPU list that is of another type (cpu_atom).
> Perhaps the message can be improved a bit by checking if the CPU list
> specified is valid for the other cpu type (cpu_atom) and print:
> 
>     # perf stat -e cpu_core/cycles/ -C16 true
>     CPU 16 isn't a 'cpu_core', please use 'cpu_atom/cycles/' or use a CPU list in the 'cpu_core' range (0-15).
>     failed to use cpu list 16
>   

Can we just print the message such as:

"CPU 16 isn't a 'cpu_core', please use a CPU list in the 'cpu_core' range (0-15)".

The user specified the 'cpu_core', so he might only want to enable the event on 'cpu_core'. Maybe we 
directly return the cpulist in 'cpu_core' range is more straightfoward.

>> It also supports to count only on a given CPU.
>   
>>    # perf stat -e cpu_core/cycles/ -C15 -vv true
> 
> Humm, what if I want to count events on some cpu_core CPUs plus on some
> cpu_atom ones?
> 
> I.e. if I do:
> 
> 	perf stat -e cycles -C16
> 

If only with this patch, it would be failed.

# perf stat -e cycles -C 2 -- sleep 1
'cpu_atom' doesn't have cpu 2
failed to use cpu list 2

CPU2 is 'cpu_core', so errors out.

> probably it should map to cpu_atom/cycles/, right? And if I do:
>

Yes, if we can map to cpu_atom/cycles/, that's better.

> 	perf stat -e cycles -C15,16
> 
> This should map to cpu_core/cycles/ on CPU 15 and to cpu_atom/cycles/ on
> CPU 16?
> 

Ditto, if we can map, that's better.

> Or perhaps we should make the CPU list a evsel term? I.e.:
> 
> 	perf stat -e cpu_core/cycles,cpus=15/,cpu_atom/cycles,cpus=16/
>

Introducing a new term 'cpus' is a more flexible solution. I like it! :)

> Or perhaps both?
> 

Let me improve this patch to v2 for soltuion #1 and a follow up patch for solution #2. Is that OK?

Thanks
Jin Yao

> - Arnaldo
> 
>   
>>    ------------------------------------------------------------
>>    perf_event_attr:
>>      size                             128
>>      config                           0x400000000
>>      sample_type                      IDENTIFIER
>>      read_format                      TOTAL_TIME_ENABLED|TOTAL_TIME_RUNNING
>>      disabled                         1
>>      inherit                          1
>>      exclude_guest                    1
>>    ------------------------------------------------------------
>>    sys_perf_event_open: pid -1  cpu 15  group_fd -1  flags 0x8 = 3
>>    cycles: 0: 103287 569776 569776
>>    cycles: 103287 569776 569776
>>
>>     Performance counter stats for 'CPU(s) 15':
>>
>>               103,287      cpu_core/cycles/
>>
>>           0.000566813 seconds time elapsed
>>
>> Collect the counts of 'cycles' on CPU15 (CPU15 is in 'cpu_core').
>>
>> Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
>> ---
>>   tools/perf/builtin-record.c     |  6 +++++
>>   tools/perf/builtin-stat.c       |  5 ++++
>>   tools/perf/util/evlist-hybrid.c | 43 +++++++++++++++++++++++++++++++++
>>   tools/perf/util/evlist-hybrid.h |  1 +
>>   tools/perf/util/evlist.c        |  1 +
>>   tools/perf/util/pmu.c           | 23 ++++++++++++++++++
>>   tools/perf/util/pmu.h           |  3 +++
>>   7 files changed, 82 insertions(+)
>>
>> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
>> index bc3dd379eb67..bd39d4260549 100644
>> --- a/tools/perf/builtin-record.c
>> +++ b/tools/perf/builtin-record.c
>> @@ -2877,6 +2877,12 @@ int cmd_record(int argc, const char **argv)
>>   	/* Enable ignoring missing threads when -u/-p option is defined. */
>>   	rec->opts.ignore_missing_thread = rec->opts.target.uid != UINT_MAX || rec->opts.target.pid;
>>   
>> +	if (evlist__use_cpu_list(rec->evlist, rec->opts.target.cpu_list)) {
>> +		pr_err("failed to use cpu list %s\n",
>> +		       rec->opts.target.cpu_list);
>> +		goto out;
>> +	}
>> +
>>   	err = -ENOMEM;
>>   	if (evlist__create_maps(rec->evlist, &rec->opts.target) < 0)
>>   		usage_with_options(record_usage, record_options);
>> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
>> index f9f74a514315..9c27c90d069f 100644
>> --- a/tools/perf/builtin-stat.c
>> +++ b/tools/perf/builtin-stat.c
>> @@ -2427,6 +2427,11 @@ int cmd_stat(int argc, const char **argv)
>>   	if ((stat_config.aggr_mode == AGGR_THREAD) && (target.system_wide))
>>   		target.per_thread = true;
>>   
>> +	if (evlist__use_cpu_list(evsel_list, target.cpu_list)) {
>> +		pr_err("failed to use cpu list %s\n", target.cpu_list);
>> +		goto out;
>> +	}
>> +
>>   	if (evlist__create_maps(evsel_list, &target) < 0) {
>>   		if (target__has_task(&target)) {
>>   			pr_err("Problems finding threads of monitor\n");
>> diff --git a/tools/perf/util/evlist-hybrid.c b/tools/perf/util/evlist-hybrid.c
>> index db3f5fbdebe1..e8fdd98aed3f 100644
>> --- a/tools/perf/util/evlist-hybrid.c
>> +++ b/tools/perf/util/evlist-hybrid.c
>> @@ -86,3 +86,46 @@ bool evlist__has_hybrid(struct evlist *evlist)
>>   
>>   	return false;
>>   }
>> +
>> +int evlist__use_cpu_list(struct evlist *evlist, const char *cpu_list)
>> +{
>> +	struct perf_cpu_map *cpus;
>> +	struct evsel *evsel;
>> +	struct perf_pmu *pmu;
>> +	int ret;
>> +
>> +	if (!perf_pmu__has_hybrid() || !cpu_list)
>> +		return 0;
>> +
>> +	cpus = perf_cpu_map__new(cpu_list);
>> +	if (!cpus)
>> +		return -1;
>> +
>> +	evlist__for_each_entry(evlist, evsel) {
>> +		bool exact_match;
>> +
>> +		pmu = perf_pmu__find_hybrid_pmu(evsel->pmu_name);
>> +		if (!pmu)
>> +			continue;
>> +
>> +		if (!perf_pmu__cpus_matched(pmu, cpus, &exact_match)) {
>> +			ret = -1;
>> +			goto out;
>> +		}
>> +
>> +		if (!exact_match) {
>> +			/*
>> +			 * Use the cpus in cpu_list.
>> +			 */
>> +			perf_cpu_map__put(evsel->core.cpus);
>> +			perf_cpu_map__put(evsel->core.own_cpus);
>> +			evsel->core.cpus = perf_cpu_map__get(cpus);
>> +			evsel->core.own_cpus = perf_cpu_map__get(cpus);
>> +		}
>> +	}
>> +
>> +	ret = 0;
>> +out:
>> +	perf_cpu_map__put(cpus);
>> +	return ret;
>> +}
>> diff --git a/tools/perf/util/evlist-hybrid.h b/tools/perf/util/evlist-hybrid.h
>> index 19f74b4c340a..f33a4e8443a1 100644
>> --- a/tools/perf/util/evlist-hybrid.h
>> +++ b/tools/perf/util/evlist-hybrid.h
>> @@ -10,5 +10,6 @@
>>   int evlist__add_default_hybrid(struct evlist *evlist, bool precise);
>>   void evlist__warn_hybrid_group(struct evlist *evlist);
>>   bool evlist__has_hybrid(struct evlist *evlist);
>> +int evlist__use_cpu_list(struct evlist *evlist, const char *cpu_list);
>>   
>>   #endif /* __PERF_EVLIST_HYBRID_H */
>> diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
>> index 6ba9664089bd..e8a0f95f7f47 100644
>> --- a/tools/perf/util/evlist.c
>> +++ b/tools/perf/util/evlist.c
>> @@ -27,6 +27,7 @@
>>   #include "util/perf_api_probe.h"
>>   #include "util/evsel_fprintf.h"
>>   #include "util/evlist-hybrid.h"
>> +#include "util/pmu.h"
>>   #include <signal.h>
>>   #include <unistd.h>
>>   #include <sched.h>
>> diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
>> index 88c8ecdc60b0..0e3a19a6736d 100644
>> --- a/tools/perf/util/pmu.c
>> +++ b/tools/perf/util/pmu.c
>> @@ -1872,3 +1872,26 @@ bool perf_pmu__has_hybrid(void)
>>   
>>   	return !list_empty(&perf_pmu__hybrid_pmus);
>>   }
>> +
>> +bool perf_pmu__cpus_matched(struct perf_pmu *pmu, struct perf_cpu_map *cpus,
>> +			    bool *exact_match)
>> +{
>> +	struct perf_cpu_map *pmu_cpus = pmu->cpus;
>> +	int cpu;
>> +
>> +	*exact_match = false;
>> +
>> +	for (int i = 0; i < cpus->nr; i++) {
>> +		cpu = perf_cpu_map__idx(pmu_cpus, cpus->map[i]);
>> +		if (cpu == -1) {
>> +			pr_err("'%s' doesn't have cpu %d\n",
>> +			       pmu->name, cpus->map[i]);
>> +			return false;
>> +		}
>> +	}
>> +
>> +	if (cpus->nr == pmu_cpus->nr)
>> +		*exact_match = true;
>> +
>> +	return true;
>> +}
>> diff --git a/tools/perf/util/pmu.h b/tools/perf/util/pmu.h
>> index a790ef758171..1cca48e02b5d 100644
>> --- a/tools/perf/util/pmu.h
>> +++ b/tools/perf/util/pmu.h
>> @@ -11,6 +11,7 @@
>>   #include "pmu-events/pmu-events.h"
>>   
>>   struct evsel_config_term;
>> +struct perf_cpu_map;
>>   
>>   enum {
>>   	PERF_PMU_FORMAT_VALUE_CONFIG,
>> @@ -133,5 +134,7 @@ void perf_pmu__warn_invalid_config(struct perf_pmu *pmu, __u64 config,
>>   				   char *name);
>>   
>>   bool perf_pmu__has_hybrid(void);
>> +bool perf_pmu__cpus_matched(struct perf_pmu *pmu, struct perf_cpu_map *cpus,
>> +			    bool *exact_match);
>>   
>>   #endif /* __PMU_H */
>> -- 
>> 2.17.1
>>
>