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Subject: Re: [PATCH v3 4/4] perf stat: Report summary for interval mode
To:     Jiri Olsa <jolsa@redhat.com>
Cc:     acme@kernel.org, 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: <20200507065822.8255-1-yao.jin@linux.intel.com>
 <20200507065822.8255-5-yao.jin@linux.intel.com>
 <20200507151858.GD2804092@krava>
From:   "Jin, Yao" <yao.jin@linux.intel.com>
Message-ID: <70c2dcf8-beab-bc3a-09d1-e9f3cb6e1cc2@linux.intel.com>
Date:   Fri, 8 May 2020 09:11:49 +0800
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Hi Jiri,

On 5/7/2020 11:18 PM, Jiri Olsa wrote:
> On Thu, May 07, 2020 at 02:58:22PM +0800, Jin Yao wrote:
>> Currently perf-stat supports to print counts at regular interval (-I),
>> but it's not very easy for user to get the overall statistics.
>>
>> The patch uses 'evsel->prev_raw_counts' to get counts for summary.
>> Copy the counts to 'evsel->counts' after printing the interval results.
>> Next, we just follow the non-interval processing.
>>
>> Let's see some examples,
>>
>>   root@kbl-ppc:~# perf stat -e cycles -I1000 --interval-count 2
>>   #           time             counts unit events
>>        1.000412064          2,281,114      cycles
>>        2.001383658          2,547,880      cycles
>>
>>    Performance counter stats for 'system wide':
>>
>>            4,828,994      cycles
>>
>>          2.002860349 seconds time elapsed
>>
>>   root@kbl-ppc:~# perf stat -e cycles,instructions -I1000 --interval-count 2
>>   #           time             counts unit events
>>        1.000389902          1,536,093      cycles
>>        1.000389902            420,226      instructions              #    0.27  insn per cycle
>>        2.001433453          2,213,952      cycles
>>        2.001433453            735,465      instructions              #    0.33  insn per cycle
>>
>>    Performance counter stats for 'system wide':
>>
>>            3,750,045      cycles
>>            1,155,691      instructions              #    0.31  insn per cycle
>>
>>          2.003023361 seconds time elapsed
>>
>>   root@kbl-ppc:~# perf stat -M CPI,IPC -I1000 --interval-count 2
>>   #           time             counts unit events
>>        1.000435121            905,303      inst_retired.any          #      2.9 CPI
>>        1.000435121          2,663,333      cycles
>>        1.000435121            914,702      inst_retired.any          #      0.3 IPC
>>        1.000435121          2,676,559      cpu_clk_unhalted.thread
>>        2.001615941          1,951,092      inst_retired.any          #      1.8 CPI
>>        2.001615941          3,551,357      cycles
>>        2.001615941          1,950,837      inst_retired.any          #      0.5 IPC
>>        2.001615941          3,551,044      cpu_clk_unhalted.thread
>>
>>    Performance counter stats for 'system wide':
>>
>>            2,856,395      inst_retired.any          #      2.2 CPI
>>            6,214,690      cycles
>>            2,865,539      inst_retired.any          #      0.5 IPC
>>            6,227,603      cpu_clk_unhalted.thread
>>
>>          2.003403078 seconds time elapsed
>>
>>   v3:
>>   ---
>>   Use evsel->prev_raw_counts for summary counts
>>
>>   v2:
>>   ---
>>   Rebase to perf/core branch
>>
>> Signed-off-by: Jin Yao <yao.jin@linux.intel.com>
>> ---
>>   tools/perf/builtin-stat.c | 16 ++++++++++++++--
>>   tools/perf/util/stat.c    |  2 +-
>>   tools/perf/util/stat.h    |  1 +
>>   3 files changed, 16 insertions(+), 3 deletions(-)
>>
>> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
>> index 97ee941649e6..f67d6a50274e 100644
>> --- a/tools/perf/builtin-stat.c
>> +++ b/tools/perf/builtin-stat.c
>> @@ -334,7 +334,7 @@ static void read_counters(struct timespec *rs)
>>   		evlist__for_each_entry(evsel_list, counter) {
>>   			if (evsel__cpu_iter_skip(counter, cpu))
>>   				continue;
>> -			if (!counter->err) {
>> +			if (!counter->err && !stat_config.summary) {
> 
> you'll go through all the affinity setup and do nothing at the end,
> even if you know at the begining that it's the case.. not good
> 
> we need to call only the perf_stat_process_counter in summary case
> 
> jirka
> 

The interval processing and non-interval processing both need to call 
read_counters.

I need to prevent calling read_counter_cpu in read_counters for non-interval 
otherwise the summary counts will be bigger than the sum of interval counts.

e.g.
interval: read_counter_cpu
interval: read_counter_cpu
interval: read_counter_cpu
interval mode is over,
non-interval: read_counter_cpu /* prevent this time read_counter_cpu */

Since read_counter_cpu is called before perf_stat_process_counter, so I can't do 
this in perf_stat_process_counter.

Yes, it's not good to check stat_config.summary in loops, low efficiency.

Maybe we can move the codes of affinity setup and read_counter_cpu to a new 
function, such as affinity_read_counters and change the read_counters to:

void read_counters()
{
	if (!stat_config.summary)
		affinity_read_counters();

	evlist__for_each_entry(evsel_list, counter) {
		perf_stat_process_counter(&stat_config, counter));
	}
}

Thanks
Jin Yao

>>   				counter->err = read_counter_cpu(counter, rs,
>>   								counter->cpu_iter - 1);
>>   			}
>> @@ -364,6 +364,7 @@ static void thread_stats_reset(struct perf_stat_config *config)
>>   static void process_interval(void)
>>   {
>>   	struct timespec ts, rs;
>> +	struct stats walltime_nsecs_stats_bak;
>>   
>>   	clock_gettime(CLOCK_MONOTONIC, &ts);
>>   	diff_timespec(&rs, &ts, &ref_time);
>> @@ -377,9 +378,11 @@ static void process_interval(void)
>>   			pr_err("failed to write stat round event\n");
>>   	}
>>   
>> +	walltime_nsecs_stats_bak = walltime_nsecs_stats;
>>   	init_stats(&walltime_nsecs_stats);
>>   	update_stats(&walltime_nsecs_stats, stat_config.interval * 1000000);
>>   	print_counters(&rs, 0, NULL);
>> +	walltime_nsecs_stats = walltime_nsecs_stats_bak;
>>   }
>>   
>>   static void enable_counters(void)
>> @@ -735,6 +738,15 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
>>   
>>   	update_stats(&walltime_nsecs_stats, t1 - t0);
>>   
>> +	if (interval) {
>> +		stat_config.interval = 0;
>> +		stat_config.summary = true;
>> +		perf_evlist__copy_prev_raw_counts(evsel_list);
>> +		perf_evlist__reset_prev_raw_counts(evsel_list);
>> +		thread_stats_reset(&stat_config);
>> +		perf_stat__reset_shadow_per_stat(&rt_stat);
>> +	}
>> +
>>   	/*
>>   	 * Closing a group leader splits the group, and as we only disable
>>   	 * group leaders, results in remaining events becoming enabled. To
>> @@ -2158,7 +2170,7 @@ int cmd_stat(int argc, const char **argv)
>>   		}
>>   	}
>>   
>> -	if (!forever && status != -1 && !interval)
>> +	if (!forever && status != -1 && (!interval || stat_config.summary))
>>   		print_counters(NULL, argc, argv);
>>   
>>   	if (STAT_RECORD) {
>> diff --git a/tools/perf/util/stat.c b/tools/perf/util/stat.c
>> index ede113805ecd..47b26c024830 100644
>> --- a/tools/perf/util/stat.c
>> +++ b/tools/perf/util/stat.c
>> @@ -393,7 +393,7 @@ int perf_stat_process_counter(struct perf_stat_config *config,
>>   	 * interval mode, otherwise overall avg running
>>   	 * averages will be shown for each interval.
>>   	 */
>> -	if (config->interval) {
>> +	if (config->interval || config->summary) {
>>   		for (i = 0; i < 3; i++)
>>   			init_stats(&ps->res_stats[i]);
>>   	}
>> diff --git a/tools/perf/util/stat.h b/tools/perf/util/stat.h
>> index 62cf72c71869..c60e9e5d6474 100644
>> --- a/tools/perf/util/stat.h
>> +++ b/tools/perf/util/stat.h
>> @@ -110,6 +110,7 @@ struct perf_stat_config {
>>   	bool			 all_kernel;
>>   	bool			 all_user;
>>   	bool			 percore_show_thread;
>> +	bool			 summary;
>>   	FILE			*output;
>>   	unsigned int		 interval;
>>   	unsigned int		 timeout;
>> -- 
>> 2.17.1
>>
>