Re: [PATCH V3 1/9] perf report: Fix --total-cycles --stdio output error

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

On 2024-08-13 2:44 p.m., Arnaldo Carvalho de Melo wrote:
> On Tue, Aug 13, 2024 at 09:02:00AM -0700, kan.liang@linux.intel.com wrote:
>> From: Kan Liang <kan.liang@linux.intel.com>
>>
>> The --total-cycles may output wrong information with the --stdio.
> 
> Hey, I tried --total-cycles with --group but that didn't work, do you
> think that would make sense?

The current implementation doesn't handle the symbol_conf.event_group
for the tui mode.
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/perf/builtin-report.c#n543

I will send a separate patch to fix it and make it consistent.

Thanks,
Kan

> 
> Anyway, all applied, now testing and reviewing the changes,
> 
> thanks!
> 
> - Arnaldo
>  
>> For example,
>>   perf record -e "{cycles,instructions}",cache-misses -b sleep 1
>>   perf report --total-cycles --stdio
>>
>> The total cycles output of {cycles,instructions} and cache-misses are
>> almost the same.
>>
>>  # Samples: 938  of events 'anon group { cycles, instructions }'
>>  # Event count (approx.): 938
>>  #
>>  # Sampled Cycles%  Sampled Cycles  Avg Cycles%  Avg Cycles
>>  # ...............  ..............  ...........  ..........
>>   ..................................................>
>>  #
>>            11.19%            2.6K        0.10%          21
>>                           [perf_iterate_ctx+48 -> >
>>             5.79%            1.4K        0.45%          97
>>             [__intel_pmu_enable_all.constprop.0+80 -> __intel_>
>>             5.11%            1.2K        0.33%          71
>>                              [native_write_msr+0 ->>
>>
>>  # Samples: 293  of event 'cache-misses'
>>  # Event count (approx.): 293
>>  #
>>  # Sampled Cycles%  Sampled Cycles  Avg Cycles%  Avg Cycles
>>                                                   [>
>>  # ...............  ..............  ...........  ..........
>>    ..................................................>
>>  #
>>            11.19%            2.6K        0.13%          21
>>                           [perf_iterate_ctx+48 -> >
>>             5.79%            1.4K        0.59%          97
>> [__intel_pmu_enable_all.constprop.0+80 -> __intel_>
>>             5.11%            1.2K        0.43%          71
>>                              [native_write_msr+0 ->>
>>
>> With the symbol_conf.event_group, the perf report should only report the
>> block information of the leader event in a group.
>> However, the current implementation retrieves the next event's block
>> information, rather than the next group leader's block information.
>>
>> Make sure the index is updated even if the event is skipped.
>>
>> With the patch,
>>
>>  # Samples: 293  of event 'cache-misses'
>>  # Event count (approx.): 293
>>  #
>>  # Sampled Cycles%  Sampled Cycles  Avg Cycles%  Avg Cycles
>>                                                   [>
>>  # ...............  ..............  ...........  ..........
>>    ..................................................>
>>  #
>>            37.98%            9.0K        4.05%         299
>>    [perf_event_addr_filters_exec+0 -> perf_event_a>
>>            11.19%            2.6K        0.28%          21
>>                           [perf_iterate_ctx+48 -> >
>>             5.79%            1.4K        1.32%          97
>> [__intel_pmu_enable_all.constprop.0+80 -> __intel_>
>>
>> Fixes: 6f7164fa231a ("perf report: Sort by sampled cycles percent per block for stdio")
>> Acked-by: Namhyung Kim <namhyung@kernel.org>
>> Reviewed-by: Andi Kleen <ak@linux.intel.com>
>> Signed-off-by: Kan Liang <kan.liang@linux.intel.com>
>> ---
>>  tools/perf/builtin-report.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
>> index dfb47fa85e5c..04b9a5c1bc7e 100644
>> --- a/tools/perf/builtin-report.c
>> +++ b/tools/perf/builtin-report.c
>> @@ -565,6 +565,7 @@ static int evlist__tty_browse_hists(struct evlist *evlist, struct report *rep, c
>>  		struct hists *hists = evsel__hists(pos);
>>  		const char *evname = evsel__name(pos);
>>  
>> +		i++;
>>  		if (symbol_conf.event_group && !evsel__is_group_leader(pos))
>>  			continue;
>>  
>> @@ -574,7 +575,7 @@ static int evlist__tty_browse_hists(struct evlist *evlist, struct report *rep, c
>>  		hists__fprintf_nr_sample_events(hists, rep, evname, stdout);
>>  
>>  		if (rep->total_cycles_mode) {
>> -			report__browse_block_hists(&rep->block_reports[i++].hist,
>> +			report__browse_block_hists(&rep->block_reports[i - 1].hist,
>>  						   rep->min_percent, pos, NULL);
>>  			continue;
>>  		}
>> -- 
>> 2.38.1
>