linux-kernel - Re: [PATCH v5 2/6] perf record: Get the first sample time and last sample time

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Date:   Tue, 24 Oct 2017 01:38:26 +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 v5 2/6] perf record: Get the first sample time and last
 sample time



On 10/23/2017 11:04 PM, Jiri Olsa wrote:
> On Sat, Oct 21, 2017 at 07:27:50AM +0800, Jin Yao wrote:
>> In perf record, it's walked on all samples yet. So it's very easy to get
>> the first/last samples and save the time to perf file header via the
>> function write_sample_time().
>>
>> In later, perf report/script will fetch the time from perf file header.
>>
>> Change log:
>> -----------
>> v5: There is an issue that the sample walking can only work when
>>      '--buildid-all' is not enabled. So we need to let the walking
>>      be able to work even if '--buildid-all' is enabled and let the
>>      processing skips the dso hit marking for this case.
>>
>>      At first, I want to provide a new option "--record-time-boundaries".
>>      While after consideration, I think a new option is not very
>>      necessary.
>>
>> v3: Remove the definitions of first_sample_time and last_sample_time
>>      from struct record and directly save them in perf_evlist.
>>
>> Signed-off-by: Jin Yao <yao.jin@...ux.intel.com>
>> ---
>>   tools/perf/builtin-record.c | 20 ++++++++++++--------
>>   1 file changed, 12 insertions(+), 8 deletions(-)
>>
>> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
>> index a6cbf16..bd711e8 100644
>> --- a/tools/perf/builtin-record.c
>> +++ b/tools/perf/builtin-record.c
>> @@ -391,8 +391,19 @@ static int process_sample_event(struct perf_tool *tool,
>>   {
>>   	struct record *rec = container_of(tool, struct record, tool);
>>   
>> -	rec->samples++;
>> +	if (rec->evlist->first_sample_time == 0)
>> +		rec->evlist->first_sample_time = sample->time;
>> +
>> +	rec->evlist->last_sample_time = sample->time;
>> +
>> +	/*
>> +	 * If --buildid-all is given, it marks all DSO regardless of hits,
>> +	 * so no need to process this sample.
>> +	 */
>> +	if (rec->buildid_all)
>> +		return 0;
>>   
>> +	rec->samples++;
>>   	return build_id__mark_dso_hit(tool, event, sample, evsel, machine);
>>   }
>>   
>> @@ -415,13 +426,6 @@ static int process_buildids(struct record *rec)
>>   	 */
>>   	symbol_conf.ignore_vmlinux_buildid = true;
>>   
>> -	/*
>> -	 * If --buildid-all is given, it marks all DSO regardless of hits,
>> -	 * so no need to process samples.
>> -	 */
>> -	if (rec->buildid_all)
>> -		rec->tool.sample = NULL;
> 
> hum, could you still unset the sample if there's no time given?
> and keep the speed in this case..
> 
> jirka
> 

Oh, yes, I should do that. Thanks Jiri!

Hi Arnaldo, do you have any comment for v5?

I will prepare v6 for adding fixes according to all comments.

Thanks
Jin Yao