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SubjectRe: [PATCH v6 2/6] perf record: Get the first sample time and last sample time
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On 11/22/2017 12:40 AM, Arnaldo Carvalho de Melo wrote:
> Em Mon, Nov 06, 2017 at 08:21:07PM +0800, Jin Yao escreveu:
>> In perf record, it's walked on all samples yet. So it's very easy to get
>
> "In the default 'perf record' configuration, all samples are processed,
> to create the HEADER_BUILD_ID table. So..."
>
>> 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.
>
> Later, at post processing time, ...
>

Thanks Arnaldo! The update on patch description is good.

>>
>> Change log:
>> -----------
>> v6: Currently '--buildid-all' is not enabled at default. So the walking
>
> --no-buildid-all, right?
>

No, it is '--buildid-all'. There is no '--no-buildid-all' available now.

See in __record_options[] (builtin-record.c),

OPT_BOOLEAN(0, "buildid-all", &record.buildid_all,
"Record build-id of all DSOs regardless of hits"),

So by default, buildid-all is set with false.

Thanks
Jin Yao

>> on all samples is the default operation. There is no big overhead
>> to calculate the timestamp boundary in process_sample_event handler
>> once we already go through all samples. So the timestamp boundary
>> calculation is enabled by default when '--buildid-all' is not enabled.
>>
>> While if '--buildid-all' is enabled, we creates a new option
>> "--timestamp-boundary" for user to decide if it enables the
>> timestamp boundary calculation.
>>
>> 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@linux.intel.com>
>> ---
>> tools/perf/Documentation/perf-record.txt | 3 +++
>> tools/perf/builtin-record.c | 18 +++++++++++++++---
>> 2 files changed, 18 insertions(+), 3 deletions(-)
>>
>> diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
>> index 5a626ef..3eea6de 100644
>> --- a/tools/perf/Documentation/perf-record.txt
>> +++ b/tools/perf/Documentation/perf-record.txt
>> @@ -430,6 +430,9 @@ Configure all used events to run in user space.
>> --timestamp-filename
>> Append timestamp to output file name.
>>
>> +--timestamp-boundary::
>> +Record timestamp boundary (time of first/last samples).
>> +
>> --switch-output[=mode]::
>> Generate multiple perf.data files, timestamp prefixed, switching to a new one
>> based on 'mode' value:
>> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
>> index f4d9fc5..082a0cb 100644
>> --- a/tools/perf/builtin-record.c
>> +++ b/tools/perf/builtin-record.c
>> @@ -78,6 +78,7 @@ struct record {
>> bool no_buildid_cache_set;
>> bool buildid_all;
>> bool timestamp_filename;
>> + bool timestamp_boundary;
>> struct switch_output switch_output;
>> unsigned long long samples;
>> };
>> @@ -391,8 +392,15 @@ 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 (rec->buildid_all)
>> + return 0;
>> +
>> + rec->samples++;
>> return build_id__mark_dso_hit(tool, event, sample, evsel, machine);
>> }
>>
>> @@ -417,9 +425,11 @@ static int process_buildids(struct record *rec)
>>
>> /*
>> * If --buildid-all is given, it marks all DSO regardless of hits,
>> - * so no need to process samples.
>> + * so no need to process samples. But if timestamp_boundary is enabled,
>> + * it still needs to walk on all samples to get the timestamps of
>> + * first/last samples.
>> */
>> - if (rec->buildid_all)
>> + if (rec->buildid_all && !rec->timestamp_boundary)
>> rec->tool.sample = NULL;
>>
>> return perf_session__process_events(session);
>> @@ -1579,6 +1589,8 @@ static struct option __record_options[] = {
>> "Record build-id of all DSOs regardless of hits"),
>> OPT_BOOLEAN(0, "timestamp-filename", &record.timestamp_filename,
>> "append timestamp to output filename"),
>> + OPT_BOOLEAN(0, "timestamp-boundary", &record.timestamp_boundary,
>> + "Record timestamp boundary (time of first/last samples)"),
>> OPT_STRING_OPTARG_SET(0, "switch-output", &record.switch_output.str,
>> &record.switch_output.set, "signal,size,time",
>> "Switch output when receive SIGUSR2 or cross size,time threshold",
>> --
>> 2.7.4

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