Re: [PATCH 3/6] perf: add reference time event

[David Ahern <dsahern@gmail.com>]

On 06/17/2011 07:32 AM, Frederic Weisbecker wrote:
> On Tue, Jun 07, 2011 at 05:55:46PM -0600, David Ahern wrote:
>> For initial perf_clock to time-of-day correlation.
>>
>> Signed-off-by: David Ahern <dsahern@gmail.com>
>> ---
>>  tools/perf/util/event.c   |    1 +
>>  tools/perf/util/event.h   |    8 ++++++++
>>  tools/perf/util/session.c |    4 ++++
>>  tools/perf/util/session.h |    3 ++-
>>  4 files changed, 15 insertions(+), 1 deletions(-)
>>
>> diff --git a/tools/perf/util/event.c b/tools/perf/util/event.c
>> index 3c1b8a6..1a89a04 100644
>> --- a/tools/perf/util/event.c
>> +++ b/tools/perf/util/event.c
>> @@ -24,6 +24,7 @@ static const char *perf_event__names[] = {
>>  	[PERF_RECORD_HEADER_TRACING_DATA]	= "TRACING_DATA",
>>  	[PERF_RECORD_HEADER_BUILD_ID]		= "BUILD_ID",
>>  	[PERF_RECORD_FINISHED_ROUND]		= "FINISHED_ROUND",
>> +	[PERF_RECORD_REFTIME]			= "REF_TIME",
>>  };
>>  
>>  const char *perf_event__name(unsigned int id)
>> diff --git a/tools/perf/util/event.h b/tools/perf/util/event.h
>> index 1d7f664..f481f90 100644
>> --- a/tools/perf/util/event.h
>> +++ b/tools/perf/util/event.h
>> @@ -98,6 +98,7 @@ enum perf_user_event_type { /* above any possible kernel type */
>>  	PERF_RECORD_HEADER_TRACING_DATA		= 66,
>>  	PERF_RECORD_HEADER_BUILD_ID		= 67,
>>  	PERF_RECORD_FINISHED_ROUND		= 68,
>> +	PERF_RECORD_REFTIME			= 69,
> 
> We would like to avoid adding more custom events like these. They were very convenient
> but they steal the kernel event type space. They are deemed for removal in the long term.
> 
> Another idea to achieve what you want would be to create a new perf event header feature,
> like HEADER_TRACE_INFO or HEADER_BUILD_ID are. Then use that to create a space in the perf
> file to save that couple of clocks initial values.

you mean like this:
https://lkml.org/lkml/2010/12/7/813

David