Re: [PATCH v2 1/3] perf: add PERF_RECORD_NAMESPACES to include namespaces related info

[Hari Bathini]

Hi Peter,


Sorry for taking so long to respond...


On Thursday 24 November 2016 08:40 PM, Peter Zijlstra wrote:
> On Thu, Nov 24, 2016 at 08:14:29PM +0530, Hari Bathini wrote:
> > @@ -862,6 +875,19 @@ enum perf_event_type {
> >   	 */
> >   	PERF_RECORD_SWITCH_CPU_WIDE		= 15,
> >   
> > +	/*
> > +	 * struct {
> > +	 *	struct perf_event_header	header;
> > +	 *
> > +	 *	u32				pid, tid;
> > +	 *	u64				time;
> pid,tid and time are already present in sample_id. Many of the 'legacy'
> record have redundant information since we added sample_id, but most of
> the new ones haven't and rely on sample_all being set.

I tried using pid/tid from sample data, but realized that pid/tid in 
event_id
could be different from the one in sample data, at least for fork/namespaces
events, since __perf_event_header__init_id( ) that updates the sample data
is getting the pid/tid of current task.

I am not sure if it is advisable to change __perf_event_header__init_id( 
) for this..?

Thanks
Hari