Re: [PATCH 01/14] perf/x86: Introduce PERF_RECORD_OVERHEAD

[Jiri Olsa]

On Thu, Nov 24, 2016 at 02:39:26PM +0000, Liang, Kan wrote:
> 
> 
> > On Thu, Nov 24, 2016 at 01:56:51PM +0000, Liang, Kan wrote:
> > >
> > >
> > > >
> > > > On Thu, Nov 24, 2016 at 01:45:28PM +0000, Liang, Kan wrote:
> > > > > > I think we should make this optional/configurable like the rest
> > > > > > of the aux events, like below..
> > > > > >
> > > > >
> > > > > The overhead logging only happens when event is going to be
> > > > > disabled or the task is scheduling out. It should not be much and
> > expensive.
> > > > >
> > > > > Peter,
> > > > >
> > > > > What do you think?
> > > > > Should we make it configurable?
> > > >
> > > > Is there a downside to having it optional?
> > >
> > > NO. There will be no overhead information dumped into perf.data. Just
> > > like current implementation.
> > 
> > old perf tools will get unexpected events if it's not optional
> >
> 
> That's expected because a new record type is introduced.

but not if it's configurable.. older tools wont get it

jirka