Re: PATCH [0/4] perf: clean-up of power events API

Steven Rostedt
2010-10-09T21:34:58Z

On Sat, 2010-10-09 at 09:19 -0700, Arjan van de Ven wrote:

> > I.e. it's not an ABI in the classic sense - we do not (because we
> > cannot) guarantee the infinite availability of these events. But we can
> > guarantee that the fields do not change in some stupid, avoidable way.
>
> also I have to say that some events are more likely to change than others
>
> "function foo in the kernel called" is more likely to change than "the
> processor went to THIS frequency".
> The concept of CPU frequencies has been with us fora long time and is
> going to be there for a long time as well ......

Perhaps for basic concepts, we need a standard trace-event. Are people
willing to have a TRACE_EVENT_ABI() (it's trivial to write), and we can
mark those events with that macro that we know tools depend on.

These events can be exposed in a /sys/kernel/events/... directory, to
let tools know what what events they can rely on.

We've talked about doing this before, I've just been waiting to hear a
consensus on if we should. I know Peter Zijlstra was against the idea,
and too bad he's off gallivanting to share his input now.

-- Steve