Re: [RFC][PATCH 2/3] perf: Take a hot regs snapshot for trace events

[Frederic Weisbecker <fweisbec@gmail.com>]

On Wed, Mar 03, 2010 at 12:45:55PM -0500, Steven Rostedt wrote:
> On Wed, 2010-03-03 at 18:16 +0100, Peter Zijlstra wrote:
> 
> > > This is what I actually was wondering about. Why is it a "perf only"
> > > trace point instead of a TRACE_EVENT()?
> > 
> > Because I wanted to make perf usable without having to rely on funny
> > tracepoints. That is, I am less worried about committing software
> > counters to ABI than I am about TRACE_EVENT(), which still gives me a
> > terribly uncomfortable feeling.
> > 
> > Also, building with all CONFIG_TRACE_*=n will still yield a usable perf,
> > which is something the embedded people might fancy, all that TRACE stuff
> > adds lots of code.
> 
> We could make TRACE_EVENT() into a perf only trace point with
> CONFIG_TRACE_*=n. 



Yeah.


 
> Just saying that it would be nice if ftrace could also see page faults
> and such.


Agreed, we could make it a TRACE_EVENT. IIRC, someone proposed patches
for that by the past.

That notwithstanding one of the main worries is the fact TRACE_EVENT
are less ABI-stable guaranteed.