Re: [RFC] BTS based perf user callchains

Peter Zijlstra
2010-08-02T19:47:25Z

On Mon, 2010-08-02 at 20:41 +0200, Frederic Weisbecker wrote:
> On Mon, Aug 02, 2010 at 08:38:52PM +0200, Peter Zijlstra wrote:
> > On Mon, 2010-08-02 at 20:35 +0200, Frederic Weisbecker wrote:
> > > I'm not even sure that will work. Also, while looking at the BTS implementation
> > > in perf, I see we have one BTS buffer per cpu. But that doesn't look right as
> > > the code flow is not linear per cpu but per task. Hence I suspect we need
> > > one BTS buffer per task. But may be someone tried that and encountered a
> > > problem?
> >
> > IIRC we flush the buffer when we deschedule the counter.
>
>
> Ok. So the buffer is cut on schedule time. It might be nice
> to maintain the buffer progress across scheduling.

We flush it into the perf data buffer.