Re: Too many PMC implementations

[Joerg Sonnenberger <joerg%bec.de@localhost>]

On Fri, Aug 17, 2018 at 04:20:30PM +0200, Maxime Villard wrote:
> Le 10/08/2018 à 11:40, Maxime Villard a écrit :
> > I saw the thread [Re: Sample based profiling] on tech-userlevel@, I'm not
> > subscribed to this list but I'm answering here because it's related to
> > tprof among other things.
> > 
> > I agree that it would be better to retire gprof in base, because there are
> > more powerful tools now, and also advanced hardware support (PMC, PEBS,
> > ProcessorTrace).
> > 
> > But in particular, it would be nice to retire the "kernel gprof". That is,
> > the MD/MI pieces that are surrounded by #ifdef GPROF. This kind of
> > profiling is weak, and misses many aspects of execution (branch prediction,
> > cache misses, heavy instructions, etc) that are offered by tprof.
> > 
> > I already dropped NENTRY() from x86, so KGPROF is officially not supported
> > there anymore. I think it has never worked on amd64.
> 
> So no one has any opinion on that? Because in this case I will remove it
> soon. (Talking about the kernel gprof.)

I'm quite reluctant to remove the only sample based profiler we have
right now. Esp. since we don't have any infrastructure for counter-based
profilers either AFAICT.

Joerg