Re: [RFC PATCHSET] sched,perf: unify tracers in sched and move perf on top of TP

Paul Mackerras
2010-05-10T05:22:40Z

On Wed, May 05, 2010 at 11:54:52AM +0200, Tejun Heo wrote:

> On 05/05/2010 11:51 AM, Peter Zijlstra wrote:
> >> I was wondering the other way around - ie. the possibility to make
> >> perf optional and maybe even as a module which depends on TPs, which
> >> would be nicer than the current situation and make the code less
> >> cluttered too.
> >
> > I really really hate making perf rely on tracepoints.
>
> Hmmm.... may I ask why? Unifying hooking mechanism seems like a good
> idea to me and it's not like it's gonna add any runtime overhead
> although it does complicate init/exit but well that's something you
> have to pay if you wanna do things dynamically and sans the ifdef
> stuff it's like a couple hundred lines of isolated code.

Don't forget where perf_events started out - as a way to count and
record hardware events. So perf_events is very useful even in a
kernel that has no tracing infrastructure configured in at all.

Paul.