Re: [tip:perf/core] perf/ftrace: Optimize perf/tracepoint interaction for single events

Frederic Weisbecker
2010-05-19T08:23:35Z

On Wed, May 19, 2010 at 10:18:43AM +0200, Peter Zijlstra wrote:
> On Wed, 2010-05-19 at 09:58 +0200, Frederic Weisbecker wrote:
> > On Tue, May 18, 2010 at 05:15:42PM +0000, tip-bot for Peter Zijlstra wrote:
> > > Commit-ID: 4f41c013f553957765902fb01475972f0af3e8e7
> > > Gitweb: http://git.kernel.org/tip/4f41c013f553957765902fb01475972f0af3e8e7
> > > Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
> > > AuthorDate: Tue, 18 May 2010 18:08:32 +0200
> > > Committer: Ingo Molnar <mingo@elte.hu>
> > > CommitDate: Tue, 18 May 2010 18:35:46 +0200
> > >
> > > perf/ftrace: Optimize perf/tracepoint interaction for single events
> > >
> > > When we've got but a single event per tracepoint
> > > there is no reason to try and multiplex it so don't.
> > >
>
> > I haven't seen this patch going.
> >
> > But yeah that's a nice optimization for UP machines.
>
> Uhm, doesn't have anything to do with UP machines... it works quite well
> on SMP as well.
>
> Its about tracepoints with a single event attached.

Yeah, then if you launch perf sched for example, you'll have NR_CPU perf events
attached to each lock trace events, since we create one event per cpu.

Or may be I'm somewhat confused...