* Adrian Hunter <adrian.hun...@intel.com> wrote:
> On 15/11/13 13:10, Ingo Molnar wrote:
> >
> > * Adrian Hunter <adrian.hun...@intel.com> wrote:
> >
> >>> And I also raised why this shouldn't be the default event tracing
> >>> method instead of a weird config option. Per-cpu tracing is cache
> >>> compact, it is easier to size properly and in general it is pretty
> >>> easy to think about. (It also has less of the TSC timestamp
> >>> ordering problems as per thread tracing, at least in theory.)
> >>>
> >>> Is there something that makes per cpu tracing undesirable as the
> >>> default?
> >>
> >> One reason is to avoid changing the meaning of existing options.
> >
> > Well, the way the tracing buffers are set up is a mostly tool internal
> > matter so in that sense it should be just fine to change the default
> > behavior - as long as output remains unchanged (which it should).
> >
> > Or is there any material change in behavior somewhere?
>
> Inheritance is enabled automatically with per-cpu mmaps,
> although that is one of the reasons people want
> per-cpu mmaps.
So, here's the current status quo, there's 4 basic types of profiling
that 99% of the people are using, in order of popularity:
perf record <cmd>
perf record -a sleep N
perf record -p <PID>
perf record -t <TID>
The first two (which I'd guess comprise about 95% of real-world usage)
have inheritance enabled.
The last two (-p/-t) have inheritance disabled by default.
Correct?
Thanks,
Ingo
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