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SubjectRe: [PATCH 2/2] tracing/fastboot: Use the ring-buffer timestamp for initcall entries

* Steven Rostedt <rostedt@goodmis.org> wrote:

>
> On Wed, 12 Nov 2008, Ingo Molnar wrote:
>
> >
> > * Frederic Weisbecker <fweisbec@gmail.com> wrote:
> >
> > > Impact: Split the boot tracer entries in two parts: call and return
> > >
> > > Now that we are using the sched tracer from the boot tracer, we want
> > > to use the same timestamp than the ring-buffer to have consistent
> > > time captures between sched events and initcall events. So we get
> > > rid of the old time capture by the boot tracer and split the
> > > initcall events in two parts: call and return. This way we have the
> > > ring buffer timestamp of both.
> > >
> > > There is an example of a trace in attachment.
> > >
> > > Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
> > > ---
> > > include/trace/boot.h | 31 ++++++++---
> > > init/main.c | 32 ++++++------
> > > kernel/trace/trace.h | 17 ++++--
> > > kernel/trace/trace_boot.c | 123 ++++++++++++++++++++++++++++++++++-----------
> > > 4 files changed, 144 insertions(+), 59 deletions(-)
> >
> > applied to tip/tracing/fastboot, thanks Frederic!
> >
> > one small detail, do we need these messages in the boot tracer:
> >
> > ##### CPU 1 buffer started ####
> >
> > they are helpful for latency traces but might be confusing for boot
> > traces. (they lose their attraction after having seen a dozen of them)
>
> Yeah, I was thinking of putting in a iter_ctrl to disable them. But
> then, should they be on or off by default?
>
> The pro for having them off by default, they are not as distracting.
>
> The con for having them off by default, they lose their meaning, and
> developers get confused when they see CPU 1 starting after 100
> prints of CPU0, when they both should have started.

i think they are useful to be included for most of the tracers, except
the boot tracer (which starts/stop with high frequency). So i'd
suggest to keep the default, but also to expose it in an iter_ctl plus
dynamically turn it off for the boot tracer.

Ingo


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