Re: [PATCH v4 06/37] ring-buffer: Redefine the unimplemented RINGBUF_TYPE_TIME_STAMP

From: Tom Zanussi
Date: Mon Nov 06 2017 - 10:52:41 EST


Hi Namhyung,

On Mon, 2017-11-06 at 14:09 +0900, Namhyung Kim wrote:
> Hi Tom,
>
> On Mon, Oct 30, 2017 at 03:51:48PM -0500, Tom Zanussi wrote:
> > RINGBUF_TYPE_TIME_STAMP is defined but not used, and from what I can
> > gather was reserved for something like an absolute timestamp feature
> > for the ring buffer, if not a complete replacement of the current
> > time_delta scheme.
> >
> > This code redefines RINGBUF_TYPE_TIME_STAMP to implement absolute time
> > stamps. Another way to look at it is that it essentially forces
> > extended time_deltas for all events.
> >
> > The motivation for doing this is to enable time_deltas that aren't
> > dependent on previous events in the ring buffer, making it feasible to
> > use the ring_buffer_event timetamps in a more random-access way, for
> > purposes other than serial event printing.
> >
> > To set/reset this mode, use tracing_set_timestamp_abs() from the
> > previous interface patch.
> >
> > Signed-off-by: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx>
> > ---
>
> [SNIP]
> > @@ -2220,13 +2246,16 @@ static void rb_inc_iter(struct ring_buffer_iter *iter)
> > }
> >
> > /* Slow path, do not inline */
> > -static noinline struct ring_buffer_event *
> > +static struct noinline ring_buffer_event *
>
> struct noinline? Looks like a mistake..
>

Yeah, it is, not sure how that could have even happened, sheesh. Thanks
for pointing it out,

Tom