Re: [RFC PATCH] LTTng relay buffer allocation, read, write

Steven Rostedt
2008-09-30T20:21:25Z

On Tue, 30 Sep 2008, Frank Ch. Eigler wrote:
> On Tue, Sep 30, 2008 at 03:43:45PM -0400, Steven Rostedt wrote:
> > [...]
> > On Tue, 30 Sep 2008, Mathieu Desnoyers wrote:
> > >
> > > You are actually using them to put redundant information that could be
> > > encoded differently and thus save 4 bits per event records, more or less
> > > what will be needed by most tracers (15 IDs, 1 reserved for an extended
> > > ID field).
> >
> > I really like the idea of keeping the tracer event ids out of the ring
> > buffer logic.
>
> That's fine for a ring buffer that only ever contains data from one
> event source. How do you imagine multiplexing working, where one
> wants to grep a single debugfs file that contains data from different
> event sources? Punt to another layer?

Field goal!

Yes! That is exactly what I want. If your trace has only one event, why
would it want to record them? The event id belongs in the tracer layer
not the ring buffer layer.

I would like to make a "trace_buffer" layer that includes all of this.

-- Steve