From: Christian Ludwig <christian_ludwig@genua.de>
Subject: Re: dt: Trace tracing program
To: "mpi@openbsd.org" <mpi@openbsd.org>
Cc: "tech@openbsd.org" <tech@openbsd.org>
Date: Fri, 16 Feb 2024 15:21:46 +0000

Hi,

sorry for the late reply.

On Mon, 2024-02-05 at 16:14 +0100, Martin Pieuchot wrote:
> On 02/02/24(Fri) 16:24, Christian Ludwig wrote:
> > For the sake of visibility, also trace the tracing program itself.
> > If you really wanted to hide it, add a filter to your probes, like:
> 
> I'm not sure about that.  Why do you want to see the tracing program?
> What are you trying to monitor?

I am trying to monitor interrupt events using the TRACEPOINT macro. But
in the current form, the TRACEPOINT macro simply ignores the tracing
program, which leads to seemingly "lost" interrupts. Hence the diff.

I think it's not worth adding another macro, TRACEPOINT does everything
I need, once it's adapted to be safe to call in all interrupt contexts.
I am working on that.

OTOH exposing the tracing program also makes it easier to better
connect the dots concering side effects introduced by the tracer. And
if you really want to hide it you can use a filter explicitly.

So long,


 - Christian