On Tue, 20 Apr 2021 09:29:27 -0400 (EDT) Mathieu Desnoyers <mathieu.desnoy...@efficios.com> wrote:
> ----- On Apr 20, 2021, at 8:55 AM, rostedt rost...@goodmis.org wrote: > [...] > > > > Would adding automatic module parameters be an issue? That is, you can add > > in the insmod command line a parameter that will enable tracepoints. We > > could have a way to even see them from the modinfo. I think I had that > > working once, and it wasn't really that hard to do. > > There is one thing we should consider here in terms of namespacing: those > module > command line parameters should be specific to each tracer (e.g. ftrace, perf, > ebpf). > > LTTng for instance already tackles early module load tracing in a different > way: users can enable instrumentation of yet-to-be loaded kernel modules. So > it would not make sense in that scheme to have module load parameters. > > It's a different trade-off in terms of error reporting though: for instance, > LTTng won't report an error if a user does a typo when entering an event name. > > So I think those command line parameters should be tracer-specific, do you > agree ? No, I do not agree. I would like to make it consistent with the kernel command line. As you can put in: "trace_event=sched_switch" and the sched_switch trace point will be enable (for the tracefs directory) on boot up. The same should be for modules as well. It shouldn't affect LTTng, as you already have a way to enable them as they get loaded. -- Steve
