Messages in this thread | | | Date | Fri, 17 Aug 2012 11:04:07 -0300 | Subject | Re: [RFC PATCH 1/1] trace: Move trace event enable from fs_initcall to early_initcall | From | Ezequiel Garcia <> |
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On Fri, Aug 17, 2012 at 10:55 AM, Steven Rostedt <rostedt@goodmis.org> wrote: > On Fri, 2012-08-17 at 08:01 -0300, Ezequiel Garcia wrote: > >> Regarding the 'complete solution': to be able to capture events from >> the very beggining... >> Have you thought about this? >> Could you give me a hint on how could I implement it? > > How far in the "beginning"? Before memory is set up?
Yes.
> I wouldn't do that.
Yeah, perhaps it sounds crazy. It makes some sense for kmem events, though.
> I have in the past (set up before memory was finished being > initialized), but things have changed since then. > > One thing that we could do for those that want really early tracing, is > to add a config option to add a static temporary ring buffer, that gets
Yes, something like this would be ideal. How would this ring buffer be allocated? Perhaps as static and __initdata? This way it would be released afterwards, right?
> copied into the default ring buffer after memory is set up. That may be > the easiest way. > > Once memory is set up, the ring buffer can be allocated and events can > be traced, but the ring buffer needs to be set up first. All it would > take is some calls in init/main.c start_kernel() to the initialization. >
Note that my main concern is on trace_events (kmem events to be precise). However this are registered through tracepoints and in turn this tracepoints depend on kmalloc and friends. So, right now is a chicken-egg problem.
Thanks, Ezequiel.
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