Re: [RFC] The New and Improved Logdev (now with kprobes!)

[Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>]

* Steven Rostedt (rostedt@goodmis.org) wrote:
 >
> > Please don't :) Defining a new event would be to say :
> >
> > I want to create an event named "schedchange", which belongs to the "kernel"
> > subsystem. In its definition, I say that it will take two integers and a long,
> > respectively names "prev_pid", "next_pid" and "state".
> >
> > We can think of various events for various subsystems, and even for modules. It
> > becomes interesting to have dynamically loadable event definitions which gets
> > loaded with kernel modules. The "description" of the events is saved in the
> > trace, in a special low traffic channel (small buffers with a separate file).
> >
> 
> But these events still need the marker in the source code right?
> 

Yes, but not necessarily. But it could also be a kernel module built
on-the-fly by a generator like SystemTAP which defines new events.

> 
> That should definitely be a step. If I'm understanding this (which I may
> not be), you can have a dynamic event added with also using dynamic
> trace points like kprobes.
> 

Yes, we could use a kprobes based approach with only one data type (string is
always a good example), but we could also define one specific event and its
associates data types for each probes.


> No prob, I should read the rest of the thread, and try to catch up more,
> before posting more comments.
> 

No problem, constructive comments and ideas are always welcome.


Mathieu

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