Re: [PATCH 08/12] add trace events for each syscall entry/exit

[Ingo Molnar <mingo@elte.hu>]

* Frederic Weisbecker <fweisbec@gmail.com> wrote:

> > +struct trace_event event_syscall_enter = {
> > +	.trace			= print_syscall_enter,
> > +	.type			= TRACE_SYSCALL_ENTER
> > +};
> > +
> > +struct trace_event event_syscall_exit = {
> > +	.trace			= print_syscall_exit,
> > +	.type			= TRACE_SYSCALL_EXIT
> > +};
> > -- 
> > 1.6.2.5
> > 
> 
> Nice.
> 
> It's a bit too bad that enter and exit must be that separated 
> whereas their callbacks are pretty the same.
> 
> But I guess if we want to nicely decouple both, we don't have the 
> choice.

Yeah - and enter and exit are different, in terms of state.

One thing that would be nice in the future (as an add-on - this 
patch-set looks useful already) is to allow the sampling of user 
register state as well via these tracepoints. That way we'd have a 
much faster (and completely transparent) implementation of strace in 
essence, with unique features such as system-wide or per cpu 
strace-ing.

	Ingo