[PATCH RFC] powerpc/ftrace: add powerpc timebase as a trace clock source

[Steven Rostedt]

On Tue, 21 Apr 2015 16:33:36 +0530
"Naveen N. Rao" <naveen.n.rao at linux.vnet.ibm.com> wrote:

> Add a new powerpc-specific trace clock using the timebase register,
> similar to x86-tsc. This gives us a fast, monotonic, cross-cpu clock
> for trace entries and can be used to correlate events across cpus as
> well as across hypervisor and guest (assuming it is not a migrated guest
> with a non-zero tb_offset).
> 
> Signed-off-by: Naveen N. Rao <naveen.n.rao at linux.vnet.ibm.com>
> ---
> I have followed the approach used by x86-tsc here, but we could get rid of
> trace_clock.c if we directly use get_tb() with perhaps the notrace annotation.
> Would that be preferable?
> 

Probably. But all clocks used by tracing should be marked by notrace.
Don't just wrap it with a notrace. But looking at the code, it seems
that get_tb() is a static inline, which wont work as a pointer. Seems
you still need the indirect function call.

Note, all "inline" functions are notrace by default, so you do not need
to add any notrace annotation to an inlined function.

-- Steve