On Mon, 23 Nov 2015 17:28:05 +0900
Joonsoo Kim [off-list ref] wrote:

On Fri, Nov 20, 2015 at 11:42:25AM -0500, Steven Rostedt wrote:

quoted

On Fri, 20 Nov 2015 15:33:25 +0900
Joonsoo Kim [off-list ref] wrote:

  

quoted

Steven, is it possible to add tracepoint to inlined fucntion such as
get_page() in include/linux/mm.h?  

I highly recommend against it. The tracepoint code adds a bit of bloat,
and if you inline it, you add that bloat to every use case. Also, it  

Is it worse than adding function call to my own stub function into
inlined function such as get_page(). I implemented it as following.

get_page()
{
        atomic_inc()
        stub_get_page()
}

stub_get_page() in foo.c
{
        trace_page_ref_get_page()
}

Now you just slowed down the fast path. But what you could do is:

get_page()
{
	atomic_inc();
	if (trace_page_ref_get_page_enabled())
		stub_get_page();
}

Now that "trace_page_ref_get_page_enabled()" will turn into:

	if (static_key_false(&__tracepoint_page_ref_get_page.key)) {

which is a jump label (nop when disabled, a jmp when enabled). That's
less bloat but doesn't solve the include problem. You still need to add
the include of that will cause havoc with other tracepoints.

-- Steve