Re: [PATCH RFC 0/3] Static calls

From: Josh Poimboeuf
Date: Fri Nov 09 2018 - 11:41:44 EST


On Fri, Nov 09, 2018 at 09:21:39AM -0600, Josh Poimboeuf wrote:
> On Fri, Nov 09, 2018 at 07:16:17AM -0800, Andy Lutomirski wrote:
> > On Thu, Nov 8, 2018 at 11:28 PM Ingo Molnar <mingo@xxxxxxxxxx> wrote:
> > >
> > >
> > > All other usecases are bonus, but it would certainly be interesting to
> > > investigate the impact of using these APIs for tracing: that too is a
> > > feature enabled everywhere but utilized only by a small fraction of Linux
> > > users - so literally every single cycle or instruction saved or hot-path
> > > shortened is a major win.
> >
> > For tracing, we'd want static_call_set_to_nop() or something like that, right?
>
> Are we talking about tracepoints? Or ftrace?

Since ftrace changes calls to nops, and vice versa, I assume you meant
ftrace. I don't think ftrace is a good candidate for this, as it's
inherently more flexible than this API would reasonably allow.

--
Josh