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Date: Wed, 18 Jan 2012 10:39:44 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Oleg Nesterov <oleg@redhat.com>, Steven Rostedt <rostedt@goodmis.org>,
        Ingo Molnar <mingo@redhat.com>, Masami Hiramatsu <mhiramat@redhat.com>,
        Seiji Aguchi <saguchi@redhat.com>, linux-kernel@vger.kernel.org,
        Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Subject: Re: [GIT PULL] tracing: make signal tracepoints more useful
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* Linus Torvalds <torvalds@linux-foundation.org> wrote:

> On Mon, Jan 16, 2012 at 7:10 AM, Oleg Nesterov <oleg@redhat.com> wrote:
> >
> > But do we really need to keep the old tracepoint? IOW, what 
> > if we simply rename it and add more info?
> 
> Quite frankly, unless somebody can point to something that 
> breaks, I'd rather just change the existing one.
> 
> Nobody outside of a few special cases uses tracepoints. 
> *nobody*.  The only apps I have ever seen that matters to 
> anybody ends up being latencytop and powertop. If those two 
> have been tested and don't care, I don't think we should care.

Correct. (There's also sysprof and perf - both should be fine.)

As i said in my very first mail:

> [...] Which apps/tools rely on the old tracepoint? If it's 
> exactly zero apps then we might be able to change it, but this 
> needs to be investigated.

I resisted Steve's "this ABI change is safe by design" notion 
which is somewhat of a disease. It is probably fine but not by 
definition.

Thanks,

	Ingo