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From: Josh Triplett <>
To: Steven Rostedt <>
Subject: Re: [RFC 0/4] tracing,x86_64 - function/graph trace without mcount/-pg/framepointer
Date: Mon, 7 Feb 2011 13:22:22 -0800	[thread overview]
Message-ID: <20110207212220.GA30070@feather> (raw)

On Fri, Jun 23, 2000 at 10:56:55AM +0000, Steven Rostedt wrote:
> On Thu, 2011-02-03 at 16:42 +0100, Jiri Olsa wrote:
> > hi,
> > 
> > I recently saw the direct jump probing made for kprobes
> > and tried to use it inside the trace framework.
> > 
> > The global idea is patching the function entry with direct
> > jump to the trace code, instead of using pregenerated gcc
> > profile code.
> Interesting, but ideally, it would be nice if gcc provided a better
> "mcount" mechanism. One that calls mcount (or whatever new name it would
> have) before it does anything with the stack.

GCC 4.6 may help here.  According to

"Support for emitting profiler counter calls before function prologues.
This is enabled via a new command-line option -mfentry."

Looks like that option might only support x86 (32-bit and 64-bit) at the
moment, but it still seems like an improvement over the current
mechanism to work around GCC's placement of mcount.

- Josh Triplett

             reply	other threads:[~2011-02-07 21:22 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-02-07 21:22 Josh Triplett [this message]
2011-02-07 21:32 ` Steven Rostedt
  -- strict thread matches above, loose matches on Subject: below --
2011-02-03 15:42 Jiri Olsa
2011-02-03 16:33 ` Steven Rostedt
2011-02-03 17:35   ` Frederic Weisbecker
2011-02-03 19:00     ` Steven Rostedt
2011-02-04  6:03 ` Masami Hiramatsu

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