From: Jiri Olsa <jolsa@redhat.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH] ftrace: Remove use of control list and ops
Date: Tue, 1 Dec 2015 16:57:44 +0100 [thread overview]
Message-ID: <20151201155744.GA24786@krava.local> (raw)
In-Reply-To: <20151201095554.7b56bff7@gandalf.local.home>
On Tue, Dec 01, 2015 at 09:55:54AM -0500, Steven Rostedt wrote:
> On Tue, 1 Dec 2015 14:42:36 +0100
> Jiri Olsa <jolsa@redhat.com> wrote:
>
> > On Mon, Nov 30, 2015 at 05:36:40PM -0500, Steven Rostedt wrote:
> > >
> > > [ Jiri, can you take a look at this. You can also apply it on top of my
> > > branch ftrace/core, and run any specific tests. I just need to nuke
> > > that control structure for further updates with ftrace. ]
> > >
> > >
> > > Currently perf has its own list function within the ftrace infrastructure
> > > that seems to be used only to allow for it to have per-cpu disabling as well
> > > as a check to make sure that it's not called while RCU is not watching. It
> > > uses something called the "control_ops" which is used to iterate over ops
> > > under it with the control_list_func().
> > >
> > > The problem is that this control_ops and control_list_func unnecessarily
> > > complicates the code. By replacing FTRACE_OPS_FL_CONTROL with two new flags
> > > (FTRACE_OPS_FL_RCU and FTRACE_OPS_FL_PER_CPU) we can remove all the code
> > > that is special with the control ops and add the needed checks within the
> > > generic ftrace_list_func().
> >
> > hum,
> > do we need also change for the trampoline, something like below?
> >
> > I needed attached patch to get the perf ftrace:function
> > event work properly..
>
> Hmm, I thought that I forced the list function when RCU or PER_CPU
> was set. Oh wait. I have CONFIG_PREEMPT set, which will change the
> logic slightly. I'm guessing you have PREEMPT_VOLUNTARY set. I'll try
> that out.
yep, but the trampoline has separate code path
to set the ops func
jirka
next prev parent reply other threads:[~2015-12-01 15:57 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-11-30 22:36 [PATCH] ftrace: Remove use of control list and ops Steven Rostedt
2015-12-01 13:42 ` Jiri Olsa
2015-12-01 14:55 ` Steven Rostedt
2015-12-01 15:57 ` Jiri Olsa [this message]
2015-12-01 16:56 ` Steven Rostedt
2015-12-02 7:59 ` Jiri Olsa
2015-12-02 14:15 ` Steven Rostedt
2015-12-02 8:58 ` Jiri Olsa
2015-12-02 14:27 ` Steven Rostedt
2015-12-02 14:50 ` Jiri Olsa
2015-12-02 15:03 ` Steven Rostedt
2015-12-02 15:23 ` Jiri Olsa
2015-12-18 10:18 ` Jiri Olsa
2015-12-18 14:35 ` Steven Rostedt
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