From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: linux-kernel@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Subject: Re: [PATCH 2/3] tracing: Move enabling tracepoints to just after mm_init()
Date: Sun, 14 Dec 2014 12:26:44 -0800 [thread overview]
Message-ID: <20141214202644.GI5310@linux.vnet.ibm.com> (raw)
In-Reply-To: <20141214132020.4ddf323b@gandalf.local.home>
On Sun, Dec 14, 2014 at 01:20:20PM -0500, Steven Rostedt wrote:
> On Sun, 14 Dec 2014 10:14:44 -0800
> "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> wrote:
>
>
> > > diff --git a/init/main.c b/init/main.c
> > > index 800a0daede7e..060e60b6aa59 100644
> > > --- a/init/main.c
> > > +++ b/init/main.c
> > > @@ -561,6 +561,9 @@ asmlinkage __visible void __init start_kernel(void)
> > > trap_init();
> > > mm_init();
> > >
> > > + /* trace_printk() and trace points may be used after this */
> > > + trace_init();
> >
> > Or if you aren't going to use call_rcu_sched() before this point, I could
> > move the call_rcu_sched()-relevant initialization to this point. Or make
> > the compiler do it -- I am pretty sure that the per-CPU variables are in
> > place at this point.
>
> Well, we could move trace_init() after rcu_init() for now too, and
> remove my tracepoint patch. But I'd like to have trace_init() go before
> sched_init() since that could possibly use debugging tracepoints as
> well.
>
> So if you could add a rcu_partial_init() that makes calling
> call_rcu_sched() work, that would be great. That could be for 3.20
> then, and for now, I just move trace_init() after rcu_init() which is
> still before irq_init() that Thomas needs for his work.
Sounds like a good approach. I also need to check up on documentation of
which RCU primitives can be used where, I suspect.
Thanx, Paul
next prev parent reply other threads:[~2014-12-14 20:27 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-12-14 16:41 [PATCH 0/3] tracing: Enable tracepoints early and allow printk to use them Steven Rostedt
2014-12-14 16:41 ` [PATCH 1/3] tracepoints: Do not use call_rcu_sched() before early_initcall() Steven Rostedt
2014-12-14 16:53 ` Steven Rostedt
2014-12-14 18:08 ` Paul E. McKenney
2014-12-14 18:15 ` Steven Rostedt
2014-12-14 18:18 ` Paul E. McKenney
2014-12-14 18:25 ` Steven Rostedt
2014-12-14 20:23 ` Paul E. McKenney
2014-12-14 17:05 ` Mathieu Desnoyers
2014-12-14 17:14 ` Steven Rostedt
2014-12-14 17:21 ` Steven Rostedt
2014-12-14 17:29 ` Mathieu Desnoyers
2014-12-14 17:44 ` Steven Rostedt
2014-12-14 18:13 ` Paul E. McKenney
2014-12-14 16:41 ` [PATCH 2/3] tracing: Move enabling tracepoints to just after mm_init() Steven Rostedt
2014-12-14 18:14 ` Paul E. McKenney
2014-12-14 18:20 ` Steven Rostedt
2014-12-14 20:26 ` Paul E. McKenney [this message]
2014-12-14 16:41 ` [PATCH 3/3] tracing: Add tp_printk cmdline to have tracepoints go to printk() Steven Rostedt
2014-12-14 17:07 ` [PATCH 0/3] tracing: Enable tracepoints early and allow printk to use them Steven Rostedt
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