From: "Paul E. McKenney" <paulmck@kernel.org>
To: Joel Fernandes <joel@joelfernandes.org>
Cc: linux-kernel@vger.kernel.org,
Frederic Weisbecker <fweisbec@gmail.com>,
Jonathan Corbet <corbet@lwn.net>,
Josh Triplett <josh@joshtriplett.org>,
kernel-team@android.com, Lai Jiangshan <jiangshanlai@gmail.com>,
linux-doc@vger.kernel.org,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
rcu@vger.kernel.org, Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [RFC v1 2/2] rcu/tree: Remove dynticks_nmi_nesting counter
Date: Thu, 29 Aug 2019 09:32:55 -0700 [thread overview]
Message-ID: <20190829163255.GA15605@linux.ibm.com> (raw)
In-Reply-To: <20190829135907.GC63638@google.com>
On Thu, Aug 29, 2019 at 09:59:07AM -0400, Joel Fernandes wrote:
> On Wed, Aug 28, 2019 at 08:43:36PM -0700, Paul E. McKenney wrote:
> [snip]
> > On the tracing patch... That patch might be a good idea regardless,
> > but I bet that the reason that you felt the sudden need for it was due
> > to the loss of information in your eventual ->dynticks_nesting field.
> > After all, the value 0x1 might be an interrupt from idle, or it might
> > just as easily be a task running in the kernel at process level.
>
> True, however what really triggered me to do it was the existing code which
> does not distinguish between entry/exit from USER and IDLE.
>
> > The reason the patch might nevertheless be a good idea is that redundant
> > information can be helpful when debugging. Especially when debugging
> > new architecture-specific code, which is when RCU's dyntick-idle warnings
> > tend to find bugs.
>
> Sure, and also that it is more readable to ordinary human beings than "++="
> and "--=" :-D.
And those considerations did figure into my deciding that the tracing
change was likely a good thing in any case. ;-)
Thanx, Paul
next prev parent reply other threads:[~2019-08-29 16:33 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-27 1:33 [RFC v1 2/2] rcu/tree: Remove dynticks_nmi_nesting counter Joel Fernandes (Google)
2019-08-27 1:40 ` Joel Fernandes
2019-08-28 20:23 ` Paul E. McKenney
2019-08-28 21:05 ` Joel Fernandes
2019-08-28 21:19 ` Paul E. McKenney
2019-08-28 21:42 ` Joel Fernandes
2019-08-28 22:01 ` Paul E. McKenney
2019-08-28 22:14 ` Joel Fernandes
2019-08-28 23:12 ` Paul E. McKenney
2019-08-29 1:51 ` Joel Fernandes
2019-08-29 3:43 ` Paul E. McKenney
2019-08-29 13:59 ` Joel Fernandes
2019-08-29 16:32 ` Paul E. McKenney [this message]
2019-08-29 14:43 ` Joel Fernandes
2019-08-29 15:13 ` Joel Fernandes
2019-08-29 16:13 ` Paul E. McKenney
2019-08-29 17:14 ` Joel Fernandes
2019-08-30 0:47 ` Paul E. McKenney
2019-08-30 1:20 ` Joel Fernandes
2019-08-30 2:45 ` Paul E. McKenney
2019-08-29 16:09 ` Paul E. McKenney
2019-08-29 16:21 ` Andy Lutomirski
2019-08-29 16:54 ` Paul E. McKenney
2019-08-29 19:00 ` Joel Fernandes
2019-08-30 0:48 ` Paul E. McKenney
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