LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Joel Fernandes <joelaf@google.com>,
	Namhyung Kim <namhyung@kernel.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	linux-kernel <linux-kernel@vger.kernel.org>,
	linux-rt-users <linux-rt-users@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>,
	Tom Zanussi <tom.zanussi@linux.intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Boqun Feng <boqun.feng@gmail.com>, fweisbec <fweisbec@gmail.com>,
	Randy Dunlap <rdunlap@infradead.org>,
	kbuild test robot <fengguang.wu@intel.com>,
	baohong liu <baohong.liu@intel.com>,
	vedang patel <vedang.patel@intel.com>,
	kernel-team <kernel-team@lge.com>
Subject: Re: [RFC v4 3/4] irqflags: Avoid unnecessary calls to trace_ if you can
Date: Tue, 24 Apr 2018 08:56:55 -0700	[thread overview]
Message-ID: <20180424155655.GA820@linux.vnet.ibm.com> (raw)
In-Reply-To: <20180423172244.694dbc9d@gandalf.local.home>

On Mon, Apr 23, 2018 at 05:22:44PM -0400, Steven Rostedt wrote:
> On Mon, 23 Apr 2018 13:12:21 -0400 (EDT)
> Mathieu Desnoyers <mathieu.desnoyers@efficios.com> wrote:
> 
> 
> > I'm inclined to explicitly declare the tracepoints with their given
> > synchronization method. Tracepoint probe callback functions for currently
> > existing tracepoints expect to have preemption disabled when invoked.
> > This assumption will not be true anymore for srcu-tracepoints.
> 
> Actually, why not have a flag attached to the tracepoint_func that
> states if it expects preemption to be enabled or not? If a
> trace_##event##_srcu() is called, then simply disable preemption before
> calling the callbacks for it. That way if a callback is fine for use
> with srcu, then it would require calling
> 
> 	register_trace_##event##_may_sleep();
> 
> Then if someone uses this on a tracepoint where preemption is disabled,
> we simply do not call it.

One more stupid question...  If we are having to trace so much stuff
in the idle loop, are we perhaps grossly overstating the extent of that
"idle" loop?  For being called "idle", this code seems quite busy!

							Thanx, Paul

  reply	other threads:[~2018-04-24 15:55 UTC|newest]

Thread overview: 44+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-17  4:07 [RFC v4 0/4] Centralize and unify usage of preempt/irq tracepoints Joel Fernandes
2018-04-17  4:07 ` [RFC v4 1/4] tracepoint: Add API to not do lockdep checks during RCU ops Joel Fernandes
2018-04-17  4:07 ` [RFC v4 2/4] softirq: reorder trace_softirqs_on to prevent lockdep splat Joel Fernandes
2018-04-17  4:07 ` [RFC v4 3/4] irqflags: Avoid unnecessary calls to trace_ if you can Joel Fernandes
2018-04-18  9:02   ` Masami Hiramatsu
2018-04-19  5:43     ` Namhyung Kim
2018-04-20  7:07       ` Joel Fernandes
2018-04-23  1:14         ` Joel Fernandes
2018-04-23  3:19           ` Paul E. McKenney
2018-04-23 14:31             ` Mathieu Desnoyers
2018-04-23 14:53               ` Steven Rostedt
2018-04-23 14:59                 ` Mathieu Desnoyers
2018-04-23 15:12                   ` Paul E. McKenney
2018-04-23 16:18                   ` Steven Rostedt
2018-04-23 17:12                     ` Mathieu Desnoyers
2018-04-23 17:24                       ` Joel Fernandes
2018-04-23 21:22                       ` Steven Rostedt
2018-04-24 15:56                         ` Paul E. McKenney [this message]
2018-04-24 16:01                           ` Joel Fernandes
2018-04-24 17:26                             ` Paul E. McKenney
2018-04-24 18:23                               ` Paul E. McKenney
2018-04-24 18:26                                 ` Paul E. McKenney
2018-04-24 18:59                                   ` Joel Fernandes
2018-04-24 19:01                                     ` Joel Fernandes
2018-04-24 19:09                                     ` Paul E. McKenney
2018-04-24 19:16                                       ` Joel Fernandes
2018-04-24 23:21                                     ` Mathieu Desnoyers
2018-04-24 23:46                                       ` Joel Fernandes
2018-04-25  0:10                                         ` Paul E. McKenney
2018-04-25  4:20                                           ` Paul E. McKenney
2018-04-25 21:27                                             ` Joel Fernandes
2018-04-25 21:35                                               ` Paul E. McKenney
2018-04-25 21:40                                               ` Mathieu Desnoyers
2018-04-25 22:51                                                 ` Steven Rostedt
2018-04-26 15:03                                                   ` Mathieu Desnoyers
2018-04-26 16:08                                                     ` Mathieu Desnoyers
2018-04-25 23:13                                                 ` Joel Fernandes
2018-04-26 15:13                                                   ` Mathieu Desnoyers
2018-04-26 15:20                                                     ` Joel Fernandes
2018-04-26 15:49                                                     ` Paul E. McKenney
2018-04-23 15:49                 ` Joel Fernandes
2018-04-26  2:18             ` Joel Fernandes
2018-05-01  1:18     ` Joel Fernandes
2018-04-17  4:07 ` [RFC v4 4/4] tracing: Centralize preemptirq tracepoints and unify their usage Joel Fernandes

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20180424155655.GA820@linux.vnet.ibm.com \
    --to=paulmck@linux.vnet.ibm.com \
    --cc=baohong.liu@intel.com \
    --cc=boqun.feng@gmail.com \
    --cc=fengguang.wu@intel.com \
    --cc=fweisbec@gmail.com \
    --cc=joelaf@google.com \
    --cc=kernel-team@lge.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-rt-users@vger.kernel.org \
    --cc=mathieu.desnoyers@efficios.com \
    --cc=mhiramat@kernel.org \
    --cc=mingo@redhat.com \
    --cc=namhyung@kernel.org \
    --cc=peterz@infradead.org \
    --cc=rdunlap@infradead.org \
    --cc=rostedt@goodmis.org \
    --cc=tglx@linutronix.de \
    --cc=tom.zanussi@linux.intel.com \
    --cc=vedang.patel@intel.com \
    --subject='Re: [RFC v4 3/4] irqflags: Avoid unnecessary calls to trace_ if you can' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).