RCU Archive on lore.kernel.org
 help / color / Atom feed
From: "Paul E. McKenney" <paulmck@linux.ibm.com>
To: Joel Fernandes <joel@joelfernandes.org>
Cc: rcu@vger.kernel.org
Subject: Re: need_heavy_qs flag for PREEMPT=y kernels
Date: Mon, 12 Aug 2019 19:50:57 -0700
Message-ID: <20190813025057.GY28441@linux.ibm.com> (raw)
In-Reply-To: <20190813022726.GW28441@linux.ibm.com>

On Mon, Aug 12, 2019 at 07:27:26PM -0700, Paul E. McKenney wrote:
> On Mon, Aug 12, 2019 at 09:02:49PM -0400, Joel Fernandes wrote:
> > On Mon, Aug 12, 2019 at 04:01:38PM -0700, Paul E. McKenney wrote:

[ . . . ]

> > Instead of checking dynticks_nmi_nesting == 2 in rcu_nmi_exit_common(), can
> > we do the tick_dep_set_cpu(rdp->cpu, TICK_DEP_MASK_RCU)  from
> > rcu_nmi_enter_common() ? We could add this code there, under the "if
> > (rcu_dynticks_curr_cpu_in_eqs())".
> 
> It might well make sense to do this on entry, especially if doing so
> might safe an instruction or two.  It won't make the tick happen much
> faster, given that interrupts are disabled throughout the handler.
> 
> > I will test this patch tomorrow and let you know how it goes.
> 
> No need, it dies horribly and quickly with rcutorture.  Not exactly
> a surprise.  ;-)

And also not a surprise, due to a laughably stupid mistake...

							Thanx, Paul

  reply index

Thread overview: 31+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-11 18:08 Joel Fernandes
2019-08-11 18:34 ` Joel Fernandes
2019-08-11 21:16   ` Paul E. McKenney
2019-08-11 21:25     ` Joel Fernandes
2019-08-11 23:30       ` Paul E. McKenney
2019-08-12  1:24         ` Joel Fernandes
2019-08-12  1:40           ` Joel Fernandes
2019-08-12  3:57             ` Paul E. McKenney
2019-08-11 21:13 ` Paul E. McKenney
2019-08-12  3:21   ` Joel Fernandes
2019-08-12  3:53     ` Paul E. McKenney
2019-08-12 21:20       ` Joel Fernandes
2019-08-12 23:01         ` Paul E. McKenney
2019-08-13  1:02           ` Joel Fernandes
2019-08-13  1:05             ` Joel Fernandes
2019-08-13  2:28               ` Paul E. McKenney
2019-08-13  2:27             ` Paul E. McKenney
2019-08-13  2:50               ` Paul E. McKenney [this message]
2019-08-15 17:17             ` Paul E. McKenney
2019-08-15 20:04               ` Joel Fernandes
2019-08-15 20:31                 ` Paul E. McKenney
2019-08-15 21:22                   ` Joel Fernandes
2019-08-15 21:27                     ` Joel Fernandes
2019-08-15 21:34                       ` Joel Fernandes
2019-08-15 21:57                         ` Paul E. McKenney
2019-08-15 21:45                     ` Paul E. McKenney
2019-08-16  0:02                       ` Joel Fernandes
2019-08-19 12:34                         ` Frederic Weisbecker
2019-08-19 12:09                   ` Frederic Weisbecker
2019-08-19 16:57                   ` Frederic Weisbecker
2019-08-19 22:31                     ` Paul E. McKenney

Reply instructions:

You may reply publically 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=20190813025057.GY28441@linux.ibm.com \
    --to=paulmck@linux.ibm.com \
    --cc=joel@joelfernandes.org \
    --cc=rcu@vger.kernel.org \
    /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

RCU Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/rcu/0 rcu/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 rcu rcu/ https://lore.kernel.org/rcu \
		rcu@vger.kernel.org
	public-inbox-index rcu

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.rcu


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git