Re: [PATCH] rcu: update: make RCU_EXPEDITE_BOOT default

From	Josh Triplett <josh@joshtriplett.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH] rcu: update: make RCU_EXPEDITE_BOOT default
Date	2016-11-07 18:50 +0100
Message-ID	<sAWdr-6oY-29@gated-at.bofh.it> (permalink)
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On Mon, Nov 07, 2016 at 06:30:30PM +0100, Sebastian Andrzej Siewior wrote:
> On 2016-11-07 12:19:39 [-0500], Steven Rostedt wrote:
> > I agree, but if this creates a boot time regression in large machines,
> > it may not be warranted.
> > 
> > I know Linus usually doesn't like options with default y, but this may
> > be one of those exceptions. Perhaps we should make it on by default and
> > say in the config "if you have a machine with 100s or 1000s of CPUs,
> > you may want to disable this".
> 
> The default could change if we know where the limit is. I have access to
> a box with approx 140 CPUs so I could check there if it is already bad.
> But everything above that / in the 1000 range is a different story.

Right; if we can characterize what machines it benefits and what
machines it hurts, we can automatically detect and run the appropriate
case with no configuration option needed.

Thread

[PATCH] rcu: update: make RCU_EXPEDITE_BOOT default Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-02 17:40 +0100
  Re: [PATCH] rcu: update: make RCU_EXPEDITE_BOOT default "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-11-03 17:30 +0100
    Re: [PATCH] rcu: update: make RCU_EXPEDITE_BOOT default Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-03 17:40 +0100
      Re: [PATCH] rcu: update: make RCU_EXPEDITE_BOOT default "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-11-03 18:10 +0100
        Re: [PATCH] rcu: update: make RCU_EXPEDITE_BOOT default Steven Rostedt <rostedt@goodmis.org> - 2016-11-07 18:30 +0100
          Re: [PATCH] rcu: update: make RCU_EXPEDITE_BOOT default Sebastian Andrzej Siewior <bigeasy@linutronix.de> - 2016-11-07 18:40 +0100
            Re: [PATCH] rcu: update: make RCU_EXPEDITE_BOOT default Josh Triplett <josh@joshtriplett.org> - 2016-11-07 18:50 +0100
              Re: [PATCH] rcu: update: make RCU_EXPEDITE_BOOT default Josh Triplett <josh@joshtriplett.org> - 2016-11-07 19:10 +0100
                Re: [PATCH] rcu: update: make RCU_EXPEDITE_BOOT default "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-11-07 20:10 +0100
              Re: [PATCH] rcu: update: make RCU_EXPEDITE_BOOT default "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2016-11-07 19:40 +0100

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