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Re: [PATCH tip/core/rcu 04/18] rcu: Use single-stage IPI algorithm for RCU expedited grace period

From Peter Zijlstra <peterz@infradead.org>
Newsgroups linux.kernel
Subject Re: [PATCH tip/core/rcu 04/18] rcu: Use single-stage IPI algorithm for RCU expedited grace period
Date 2015-10-08 11:10 +0200
Message-ID <qhfn3-7oy-9@gated-at.bofh.it> (permalink)
References (1 earlier) <qgDhN-2Zi-29@gated-at.bofh.it> <qgDru-3aC-61@gated-at.bofh.it> <qgXgt-6rH-15@gated-at.bofh.it> <qgXgt-6rH-13@gated-at.bofh.it> <qgZBE-1xt-19@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Wed, Oct 07, 2015 at 09:14:45AM -0700, Paul E. McKenney wrote:
> On Wed, Oct 07, 2015 at 03:49:29PM +0200, Peter Zijlstra wrote:
> > On Wed, Oct 07, 2015 at 03:43:11PM +0200, Peter Zijlstra wrote:
> > > On Tue, Oct 06, 2015 at 09:29:23AM -0700, Paul E. McKenney wrote:
> > > > @@ -167,42 +307,18 @@ static void rcu_preempt_note_context_switch(void)
> > > 
> > > > -		raw_spin_unlock_irqrestore(&rnp->lock, flags);
> > > 
> > > This again reminds me that we should move rcu_note_context_switch()
> > > under the IRQ disable section the scheduler already has or remove the
> > > IRQ disable from rcu_note_context_switch().
> > 
> > Ah, this is the unlikely path where we actually need to do work. The
> > normal fast paths no longer require IRQs disabled, you already fixed
> > that last time, good!
> 
> But why not make the less-likely paths a bit cheaper while we are at it?  ;-)

True, less critical, but if we're almost there we might as well fix that
up too.
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[PATCH tip/core/rcu 0/18] Expedited grace-period improvements for 4.4 "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-06 18:30 +0200
  [PATCH tip/core/rcu 18/18] rcu: Better hotplug handling for synchronize_sched_expedited() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-06 18:40 +0200
    Re: [PATCH tip/core/rcu 18/18] rcu: Better hotplug handling for  synchronize_sched_expedited() Peter Zijlstra <peterz@infradead.org> - 2015-10-07 16:30 +0200
      Re: [PATCH tip/core/rcu 18/18] rcu: Better hotplug handling for  synchronize_sched_expedited() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-07 18:30 +0200
        Re: [PATCH tip/core/rcu 18/18] rcu: Better hotplug handling for  synchronize_sched_expedited() Peter Zijlstra <peterz@infradead.org> - 2015-10-08 11:10 +0200
          Re: [PATCH tip/core/rcu 18/18] rcu: Better hotplug handling for  synchronize_sched_expedited() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-08 17:10 +0200
            Re: [PATCH tip/core/rcu 18/18] rcu: Better hotplug handling for  synchronize_sched_expedited() Peter Zijlstra <peterz@infradead.org> - 2015-10-08 17:20 +0200
              Re: [PATCH tip/core/rcu 18/18] rcu: Better hotplug handling for  synchronize_sched_expedited() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-08 17:20 +0200
                Re: [PATCH tip/core/rcu 18/18] rcu: Better hotplug handling for  synchronize_sched_expedited() Josh Triplett <josh@joshtriplett.org> - 2015-10-08 20:10 +0200
                Re: [PATCH tip/core/rcu 18/18] rcu: Better hotplug handling for  synchronize_sched_expedited() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-09 02:20 +0200
                Re: [PATCH tip/core/rcu 18/18] rcu: Better hotplug handling for  synchronize_sched_expedited() Josh Triplett <josh@joshtriplett.org> - 2015-10-09 02:50 +0200
                Re: [PATCH tip/core/rcu 18/18] rcu: Better hotplug handling for  synchronize_sched_expedited() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-09 06:00 +0200
  [PATCH tip/core/rcu 10/18] rcu: Stop silencing lockdep false positive for expedited grace periods "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-06 18:40 +0200
  [PATCH tip/core/rcu 08/18] rcu: Make ->cpu_no_qs be a union for aggregate OR "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-06 18:40 +0200
  [PATCH tip/core/rcu 02/18] rcu: Move rcu_report_exp_rnp() to allow consolidation "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-06 18:40 +0200
    Re: [PATCH tip/core/rcu 02/18] rcu: Move rcu_report_exp_rnp() to  allow consolidation Peter Zijlstra <peterz@infradead.org> - 2015-10-06 22:30 +0200
      Re: [PATCH tip/core/rcu 02/18] rcu: Move rcu_report_exp_rnp() to  allow consolidation "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-06 23:00 +0200
        Re: [PATCH tip/core/rcu 02/18] rcu: Move rcu_report_exp_rnp() to  allow consolidation Peter Zijlstra <peterz@infradead.org> - 2015-10-07 10:00 +0200
          Re: [PATCH tip/core/rcu 02/18] rcu: Move rcu_report_exp_rnp() to  allow consolidation Mathieu Desnoyers <mathieu.desnoyers@efficios.com> - 2015-10-07 10:50 +0200
            Re: [PATCH tip/core/rcu 02/18] rcu: Move rcu_report_exp_rnp() to  allow consolidation Peter Zijlstra <peterz@infradead.org> - 2015-10-07 13:10 +0200
              Re: [PATCH tip/core/rcu 02/18] rcu: Move rcu_report_exp_rnp() to  allow consolidation Peter Zijlstra <peterz@infradead.org> - 2015-10-07 14:00 +0200
                Re: [PATCH tip/core/rcu 02/18] rcu: Move rcu_report_exp_rnp() to  allow consolidation Peter Zijlstra <peterz@infradead.org> - 2015-10-07 14:10 +0200
                Re: Re: [PATCH tip/core/rcu 02/18] rcu: Move rcu_report_exp_rnp() to  allow consolidation kbuild test robot <lkp@intel.com> - 2015-10-07 14:10 +0200
                Re: Re: [PATCH tip/core/rcu 02/18] rcu: Move rcu_report_exp_rnp() to  allow consolidation kbuild test robot <lkp@intel.com> - 2015-10-07 14:10 +0200
                Re: Re: [PATCH tip/core/rcu 02/18] rcu: Move rcu_report_exp_rnp() to  allow consolidation Peter Zijlstra <peterz@infradead.org> - 2015-10-07 14:20 +0200
                Re: [kbuild-all] [PATCH tip/core/rcu 02/18] rcu: Move  rcu_report_exp_rnp() to allow consolidation Fengguang Wu <lkp@intel.com> - 2015-10-07 15:50 +0200
                Re: [kbuild-all] [PATCH tip/core/rcu 02/18] rcu: Move  rcu_report_exp_rnp() to allow consolidation Peter Zijlstra <peterz@infradead.org> - 2015-10-07 16:00 +0200
                Re: [kbuild-all] [PATCH tip/core/rcu 02/18] rcu: Move  rcu_report_exp_rnp() to allow consolidation Peter Zijlstra <peterz@infradead.org> - 2015-10-07 16:30 +0200
                Re: [kbuild-all] [PATCH tip/core/rcu 02/18] rcu: Move  rcu_report_exp_rnp() to allow consolidation Fengguang Wu <lkp@intel.com> - 2015-10-07 16:30 +0200
                Re: Re: [PATCH tip/core/rcu 02/18] rcu: Move rcu_report_exp_rnp() to  allow consolidation kbuild test robot <lkp@intel.com> - 2015-10-07 14:20 +0200
                Re: [PATCH tip/core/rcu 02/18] rcu: Move rcu_report_exp_rnp() to  allow consolidation "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-07 17:20 +0200
                Re: [PATCH tip/core/rcu 02/18] rcu: Move rcu_report_exp_rnp() to  allow consolidation Peter Zijlstra <peterz@infradead.org> - 2015-10-08 12:30 +0200
              Re: [PATCH tip/core/rcu 02/18] rcu: Move rcu_report_exp_rnp() to  allow consolidation "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-07 17:20 +0200
          Re: [PATCH tip/core/rcu 02/18] rcu: Move rcu_report_exp_rnp() to  allow consolidation "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-07 16:40 +0200
            Re: [PATCH tip/core/rcu 02/18] rcu: Move rcu_report_exp_rnp() to  allow consolidation Peter Zijlstra <peterz@infradead.org> - 2015-10-07 16:50 +0200
              Re: [PATCH tip/core/rcu 02/18] rcu: Move rcu_report_exp_rnp() to  allow consolidation "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-07 18:50 +0200
                Re: [PATCH tip/core/rcu 02/18] rcu: Move rcu_report_exp_rnp() to  allow consolidation Peter Zijlstra <peterz@infradead.org> - 2015-10-08 11:50 +0200
                Re: [PATCH tip/core/rcu 02/18] rcu: Move rcu_report_exp_rnp() to  allow consolidation "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-08 17:40 +0200
                Re: [PATCH tip/core/rcu 02/18] rcu: Move rcu_report_exp_rnp() to  allow consolidation Peter Zijlstra <peterz@infradead.org> - 2015-10-08 19:20 +0200
                Re: [PATCH tip/core/rcu 02/18] rcu: Move rcu_report_exp_rnp() to  allow consolidation "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-08 19:50 +0200
                Re: [PATCH tip/core/rcu 02/18] rcu: Move rcu_report_exp_rnp() to  allow consolidation "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-09 02:20 +0200
                Re: [PATCH tip/core/rcu 02/18] rcu: Move rcu_report_exp_rnp() to  allow consolidation Peter Zijlstra <peterz@infradead.org> - 2015-10-09 10:50 +0200
  [PATCH tip/core/rcu 05/18] rcu: Move synchronize_sched_expedited() to combining tree "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-06 18:40 +0200
  [PATCH tip/core/rcu 16/18] rcu: Add tasks to expedited stall-warning messages "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-06 18:40 +0200
  [PATCH tip/core/rcu 12/18] cpu: Remove try_get_online_cpus() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-06 18:40 +0200
  [PATCH tip/core/rcu 03/18] rcu: Consolidate tree setup for synchronize_rcu_expedited() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-06 18:40 +0200
  [PATCH tip/core/rcu 13/18] rcu: Prepare for consolidating expedited CPU selection "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-06 18:40 +0200
  [PATCH tip/core/rcu 07/18] rcu: Invert passed_quiesce and rename to cpu_no_qs "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-06 18:40 +0200
  [PATCH tip/core/rcu 04/18] rcu: Use single-stage IPI algorithm for RCU expedited grace period "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-06 18:40 +0200
    Re: [PATCH tip/core/rcu 04/18] rcu: Use single-stage IPI algorithm  for RCU expedited grace period Peter Zijlstra <peterz@infradead.org> - 2015-10-07 15:30 +0200
      Re: [PATCH tip/core/rcu 04/18] rcu: Use single-stage IPI algorithm  for RCU expedited grace period "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-07 20:20 +0200
    Re: [PATCH tip/core/rcu 04/18] rcu: Use single-stage IPI algorithm  for RCU expedited grace period Peter Zijlstra <peterz@infradead.org> - 2015-10-07 15:40 +0200
      Re: [PATCH tip/core/rcu 04/18] rcu: Use single-stage IPI algorithm  for RCU expedited grace period "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-07 17:50 +0200
    Re: [PATCH tip/core/rcu 04/18] rcu: Use single-stage IPI algorithm  for RCU expedited grace period Peter Zijlstra <peterz@infradead.org> - 2015-10-07 15:50 +0200
      Re: [PATCH tip/core/rcu 04/18] rcu: Use single-stage IPI algorithm  for RCU expedited grace period "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-07 18:20 +0200
        Re: [PATCH tip/core/rcu 04/18] rcu: Use single-stage IPI algorithm  for RCU expedited grace period Peter Zijlstra <peterz@infradead.org> - 2015-10-08 11:10 +0200
    Re: [PATCH tip/core/rcu 04/18] rcu: Use single-stage IPI algorithm  for RCU expedited grace period Peter Zijlstra <peterz@infradead.org> - 2015-10-07 15:50 +0200
      Re: [PATCH tip/core/rcu 04/18] rcu: Use single-stage IPI algorithm  for RCU expedited grace period "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-07 18:20 +0200
  [PATCH tip/core/rcu 09/18] rcu: Switch synchronize_sched_expedited() to IPI "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-06 18:40 +0200
    Re: [PATCH tip/core/rcu 09/18] rcu: Switch  synchronize_sched_expedited() to IPI Peter Zijlstra <peterz@infradead.org> - 2015-10-07 16:20 +0200
      Re: [PATCH tip/core/rcu 09/18] rcu: Switch  synchronize_sched_expedited() to IPI "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-07 18:30 +0200
  [PATCH tip/core/rcu 15/18] rcu: Add online/offline info to expedited stall warning message "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-06 18:40 +0200
  [PATCH tip/core/rcu 14/18] rcu: Consolidate expedited CPU selection "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-06 18:40 +0200
  [PATCH tip/core/rcu 01/18] rcu: Use rsp->expedited_wq instead of sync_rcu_preempt_exp_wq "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-06 18:40 +0200
    [PATCH tip/core/rcu 06/18] rcu: Rename qs_pending to core_needs_qs "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-06 18:40 +0200
    [PATCH tip/core/rcu 17/18] rcu: Enable stall warnings for synchronize_rcu_expedited() "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-06 18:40 +0200

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