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Re: [PATCH 2/4] timer: relax tick stop in idle entry

From Jacob Pan <jacob.jun.pan@linux.intel.com>
Newsgroups linux.kernel
Subject Re: [PATCH 2/4] timer: relax tick stop in idle entry
Date 2015-11-17 01:20 +0100
Message-ID <qvCa6-5Wu-7@gated-at.bofh.it> (permalink)
References (2 earlier) <qut8T-2FM-15@gated-at.bofh.it> <quv0Z-3RA-11@gated-at.bofh.it> <qvtzQ-sT-25@gated-at.bofh.it> <qvzYB-4nO-5@gated-at.bofh.it> <qvA8i-4Gl-21@gated-at.bofh.it>
Organization OTC

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On Mon, 16 Nov 2015 23:01:12 +0100 (CET)
Thomas Gleixner <tglx@linutronix.de> wrote:

> > For the second case, which is much more rare, I think we do have
> > next timer exactly one tick away. Just don't know why tick will
> > continue into idle loop.  
> 
> Well, it should not be hard to figure that out. There are not so many
> checks involved when tick_nohz_irq_exit() is called.
Thanks for the tip, I found the cause is in 
int idle_cpu(int cpu)
{
	if (rq->nr_running)
		return 0;

Since we only take into account of cfs_rq runnable taking over
cfs_rq->nr_running when forced_idle is set.


Jacob
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Thread

Re: [PATCH 2/4] timer: relax tick stop in idle entry Thomas Gleixner <tglx@linutronix.de> - 2015-11-16 16:10 +0100
  Re: [PATCH 2/4] timer: relax tick stop in idle entry Jacob Pan <jacob.jun.pan@linux.intel.com> - 2015-11-16 23:00 +0100
    Re: [PATCH 2/4] timer: relax tick stop in idle entry Thomas Gleixner <tglx@linutronix.de> - 2015-11-16 23:10 +0100
      Re: [PATCH 2/4] timer: relax tick stop in idle entry Jacob Pan <jacob.jun.pan@linux.intel.com> - 2015-11-17 01:20 +0100
        Re: [PATCH 2/4] timer: relax tick stop in idle entry Jacob Pan <jacob.jun.pan@linux.intel.com> - 2015-11-19 18:50 +0100
        Re: [PATCH 2/4] timer: relax tick stop in idle entry Peter Zijlstra <peterz@infradead.org> - 2015-11-19 20:10 +0100
          Re: [PATCH 2/4] timer: relax tick stop in idle entry Jacob Pan <jacob.jun.pan@linux.intel.com> - 2015-11-19 20:30 +0100
            Re: [PATCH 2/4] timer: relax tick stop in idle entry Peter Zijlstra <peterz@infradead.org> - 2015-11-19 21:00 +0100
              Re: [PATCH 2/4] timer: relax tick stop in idle entry Jacob Pan <jacob.jun.pan@linux.intel.com> - 2015-11-20 00:50 +0100
    Re: [PATCH 2/4] timer: relax tick stop in idle entry "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-11-16 23:40 +0100
      Re: [PATCH 2/4] timer: relax tick stop in idle entry Jacob Pan <jacob.jun.pan@linux.intel.com> - 2015-11-17 00:10 +0100
      Re: [PATCH 2/4] timer: relax tick stop in idle entry Jacob Pan <jacob.jun.pan@linux.intel.com> - 2015-11-17 00:20 +0100
        Re: [PATCH 2/4] timer: relax tick stop in idle entry "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-11-17 00:30 +0100
          Re: [PATCH 2/4] timer: relax tick stop in idle entry Arjan van de Ven <arjan@linux.intel.com> - 2015-11-17 00:40 +0100
            Re: [PATCH 2/4] timer: relax tick stop in idle entry Jacob Pan <jacob.jun.pan@linux.intel.com> - 2015-11-17 00:50 +0100
              Re: [PATCH 2/4] timer: relax tick stop in idle entry "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-11-17 01:10 +0100
    Re: [PATCH 2/4] timer: relax tick stop in idle entry Josh Triplett <josh@joshtriplett.org> - 2015-11-16 23:40 +0100
      Re: [PATCH 2/4] timer: relax tick stop in idle entry "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-11-17 00:30 +0100
        Re: [PATCH 2/4] timer: relax tick stop in idle entry Josh Triplett <josh@joshtriplett.org> - 2015-11-17 02:50 +0100
          Re: [PATCH 2/4] timer: relax tick stop in idle entry Arjan van de Ven <arjan@linux.intel.com> - 2015-11-17 04:00 +0100
            Re: [PATCH 2/4] timer: relax tick stop in idle entry "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-11-17 06:10 +0100
              Re: [PATCH 2/4] timer: relax tick stop in idle entry Peter Zijlstra <peterz@infradead.org> - 2015-11-17 11:30 +0100
                Re: [PATCH 2/4] timer: relax tick stop in idle entry Jacob Pan <jacob.jun.pan@linux.intel.com> - 2015-11-17 14:00 +0100
                Re: [PATCH 2/4] timer: relax tick stop in idle entry "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-11-17 14:50 +0100
          Re: [PATCH 2/4] timer: relax tick stop in idle entry "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-11-17 04:00 +0100

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