Date: Tue, 17 Nov 2015 11:24:49 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>,
        Josh Triplett <josh@joshtriplett.org>,
        Jacob Pan <jacob.jun.pan@linux.intel.com>,
        Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        John Stultz <john.stultz@linaro.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>,
        Len Brown <len.brown@intel.com>,
        Rafael Wysocki <rafael.j.wysocki@intel.com>,
        Eduardo Valentin <edubezval@gmail.com>, Paul Turner <pjt@google.com>
Subject: Re: [PATCH 2/4] timer: relax tick stop in idle entry
Message-ID: <20151117102449.GR3816@twins.programming.kicks-ass.net>
References: <alpine.DEB.2.11.1511131516180.3987@nanos>
 <20151113142438.3144d47d@icelake>
 <alpine.DEB.2.11.1511161558550.3761@nanos>
 <20151116135126.5a50e45d@icelake>
 <20151116223210.GA21522@cloud>
 <20151116232640.GM5184@linux.vnet.ibm.com>
 <20151117014103.GA6629@x>
 <20151117025342.GP5184@linux.vnet.ibm.com>
 <564A978A.8060905@linux.intel.com>
 <20151117050403.GQ5184@linux.vnet.ibm.com>
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On Mon, Nov 16, 2015 at 09:04:03PM -0800, Paul E. McKenney wrote:
> On Mon, Nov 16, 2015 at 06:57:14PM -0800, Arjan van de Ven wrote:
> > On 11/16/2015 6:53 PM, Paul E. McKenney wrote:
> > >Fair point.  When in the five-jiffy throttling state, what can wake up
> > >a CPU?  In an earlier version of this proposal, the answer was "nothing",
> > >but maybe that has changed.
> > 
> > device interrupts are likely to wake the cpus.
> 
> OK, that I cannot help you with.  But presumably if the interrupt handler
> does a wakeup (or similar), that is deferred to the end of the throttling
> interval?  Timers are also deferred, including hrtimers?

This throttling thing only throttles 'normal' tasks, real-time tasks
will still run.
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