Date: Mon, 16 Nov 2015 15:40:46 -0800
From: Jacob Pan <jacob.jun.pan@linux.intel.com>
To: Arjan van de Ven <arjan@linux.intel.com>
Cc: paulmck@linux.vnet.ibm.com, Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>, 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>,
        Josh Triplett <josh@joshtriplett.org>, jacob.jun.pan@linux.intel.com
Subject: Re: [PATCH 2/4] timer: relax tick stop in idle entry
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On Mon, 16 Nov 2015 15:32:38 -0800
Arjan van de Ven <arjan@linux.intel.com> wrote:

> On 11/16/2015 3:28 PM, Paul E. McKenney wrote:
> 
> > Is this mostly an special-purpose embedded thing, or do you expect
> > distros to be enabling this?  If the former, I suggest
> > , but if distros are doing this for
> > general-purpose workloads, I instead suggest CONFIG_RCU_FAST_NO_HZ.
> 
> thermal overload happens a lot on small devices, but sadly also in
> big datacenters where it is not uncommon to underprovision cooling
> capacity by a bit (it's one of those "99% of the time you only need
> THIS much, the 1% you need 30% more" and that more is expensive or
> even impractical)

CONFIG_RCU_FAST_NO_HZ is more inline with idle injection in that both
are targeted energy efficiency.
Checking ubuntu and fedora, seems both have CONFIG_RCU_NOCB_CPU_ALL=y.
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