Subject: Re: [PATCH 2/4] timer: relax tick stop in idle entry
To: paulmck@linux.vnet.ibm.com, Jacob Pan <jacob.jun.pan@linux.intel.com>
References: <1447444387-23525-1-git-send-email-jacob.jun.pan@linux.intel.com>
 <1447444387-23525-3-git-send-email-jacob.jun.pan@linux.intel.com>
 <alpine.DEB.2.11.1511131516180.3987@nanos> <20151113142438.3144d47d@icelake>
 <alpine.DEB.2.11.1511161558550.3761@nanos> <20151116135126.5a50e45d@icelake>
 <20151116223117.GK5184@linux.vnet.ibm.com> <20151116151503.47cbd4cf@icelake>
 <20151116232837.GN5184@linux.vnet.ibm.com>
Cc: 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>
From: Arjan van de Ven <arjan@linux.intel.com>
Message-ID: <564A6796.9090409@linux.intel.com>
Date: Mon, 16 Nov 2015 15:32:38 -0800
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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 CONFIG_RCU_NOCB_CPU_ALL,
> 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)
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