Subject: Re: [RFC PATCH v1 00/11] Create fast idle path for short idle periods
To: Peter Zijlstra <peterz@infradead.org>
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Cc: paulmck@linux.vnet.ibm.com, "Li, Aubrey" <aubrey.li@linux.intel.com>,
        Thomas Gleixner <tglx@linutronix.de>, Andi Kleen <ak@linux.intel.com>,
        Frederic Weisbecker <fweisbec@gmail.com>,
        Christoph Lameter <cl@linux.com>, Aubrey Li <aubrey.li@intel.com>,
        len.brown@intel.com, rjw@rjwysocki.net, tim.c.chen@linux.intel.com,
        yang.zhang.wz@gmail.com, x86@kernel.org, linux-kernel@vger.kernel.org,
        daniel.lezcano@linaro.org
From: Arjan van de Ven <arjan@linux.intel.com>
Message-ID: <ea63643c-cf3d-91f9-570e-fc1ca6e6a7bd@linux.intel.com>
Date: Tue, 18 Jul 2017 09:37:57 -0700
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On 7/18/2017 9:36 AM, Peter Zijlstra wrote:
> On Tue, Jul 18, 2017 at 08:29:40AM -0700, Arjan van de Ven wrote:
>>
>> the most obvious way to do this (for me, maybe I'm naive) is to add another
>> C state, lets call it "C1-lite" with its own thresholds and power levels etc,
>> and just let that be picked naturally based on the heuristics.
>> (if we want to improve the heuristics, that's fine and always welcome but that
>> is completely orthogonal in my mind)
>
> C1-lite would then have a threshold < C1, whereas I understood the
> desire to be for the fast-idle crud to have a larger threshold than C1
> currently has.
>
> That is, from what I understood, they want C1 selected *longer*.

that's just a matter of fixing the C1 and later thresholds to line up right.

shrug that's the most trivial thing to do, it's a number in a table.

some distros do those tunings anyway when they don't like the upstream tunings