Re: [RFC/PATCH 1/2] cpuidle: Allow idle-states to be disabled at start

From	Daniel Lezcano <daniel.lezcano@linaro.org>
Newsgroups	linux.kernel
Subject	Re: [RFC/PATCH 1/2] cpuidle: Allow idle-states to be disabled at start
Date	2016-08-25 16:20 +0200
Message-ID	<sa3FD-204-1@gated-at.bofh.it> (permalink)
References	(1 earlier) <s7GWR-7sc-15@gated-at.bofh.it> <s9HF7-3BB-17@gated-at.bofh.it> <s9HOO-3F4-27@gated-at.bofh.it> <s9HYu-3Yy-43@gated-at.bofh.it> <sa3cB-1AH-15@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On 08/25/2016 03:46 PM, Balbir Singh wrote:
> 
> 
> On 25/08/16 01:06, Daniel Lezcano wrote:
>> On 08/24/2016 04:48 PM, Balbir Singh wrote:
>>>
>>>
>>> On 25/08/16 00:44, Daniel Lezcano wrote:
>>>> On 08/19/2016 12:26 AM, Gautham R. Shenoy wrote:
>>>>> From: "Gautham R. Shenoy" <ego@linux.vnet.ibm.com>
>>>>>
>>>>> Currently all the idle states registered by a cpu-idle driver are
>>>>> enabled by default. This patch adds a mechanism which allows the
>>>>> driver to hint if an idle-state should start in a disabled state. The
>>>>> cpu-idle core will use this hint to appropriately initialize the
>>>>> usage->disable knob of the CPU device idle state.
>>>>
>>>> Why do you need to do that ?
>>>>
>>>
>>> I think patch 2/2 explains the reason as it uses this infrastructure
>>
>> Ok, let me elaborate the question, I was not clear.
>>
>> Why the userspace can't setup the system environment at boot time by
>> disabling the state instead of adding extra code to disable it at boot
>> time in the kernel and then re-enable it from userspace ?
> 
> Gautham's patches don't want to have those states enabled by default.
> They are unlikely to be what production systems need, but likely
> what a knowledgeable person can look into selectively enable for
> experimentation.

Why not invert the logic ?

A knowledgeable person can look into selectively disable for production.

In addition, a kernel command line option to specify which state to
disable would be appropriate and beneficial for all existing drivers.


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[RFC/PATCH 1/2] cpuidle: Allow idle-states to be disabled at start "Gautham R. Shenoy" <ego@linux.vnet.ibm.com> - 2016-08-19 03:40 +0200
  Re: [RFC/PATCH 1/2] cpuidle: Allow idle-states to be disabled at  start Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-08-24 16:50 +0200
    Re: [RFC/PATCH 1/2] cpuidle: Allow idle-states to be disabled at  start Balbir Singh <bsingharora@gmail.com> - 2016-08-24 17:00 +0200
      Re: [RFC/PATCH 1/2] cpuidle: Allow idle-states to be disabled at  start Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-08-24 17:10 +0200
        Re: [RFC/PATCH 1/2] cpuidle: Allow idle-states to be disabled at  start Balbir Singh <bsingharora@gmail.com> - 2016-08-25 15:50 +0200
          Re: [RFC/PATCH 1/2] cpuidle: Allow idle-states to be disabled at  start Daniel Lezcano <daniel.lezcano@linaro.org> - 2016-08-25 16:20 +0200

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