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

On 08/25/2016 03:46 PM, Balbir Singh wrote:

On 25/08/16 01:06, Daniel Lezcano wrote:

quoted

On 08/24/2016 04:48 PM, Balbir Singh wrote:

quoted

On 25/08/16 00:44, Daniel Lezcano wrote:

quoted

On 08/19/2016 12:26 AM, Gautham R. Shenoy wrote:

quoted

From: "Gautham R. Shenoy" <redacted>

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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