Re: cpuidle future and improvements

["Shilimkar, Santosh" <santosh.shilimkar@xxxxxx>]

On Mon, Jun 25, 2012 at 6:40 PM, Daniel Lezcano
<daniel.lezcano@xxxxxxxxxx> wrote:
> On 06/25/2012 02:58 PM, Shilimkar, Santosh wrote:
>> On Mon, Jun 18, 2012 at 7:00 PM, a0393909 <santosh.shilimkar@xxxxxx> wrote:
>>> Daniel,
>>>
>>>
>>> On 06/18/2012 02:10 PM, Daniel Lezcano wrote:
>>>>
>>>>
>>>> Dear all,
>>>>
>>>> A few weeks ago, Peter De Schrijver proposed a patch [1] to allow per
>>>> cpu latencies. We had a discussion about this patchset because it
>>>> reverse the modifications Deepthi did some months ago [2] and we may
>>>> want to provide a different implementation.
>>>>
>>>> The Linaro Connect [3] event bring us the opportunity to meet people
>>>> involved in the power management and the cpuidle area for different SoC.
>>>>
>>>> With the Tegra3 and big.LITTLE architecture, making per cpu latencies
>>>> for cpuidle is vital.
>>>>
>>>> Also, the SoC vendors would like to have the ability to tune their cpu
>>>> latencies through the device tree.
>>>>
>>>> We agreed in the following steps:
>>>>
>>>> 1. factor out / cleanup the cpuidle code as much as possible
>>>> 2. better sharing of code amongst SoC idle drivers by moving common bits
>>>> to core code
>>>> 3. make the cpuidle_state structure contain only data
>>>> 4. add a API to register latencies per cpu
>>>>
>>>> These four steps impacts all the architecture. I began the factor out
>>>> code / cleanup [4] and that has been accepted upstream and I proposed
>>>> some modifications [5] but I had a very few answers.
>>>>
>>> Another thing which we discussed is bringing the CPU cluster/package
>>> notion in the core idle code. Couple idle did bring that idea to some
>>> extent but in can be further extended and abstracted. Atm, most of
>>> the work is done in back-end cpuidle drivers which can be easily
>>> abstracted if the "cluster idle" notion is supported in the core layer.
>>>
>> Are you considering the "cluster idle" as one of the topic ?
>
> Yes, absolutely. ATM, I am looking for refactoring the cpuidle code and
> cleanup whenever is possible.
>
Cool !!

regards
Santosh