linux-kernel - Re: [PATCH v3 4/6] cpufreq: powernv: Call throttle_check() on receiving OCC

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Date:	Fri, 08 May 2015 09:16:44 +0530
From:	Preeti U Murthy <preeti@...ux.vnet.ibm.com>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
CC:	linuxppc-dev@...abs.org, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>,
	viresh.kumar@...aro.org
Subject: Re: [PATCH v3 4/6] cpufreq: powernv: Call throttle_check() on receiving
 OCC_THROTTLE

On 05/08/2015 02:29 AM, Rafael J. Wysocki wrote:
> On Thursday, May 07, 2015 05:49:22 PM Preeti U Murthy wrote:
>> On 05/05/2015 02:11 PM, Preeti U Murthy wrote:
>>> On 05/05/2015 12:03 PM, Shilpasri G Bhat wrote:
>>>> Hi Preeti,
>>>>
>>>> On 05/05/2015 09:30 AM, Preeti U Murthy wrote:
>>>>> Hi Shilpa,
>>>>>
>>>>> On 05/04/2015 02:24 PM, Shilpasri G Bhat wrote:
>>>>>> Re-evaluate the chip's throttled state on recieving OCC_THROTTLE
>>>>>> notification by executing *throttle_check() on any one of the cpu on
>>>>>> the chip. This is a sanity check to verify if we were indeed
>>>>>> throttled/unthrottled after receiving OCC_THROTTLE notification.
>>>>>>
>>>>>> We cannot call *throttle_check() directly from the notification
>>>>>> handler because we could be handling chip1's notification in chip2. So
>>>>>> initiate an smp_call to execute *throttle_check(). We are irq-disabled
>>>>>> in the notification handler, so use a worker thread to smp_call
>>>>>> throttle_check() on any of the cpu in the chipmask.
>>>>>
>>>>> I see that the first patch takes care of reporting *per-chip* throttling
>>>>> for pmax capping condition. But where are we taking care of reporting
>>>>> "pstate set to safe" and "freq control disabled" scenarios per-chip ?
>>>>>
>>>>
>>>> IMO let us not have "psafe" and "freq control disabled" states managed per-chip.
>>>> Because when the above two conditions occur it is likely to happen across all
>>>> chips during an OCC reset cycle. So I am setting 'throttled' to false on
>>>> OCC_ACTIVE and re-verifying if it actually is the case by invoking
>>>> *throttle_check().
>>>
>>> Alright like I pointed in the previous reply, a comment to indicate that
>>> psafe and freq control disabled conditions will fail when occ is
>>> inactive and that all chips face the consequence of this will help.
>>
>> From your explanation on the thread of the first patch of this series,
>> this will not be required.
>>
>> So,
>> Reviewed-by: Preeti U Murthy <preeti@...ux.vnet.ibm.com>
> 
> OK, so is the whole series reviewed now?

Yes the whole series has been reviewed.

Regards
Preeti U Murthy


> 
> 

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