linux-kernel - Re: [RFD] Add debugfs for cpuidle ?

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Message-ID: <CAPDyKFrOoJam38Nc05DTo09HbY964bGaw+27GuikYuEz3o=UWw@mail.gmail.com>
Date:   Thu, 30 Aug 2018 10:22:55 +0200
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linux PM mailing list <linux-pm@...r.kernel.org>
Subject: Re: [RFD] Add debugfs for cpuidle ?

On 24 May 2018 at 10:47, Daniel Lezcano <daniel.lezcano@...aro.org> wrote:
> On 24/05/2018 10:28, Rafael J. Wysocki wrote:
>> On Thursday, May 24, 2018 10:14:31 AM CEST Daniel Lezcano wrote:
>>>
>>> Hi all,
>>
>> Hi,
>>
>>> would it be interesting to add debugfs metrics for cpuidle in order
>>> to read some statistics from there and investigate the behavior ?
>>
>> What exactly would you like to see in there?
>
> It could be interesting to have statistics on a per cpu and global basis
> for:
>
> - prediction accuracy:
>
> /sys/kernel/debug/cpuidle/prediction/[good|over|under]
> /sys/kernel/debug/cpuidle/cpu*/state*/prediction/[good|over|under]
>
>  - exit latency
>
> In addition, it is often the case the idle states values are dropped
> randomly, it is interesting to see the average exit latency for the
> states. That could give also an indication the cluster idle state success.
>
> /sys/kernel/debug/cpuidle/state*/latency/[min|max|avg|stddev]
> /sys/kernel/debug/cpuidle/cpu*/state*/prediction/[min|max|avg|stddev]
>
> And perhaps more information like the tick stopped stat ?
>

Daniel,

Any chance that you have some draft version of actual code implementing this?

I would be very interested to try then - or help out to implement
this, in case you haven't started yet.

Kind regards
Uffe