linux-kernel - Re: [PATCH 00/28] PM: QoS: Get rid of unuseful code and rework CPU latency QoS interface

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Message-ID: <CAPDyKFrcRzDE9=A28uf2sp=zaJpbEGrW5jm3L6CBVVc=GaL-Jg@mail.gmail.com>
Date:   Wed, 12 Feb 2020 09:37:59 +0100
From:   Ulf Hansson <ulf.hansson@...aro.org>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Linux PM <linux-pm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Amit Kucheria <amit.kucheria@...aro.org>
Subject: Re: [PATCH 00/28] PM: QoS: Get rid of unuseful code and rework CPU
 latency QoS interface

On Wed, 12 Feb 2020 at 00:39, Rafael J. Wysocki <rjw@...ysocki.net> wrote:
>
> Hi All,
>
> This series of patches is based on the observation that after commit
> c3082a674f46 ("PM: QoS: Get rid of unused flags") the only global PM QoS class
> in use is PM_QOS_CPU_DMA_LATENCY, but there is still a significant amount of
> code dedicated to the handling of global PM QoS classes in general.  That code
> takes up space and adds overhead in vain, so it is better to get rid of it.
>
> Moreover, with that unuseful code removed, the interface for adding QoS
> requests for CPU latency becomes inelegant and confusing, so it is better to
> clean it up.
>
> Patches [01/28-12/28] do the first part described above, which also includes
> some assorted cleanups of the core PM QoS code that doesn't go away.
>
> Patches [13/28-25/28] rework the CPU latency QoS interface (in the classic
> "define stubs, migrate users, change the API proper" manner), patches
> [26-27/28] update the general comments and documentation to match the code
> after the previous changes and the last one makes the CPU latency QoS depend
> on CPU_IDLE (because cpuidle is the only user of its target value today).
>
> The majority of the patches in this series don't change the functionality of
> the code at all (at least not intentionally).
>
> Please refer to the changelogs of individual patches for details.
>
> Thanks!

A big thanks for cleaning this up! The PM_QOS_CPU_DMA_LATENCY and
friends, has been annoying me for a long time. This certainly makes
the code far better and more understandable!

I have looked through the series and couldn't find any obvious
mistakes, so feel free to add:

Reviewed-by: Ulf Hansson <ulf.hansson@...aro.org>

Note, the review tag also means, that's fine for you to pick the mmc
patch via your tree.

Kind regards
Uffe