linux-kernel - Re: [RFD] Remove the userspace governor and the cooling device set state sysfs entry

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Message-ID: <39728f24-7781-543c-ad28-fd1c7552d96a@arm.com>
Date:   Thu, 30 Sep 2021 11:10:00 +0100
From:   Lukasz Luba <lukasz.luba@....com>
To:     Daniel Lezcano <daniel.lezcano@...aro.org>
Cc:     Zhang Rui <rui.zhang@...el.com>,
        "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] Remove the userspace governor and the cooling device set
 state sysfs entry

Hi Daniel,

On 9/22/21 10:59 AM, Daniel Lezcano wrote:
> 
> Hi,
> 
> the userspace governor is sending temperature when polling is active and
> trip point crossed events. Nothing else.
> 
> In the other side, the cooling device have their cooling device
> set_cur_state read-writable all the time.
> 
> The thermal framework is wrongly used by userspace as a power capping
> framework by acting on the cooling device opaque state. This one then
> competes with the in-kernel governor decision.
> 
> As the new netlink thermal notification is able to provide the same
> information than the userspace governor.
> 
> I propose to remove the userspace governor and the cur_state entry in
> the sysfs exported file.
> 
> The DTPM framework is the right framework to do power capping and
> moreover it deals with the aggregation via the dev pm qos.
> 
> Does it make sense ?

It sounds that we should be OK with the information from netlink.
I don't see objections. We can also extend the netlink packet when
needed. I'm fine with removing the user-space governor.

Regards,
Lukasz