linux-kernel - Re: [PATCH] Revert "thermal: power allocator: change the 'k_*' always in estimate_pid

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <47ded4da-5c39-9132-7978-d0f8c8ee0318@arm.com>
Date:   Wed, 19 Jul 2023 09:39:53 +0100
From:   Lukasz Luba <lukasz.luba@....com>
To:     Di Shen <di.shen@...soc.com>
Cc:     linux-pm@...r.kernel.org, rui.zhang@...el.com, rafael@...nel.org,
        daniel.lezcano@...aro.org, linux-kernel@...r.kernel.org,
        xuewen.yan@...soc.com, jeson.gao@...soc.com, orsonzhai@...il.com,
        zhanglyra@...il.com, amitk@...nel.org
Subject: Re: [PATCH] Revert "thermal: power allocator: change the 'k_*' always
 in estimate_pid_constants()"

Hi Di,

On 7/12/23 09:48, Di Shen wrote:
> This reverts commit 90a996544946d1d4834ec2ec8add586edd905779.
> 
> The commit ensures that the pid constants are updated when
> sustainable_power changes, but it makes it impossible for
> the driver to set the pid constants when the sustainable_power
> is not changed.
> 
> When the driver tries to register a thermal zone device by
> thermal_zone_device_register_with_trips(const char *type,
> 	struct thermal_trip *trips, int num_trips, int mask,
> 	void *devdata, struct thermal_zone_device_ops *ops,
> 	struct thermal_zone_params *tzp, int passive_delay,
> 	int polling_delay)
> and passes the private thermal_zone_params structure data,
> 
> thermal_zone_devcice_register_with_trips
> 	|
> thermal_set_governor
> 	|
> bind_to_tz
> 	|
> power_allocator_bind
> 	|
> estimate_pid_constants
> 
> the tzp->k_* will not be the data that driver have given,
> but the data estimated by sustainable_power.
> 
> To make it possible for driver to add its own pid constants,

That was dropped, the drivers shouldn't configure 'k_*' IPA
parameters. There was also an ask to add those parameter
values to the DT for setup - also not allowed.

> the 'force' flag is needed to indicate whether the tzp->k_*
> should be estimated by sustainable_power or not.

We don't want to maintain many different ways of configurations,
which can cause bugs in not tested corner cases.

Please use the user-space to change those 'k_*' parameters.
There are this dedicated and safe sysfs interfaces for each
thermal zone.

The phones that I have on my desk do the update of 'k_*' parameters via
sysfs. They do this in different scenarios. You can try to derive
best 'k_*' values for your workload scenarios and than save
them in the config file. You can update in runtime from user-space
when you switch to your scenario (e.g. camera, game, video call).

Regards,
Lukasz