Re: [RESEND][PATCH 0/8] Introduce support for artificial Energy Model

From: Lukasz Luba
Date: Tue Apr 12 2022 - 03:29:50 EST


Hi Rafael,

gentle ping. If you need some help with this maintenance,
we can help.

Regards,
Lukasz

On 4/4/22 13:35, Lukasz Luba wrote:
Hi Rafael,


The patch set has been on LKML for quite a while and got one ACK,
for the code touching something outside the EM (thermal cooling).

AFAICS there is no interest and objections from others for this code.

Therefore, I have a question:
What would be be process to have merge this code?
(We had internally a few reviews of this code)

On 3/21/22 09:57, Lukasz Luba wrote:
Hi all,

This patch set adds new callback and support for artificial Energy Model (EM).
The new EMs have artificially generated performance states.
Such EMs can be created from lean information sources, such
as the relative energy efficiency between CPUs. The ACPI based
platforms provide this information
(ACPI 6.4, s5.2.12.14 'GIC CPU Interface (GICC) Structure'
'Processor Power efficiency Class' field).

Artificial EMs might require to directly provide the 'cost' of
the generated performance state. This patch set adds a new callback
.get_cost() for this. The EM framework does not force any model
or formula, it's up to the platform code.

Artificial EMs aim to leverage the Energy Aware Scheduler
(EAS). Other frameworks relying on performance states
information (i.e. IPA/DTPM) must be informed of the
EM type and might be prevented from using it. This patch
sets also does this by introducing a new flag:
EM_PERF_DOMAIN_ARTIFICIAL.

The patch set is based on current linux-next, where some
changes to OPP & EM are queuing.

The patch set also contains (patch 7/8 and patch 8/8) logic which prevents
two EM's client frameworks from using this new EM type. Some other approach,
using 'milli-watts', has been proposed and discussed, but refused [1].
This new flag is more precised and should not leave space for
wrong interpretation.

Shortly after this patch set you will see a patch set implementing the
platform code and registering this new EM.



No one from Arm is an official maintainer of the EM code.

Regards,
Lukasz