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From: Lukasz Luba <lukasz.luba@arm.com>
To: linux-kernel@vger.kernel.org
Cc: lukasz.luba@arm.com, dietmar.eggemann@arm.com,
	Pierre.Gondois@arm.com, ionela.voinescu@arm.com,
	viresh.kumar@linaro.org, rafael@kernel.org,
	daniel.lezcano@linaro.org, linux-pm@vger.kernel.org,
	mka@chromium.org, nm@ti.com, sboyd@kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linux-mediatek@lists.infradead.org, cristian.marussi@arm.com,
	sudeep.holla@arm.com, matthias.bgg@gmail.com
Subject: [[PATCH 6/8] Documentation: EM: Add artificial EM registration description
Date: Wed, 16 Mar 2022 23:52:09 +0000	[thread overview]
Message-ID: <20220316235211.29370-7-lukasz.luba@arm.com> (raw)
In-Reply-To: <20220316235211.29370-1-lukasz.luba@arm.com>

Add description about new artificial EM registration and use cases.
Update also the documentation with the new .get_cost() callback
description and usage.

Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
---
 Documentation/power/energy-model.rst | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/Documentation/power/energy-model.rst b/Documentation/power/energy-model.rst
index fd29ed2506c0..feb257b7f350 100644
--- a/Documentation/power/energy-model.rst
+++ b/Documentation/power/energy-model.rst
@@ -123,6 +123,26 @@ allows a platform to register EM power values which are reflecting total power
 (static + dynamic). These power values might be coming directly from
 experiments and measurements.
 
+Registration of 'artificial' EM
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+There is an option to provide a custom callback for drivers missing detailed
+knowledge about power value for each performance state. The callback
+.get_cost() is optional and provides the 'cost' values used by the EAS.
+This is useful for platforms that only provide information on relative
+efficiency between CPU types, where one could use the information to
+create an abstract power model. But even an abstract power model can
+sometimes be hard to fit in, given the input power value size restrictions.
+The .get_cost() allows to provide the 'cost' values which reflect the
+efficiency of the CPUs. This would allow to provide EAS information which
+has different relation than what would be forced by the EM internal
+formulas calculating 'cost' values. To register an EM for such platform, the
+driver must set the flag 'milliwatts' to 0, provide .get_power() callback
+and provide .get_cost() callback. The EM framework would handle such platform
+properly during registration. A flag EM_PERF_DOMAIN_ARTIFICIAL is set for such
+platform. Special care should be taken by other frameworks which are using EM
+to test and treat this flag properly.
+
 Registration of 'simple' EM
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-- 
2.17.1


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  parent reply	other threads:[~2022-03-16 23:54 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-03-16 23:52 [0/8] Introduce support for artificial Energy Model Lukasz Luba
2022-03-16 23:52 ` [[PATCH 1/8] PM: EM: Add .get_cost() callback Lukasz Luba
2022-03-16 23:52 ` [[PATCH 2/8] PM: EM: Add artificial EM flag Lukasz Luba
2022-03-16 23:52 ` [[PATCH 3/8] PM: EM: Use the new .get_cost() callback while registering EM Lukasz Luba
2022-03-16 23:52 ` [[PATCH 4/8] PM: EM: Change the order of arguments in the .active_power() callback Lukasz Luba
2022-03-16 23:52 ` [[PATCH 5/8] PM: EM: Remove old debugfs files and print all 'flags' Lukasz Luba
2022-03-16 23:52 ` Lukasz Luba [this message]
2022-03-16 23:52 ` [[PATCH 7/8] thermal: cooling: Check Energy Model type in cpufreq_cooling and devfreq_cooling Lukasz Luba
2022-03-16 23:52 ` [[PATCH 8/8] powercap: DTPM: Check for Energy Model type Lukasz Luba
2022-03-29 13:29 ` [0/8] Introduce support for artificial Energy Model Cristian Marussi
2022-03-29 13:39   ` Lukasz Luba

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