linux-kernel - [PATCH 3/3] sched/doc: Factorize bits between sched-energy.rst & sched-capacity.rst

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Message-Id: <20200731192016.7484-4-valentin.schneider@arm.com>
Date:   Fri, 31 Jul 2020 20:20:16 +0100
From:   Valentin Schneider <valentin.schneider@....com>
To:     linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org
Cc:     mingo@...nel.org, peterz@...radead.org, vincent.guittot@...aro.org,
        dietmar.eggemann@....com, morten.rasmussen@....com,
        Quentin Perret <qperret@...gle.com>,
        Jonathan Corbet <corbet@....net>
Subject: [PATCH 3/3] sched/doc: Factorize bits between sched-energy.rst & sched-capacity.rst

Documentation/scheduler/sched-capacity.rst ought to be the canonical place
to blabber about SD_ASYM_CPUCAPACITY, so remove its explanation from
sched-energy.rst and point to sched-capacity.rst instead.

Signed-off-by: Valentin Schneider <valentin.schneider@....com>
---
 Documentation/scheduler/sched-energy.rst | 12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

diff --git a/Documentation/scheduler/sched-energy.rst b/Documentation/scheduler/sched-energy.rst
index 9580c57a52bc..78f850778982 100644
--- a/Documentation/scheduler/sched-energy.rst
+++ b/Documentation/scheduler/sched-energy.rst
@@ -331,16 +331,8 @@ asymmetric CPU topologies for now. This requirement is checked at run-time by
 looking for the presence of the SD_ASYM_CPUCAPACITY flag when the scheduling
 domains are built.
 
-The flag is set/cleared automatically by the scheduler topology code whenever
-there are CPUs with different capacities in a root domain. The capacities of
-CPUs are provided by arch-specific code through the arch_scale_cpu_capacity()
-callback. As an example, arm and arm64 share an implementation of this callback
-which uses a combination of CPUFreq data and device-tree bindings to compute the
-capacity of CPUs (see drivers/base/arch_topology.c for more details).
-
-So, in order to use EAS on your platform your architecture must implement the
-arch_scale_cpu_capacity() callback, and some of the CPUs must have a lower
-capacity than others.
+See Documentation/sched/sched-capacity.rst for requirements to be met for this
+flag to be set in the sched_domain hierarchy.
 
 Please note that EAS is not fundamentally incompatible with SMP, but no
 significant savings on SMP platforms have been observed yet. This restriction
-- 
2.27.0