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From: Valentin Schneider <>
Cc:,,,,, Quentin Perret <>,
	Jonathan Corbet <>
Subject: [PATCH 3/3] sched/doc: Factorize bits between sched-energy.rst & sched-capacity.rst
Date: Fri, 31 Jul 2020 20:20:16 +0100
Message-ID: <> (raw)
In-Reply-To: <>

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 <>
 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

      parent reply index

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-31 19:20 [PATCH 0/3] sched: Document capacity aware scheduling Valentin Schneider
2020-07-31 19:20 ` [PATCH 1/3] sched: Document arch_scale_*_capacity() Valentin Schneider
2020-07-31 19:20 ` [PATCH 2/3] sched/doc: Document capacity aware scheduling Valentin Schneider
2020-08-04 11:26   ` peterz
2020-08-04 13:52     ` Valentin Schneider
2020-07-31 19:20 ` Valentin Schneider [this message]

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