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| author | Valentin Schneider <valentin.schneider@arm.com> | 2020-07-31 20:20:16 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2020-08-01 09:19:43 +0200 |
| commit | 949bcb8135a96a6923e676646bd29cbe69e8350f (patch) | |
| tree | 42a31dd5c03583cb2bb7e1f120bfe5836f13df5d /Documentation | |
| parent | 65065fd70b5a0f0bbe3f9f1e82c1d38c2db620d0 (diff) | |
| download | lwn-949bcb8135a96a6923e676646bd29cbe69e8350f.tar.gz lwn-949bcb8135a96a6923e676646bd29cbe69e8350f.zip | |
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@arm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://lore.kernel.org/r/20200731192016.7484-4-valentin.schneider@arm.com
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/scheduler/sched-energy.rst | 12 |
1 files 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 |