path: root/arch/arm64/kernel/topology.c
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2014-05-09arm64: topology: Provide relative power numbers for coresv3.10/topic/arm64-topologyMark Brown
Provide performance numbers to the scheduler to help it fill the cores in the system on big.LITTLE systems. With the current scheduler this may perform poorly for applications that try to do OpenMP style work over all cores but should help for more common workloads. The current 32 bit ARM implementation provides a similar estimate so this helps ensure that work to improve big.LITTLE systems on ARMv7 systems performs similarly on ARMv8 systems. The power numbers are the same as for ARMv7 since it seems that the expected differential between the big and little cores is very similar on both ARMv7 and ARMv8. In both ARMv7 and ARMv8 cases the numbers were based on the published DMIPS numbers. These numbers are just an initial and basic approximation for use with the current scheduler, it is likely that both experience with silicon and ongoing work on improving the scheduler will lead to further tuning or will tune automatically at runtime and so make the specific choice of numbers here less critical. Signed-off-by: Mark Brown <broonie@linaro.org>
2014-05-09arm64: topology: Tell the scheduler about the relative power of coresMark Brown
In heterogeneous systems like big.LITTLE systems the scheduler will be able to make better use of the available cores if we provide power numbers to it indicating their relative performance. Do this by parsing the CPU nodes in the DT. This code currently has no effect as no information on the relative performance of the cores is provided. Signed-off-by: Mark Brown <broonie@linaro.org>
2014-05-09arm64: topology: Add support for topology DT bindingsMark Brown
Add support for parsing the explicit topology bindings to discover the topology of the system. Since it is not currently clear how to map multi-level clusters for the scheduler all leaf clusters are presented to the scheduler at the same level. This should be enough to provide good support for current systems. Signed-off-by: Mark Brown <broonie@linaro.org> Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
2014-05-09arm64: topology: Initialise default topology state immediatelyMark Brown
As a legacy of the way 32 bit ARM did things the topology code uses a null topology map by default and then overwrites it by mapping cores with no information to a cluster by themselves later. In order to make it simpler to reset things as part of recovering from parse failures in firmware information directly set this configuration on init. A core will always be its own sibling so there should be no risk of confusion with firmware provided information. Signed-off-by: Mark Brown <broonie@linaro.org> Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
2014-05-09arm64: topology: Implement basic CPU topology supportMark Brown
Add basic CPU topology support to arm64, based on the existing pre-v8 code and some work done by Mark Hambleton. This patch does not implement any topology discovery support since that should be based on information from firmware, it merely implements the scaffolding for integration of topology support in the architecture. No locking of the topology data is done since it is only modified during CPU bringup with external serialisation from the SMP code. The goal is to separate the architecture hookup for providing topology information from the DT parsing in order to ease review and avoid blocking the architecture code (which will be built on by other work) with the DT code review by providing something simple and basic. Following patches will implement support for interpreting topology information from MPIDR and for parsing the DT topology bindings for ARM, similar patches will be needed for ACPI. Signed-off-by: Mark Brown <broonie@linaro.org> Acked-by: Mark Rutland <mark.rutland@arm.com> [catalin.marinas@arm.com: removed CONFIG_CPU_TOPOLOGY, always on if SMP] Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> (cherry picked from commit f6e763b93a6cd3411fd8df925344022719bcba62) Signed-off-by: Mark Brown <broonie@linaro.org> Conflicts: arch/arm64/kernel/Makefile