Messages in this thread | | | From | Atish Patra <> | Subject | [RFT/RFC PATCH v2 0/4] Unify CPU topology across ARM & RISC-V | Date | Tue, 19 Mar 2019 18:22:47 -0700 |
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The cpu-map DT entry in ARM can describe the CPU topology in much better way compared to other existing approaches. RISC-V can easily adopt this binding to represent its own CPU topology. Thus, both cpu-map DT binding and topology parsing code can be moved to a common location so that RISC-V or any other architecture can leverage that.
The relevant discussion regarding unifying cpu topology can be found in [1].
arch_topology seems to be a perfect place to move the common code. I have not introduced any significant functional changes in the moved code. The only downside in this approach is that the capacity code will be executed for RISC-V as well. But, it will exit immediately after not able to find the appropriate DT node. If the overhead is considered too much, we can always compile out capacity related functions under a different config for the architectures that do not support them.
There was an opportunity to unify topology data structure for ARM32 done by patch 3/4. But, I refrained from making any other changes as I am not very well versed with original intention for some of the functions that are present in arch_topology.c. I hope this patch series can be served as a baseline for such changes in the future.
The patches have been tested for RISC-V and compile tested for ARM64, ARM32 & x86.
The socket change[2] is also now part of this series.
[1] https://lkml.org/lkml/2018/11/6/19 [2] https://lkml.org/lkml/2018/11/7/918
QEMU changes for RISC-V topology are available at
https://github.com/atishp04/qemu/tree/riscv_topology_dt
Changes from v1->v2 1. ARM32 can now use the common code as well.
Atish Patra (4): dt-binding: cpu-topology: Move cpu-map to a common binding. cpu-topology: Move cpu topology code to common code. arm: Use common cpu_topology RISC-V: Parse cpu topology during boot.
.../topology.txt => cpu/cpu-topology.txt} | 82 ++++- arch/arm/include/asm/topology.h | 22 +- arch/arm/kernel/topology.c | 10 +- arch/arm64/include/asm/topology.h | 23 -- arch/arm64/kernel/topology.c | 303 +----------------- arch/riscv/Kconfig | 1 + arch/riscv/kernel/smpboot.c | 3 + drivers/base/arch_topology.c | 298 ++++++++++++++++- drivers/base/topology.c | 1 + include/linux/arch_topology.h | 36 +++ 10 files changed, 414 insertions(+), 365 deletions(-) rename Documentation/devicetree/bindings/{arm/topology.txt => cpu/cpu-topology.txt} (86%)
-- 2.21.0
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