Re: [RFC 0/3] Unify CPU topology across ARM64 & RISC-V

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On 11/15/18 10:31 AM, Jeffrey Hugo wrote:
On 11/8/2018 6:50 PM, Atish Patra wrote:
The cpu-map DT entry in ARM64 can describe the CPU topology in
much better way compared to other existing approaches. RISC-V can
easily adopt this binding to represent it's 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 functional changes in the moved
to 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.

The patches have been tested for RISC-V and compile tested for
ARM64.

The socket changes[2] can be merged on top of this series or vice
versa.

[1] https://lkml.org/lkml/2018/11/6/19
[2] https://lkml.org/lkml/2018/11/7/918

Atish Patra (3):
    dt-binding: cpu-topology: Move cpu-map to a common binding.
    cpu-topology: Move cpu topology code to common code.
    RISC-V: Parse cpu topology during boot.

   Documentation/devicetree/bindings/arm/topology.txt | 475 -------------------
   .../devicetree/bindings/cpu/cpu-topology.txt       | 526 +++++++++++++++++++++
   arch/arm64/include/asm/topology.h                  |  23 +-
   arch/arm64/kernel/topology.c                       | 305 +-----------
   arch/riscv/Kconfig                                 |   1 +
   arch/riscv/kernel/smpboot.c                        |   6 +-
   drivers/base/arch_topology.c                       | 303 ++++++++++++
   include/linux/arch_topology.h                      |  23 +
   include/linux/topology.h                           |   1 +
   9 files changed, 864 insertions(+), 799 deletions(-)
   delete mode 100644 Documentation/devicetree/bindings/arm/topology.txt
   create mode 100644 Documentation/devicetree/bindings/cpu/cpu-topology.txt


I was interested in testing these on QDF2400, an ARM64 platform, since
this series touches core ARM64 code and I'd hate to see a regression.
However, I can't figure out what baseline to use to apply these.
Different patches cause different conflicts of a variety of baselines I
attempted.

What are these intended to apply to?

I had rebased them on top of 4.20-rc1.

Also, you might want to run them through checkpatch next time.  There
are several whitespace errors.

Sorry I missed couple of them.
Thanks for trying to test the patches. I will send a next version as Rob suggested. Please test that.


Regards,
Atish



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