Re: [RFT PATCH v1 0/4] Unify CPU topology across ARM64 & RISC-V

From: Atish Patra
Date: Mon Dec 10 2018 - 19:26:53 EST

On 12/5/18 9:53 AM, Jeffrey Hugo wrote:
On 11/29/2018 4:28 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
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 & x86.

The socket change[2] is also now part of this series.


QEMU changes for RISC-V topology are available at

Apologies for the previous patch series with incorrect title and
was sent only to kernel mailing list due to a bug in my config.
Please ignore that.

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.

Sudeep Holla (1):
Documentation: DT: arm: add support for sockets defining package

.../{arm/topology.txt => cpu/cpu-topology.txt} | 133 +++++++--
arch/arm64/include/asm/topology.h | 22 --
arch/arm64/kernel/topology.c | 303 +--------------------
arch/riscv/Kconfig | 1 +
arch/riscv/kernel/smpboot.c | 3 +
drivers/base/arch_topology.c | 294 ++++++++++++++++++++
include/linux/arch_topology.h | 26 ++
include/linux/topology.h | 1 +
8 files changed, 435 insertions(+), 348 deletions(-)
rename Documentation/devicetree/bindings/{arm/topology.txt => cpu/cpu-topology.txt} (66%)


Seems to test fine on QDF2400.

Tested-by: Jeffrey Hugo <jhugo@xxxxxxxxxxxxxx>

Thanks for verifying the patches.

I did see that git am complained about patch #2 -

patch:103: space before tab in indent.
patch:114: space before tab in indent.
warning: 2 lines add whitespace errors.

Thanks for pointing it out. For some reason, cherry-pick did not complain about these. I will fix them.