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From: atish.patra@wdc.com (Atish Patra)
To: linux-riscv@lists.infradead.org
Subject: [RFC 0/3] Unify CPU topology across ARM64 & RISC-V 
Date: Thu,  8 Nov 2018 17:50:06 -0800
Message-ID: <1541728209-3224-1-git-send-email-atish.patra@wdc.com> (raw)

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

-- 
2.7.4

From: Atish Patra <atish.patra@wdc.com>
To: linux-kernel@vger.kernel.org
Cc: mark.rutland@arm.com, devicetree@vger.kernel.org,
	Damien.LeMoal@wdc.com, juri.lelli@arm.com, anup@brainfault.org,
	palmer@sifive.com, jeremy.linton@arm.com, atish.patra@wdc.com,
	robh+dt@kernel.org, sudeep.holla@arm.com, mick@ics.forth.gr,
	linux-riscv@lists.infradead.org,
	linux-arm-kernel@lists.infradead.org
Subject: [RFC 0/3] Unify CPU topology across ARM64 & RISC-V 
Date: Thu,  8 Nov 2018 17:50:06 -0800
Message-ID: <1541728209-3224-1-git-send-email-atish.patra@wdc.com> (raw)
Message-ID: <20181109015006.mPKfMT5CmxYGJTd3NEbAWVgkrGxNndcUwbH7kc4rtHM@z> (raw)

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

-- 
2.7.4


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Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-09  1:50 atish.patra [this message]
2018-11-09  1:50 ` Atish Patra
2018-11-09  1:50 ` [RFC 1/3] dt-binding: cpu-topology: Move cpu-map to a common binding atish.patra
2018-11-09  1:50   ` Atish Patra
2018-11-17 16:32   ` robh
2018-11-17 16:32     ` Rob Herring
2018-11-19 17:57     ` atish.patra
2018-11-19 17:57       ` Atish Patra
2018-11-09  1:50 ` [RFC 2/3] cpu-topology: Move cpu topology code to common code atish.patra
2018-11-09  1:50   ` Atish Patra
2018-11-09  1:50 ` [RFC 3/3] RISC-V: Parse cpu topology during boot atish.patra
2018-11-09  1:50   ` Atish Patra
2018-11-15 18:31 ` [RFC 0/3] Unify CPU topology across ARM64 & RISC-V jhugo
2018-11-15 18:31   ` Jeffrey Hugo
2018-11-19 17:46   ` atish.patra
2018-11-19 17:46     ` Atish Patra
2018-11-20 11:11   ` sudeep.holla
2018-11-20 11:11     ` Sudeep Holla
2018-11-20 15:28     ` jhugo
2018-11-20 15:28       ` Jeffrey Hugo

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