[PATCH 0/2] riscv: introduce percpu.h

[Yunhui Cui]

Current per-CPU operations rely on generic code using raw_local_irq_save(),
which incurs significant overhead. This patch optimizes 32/64-bit paths with
RISC-V atomic instructions, reducing overhead.

RISC-V lacks lr/sc.b/h support; without ZABHA, emulating 8/16-bit operations
via lr/sc.w would require complex mask logic. However, data shows 8/16-bit
per-CPU operations are extremely rare (single-digit counts in boot and
hackbench tests). Thus, we let 8/16-bit ops fall back to the generic
implementation, avoiding unnecessary complexity. 32/64-bit ops use direct
atomic instructions for performance.

Yunhui Cui (2):
  riscv: remove irqflags.h inclusion in asm/bitops.h
  riscv: introduce percpu.h into include/asm

 arch/riscv/include/asm/bitops.h |   1 -
 arch/riscv/include/asm/percpu.h | 138 ++++++++++++++++++++++++++++++++
 2 files changed, 138 insertions(+), 1 deletion(-)
 create mode 100644 arch/riscv/include/asm/percpu.h

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2.39.5