[Deepin-Kernel-SIG] [linux 6.6.y] [Upstream] LoongArch: Select THP_SWAP if HAVE_ARCH_TRANSPARENT_HUGEPAGE

[opsiff]

THP_SWAP has been proven to improve the swap throughput significantly on x86_64 system according to commit bd4c82c ("mm, THP, swap: delay splitting THP after swapped out"), on ARM64 system according to commit d0637c5 ("arm64: enable THP_SWAP for arm64") and on RISC-V system according to commit 87f81e6 ("riscv: enable THP_SWAP for RV64").

Enable THP_SWAP for LoongArch, testing the micro-benchmark which is introduced by commit d0637c5 ("arm64: enable THP_SWAP for arm64") shows below numbers on the Loongson-3A5000 board:

swp out bandwidth w/o patch: 1815716 bytes/ms (mean of 10 tests)
swp out bandwidth w/ patch: 3410003 bytes/ms (mean of 10 tests)

Improved by 46.75%!

[Tested in 3A6000,seem not improved, but XXX% improved in 3C5000]

Summary by Sourcery

New Features:

• Add Kconfig support for THP_SWAP on LoongArch when HAVE_ARCH_TRANSPARENT_HUGEPAGE is selected.

[sourcery-ai]

Reviewer's guide (collapsed on small PRs)

Reviewer's Guide

Enables THP_SWAP support for the LoongArch architecture by updating its Kconfig to select THP_SWAP when transparent huge pages are supported, aligning LoongArch with other architectures that already benefit from THP-based swap performance improvements.

File-Level Changes

Change	Details	Files
Enable THP_SWAP for LoongArch when transparent huge pages are supported.	Update the LoongArch Kconfig to select THP_SWAP if HAVE_ARCH_TRANSPARENT_HUGEPAGE is set Align LoongArch THP swap behavior with x86_64, arm64, and RISC-V, leveraging proven swap throughput improvements	arch/loongarch/Kconfig

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[deepin-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

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[sourcery-ai]

Hey - I've left some high level feedback:

• The PR description still contains a placeholder note ([Tested in 3A6000,seem not improved, but XXX% improved in 3C5000]); please replace XXX% with actual data or remove this bracketed note before merging.
• When selecting THP_SWAP in arch/loongarch/Kconfig, ensure it is gated under the same conditions (e.g., 64-bit / HAVE_ARCH_TRANSPARENT_HUGEPAGE constraints) as other architectures so it cannot be enabled in unsupported LoongArch configurations.

Prompt for AI Agents

Please address the comments from this code review:

## Overall Comments
- The PR description still contains a placeholder note (`[Tested in 3A6000,seem not improved, but XXX% improved in 3C5000]`); please replace `XXX%` with actual data or remove this bracketed note before merging.
- When selecting `THP_SWAP` in `arch/loongarch/Kconfig`, ensure it is gated under the same conditions (e.g., 64-bit / `HAVE_ARCH_TRANSPARENT_HUGEPAGE` constraints) as other architectures so it cannot be enabled in unsupported LoongArch configurations.

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[Copilot]

Pull request overview

This PR enables THP swap support for LoongArch when transparent huge pages are supported, aligning LoongArch with other architectures that opt into ARCH_WANTS_THP_SWAP.

Changes:

• Selects ARCH_WANTS_THP_SWAP from arch/loongarch/Kconfig when HAVE_ARCH_TRANSPARENT_HUGEPAGE is available.

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