LoongArch: Select THP_SWAP if HAVE_ARCH_TRANSPARENT_HUGEPAGE

THP_SWAP has been proven to improve the swap throughput significantly on
x86_64 system according to commit bd4c82c22c367e0 ("mm, THP, swap: delay
splitting THP after swapped out"), on ARM64 system according to commit
d0637c505f8a1d ("arm64: enable THP_SWAP for arm64") and on RISC-V system
according to commit 87f81e66e2e84c7 ("riscv: enable THP_SWAP for RV64").

Enable THP_SWAP for LoongArch, testing the micro-benchmark which is
introduced by commit d0637c505f8a1d ("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%!

Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>

diff --git a/arch/loongarch/Kconfig b/arch/loongarch/Kconfig
index 24bce573dc2b40cf87c5b6dec30dbfaf56ff87de..e22330064e98a4bf903906dfe71ed7392fb0926b 100644 (file)
--- a/arch/loongarch/Kconfig
+++ b/arch/loongarch/Kconfig
@@ -70,6 +70,7 @@ config LOONGARCH
        select ARCH_WANT_LD_ORPHAN_WARN
        select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP
        select ARCH_WANTS_NO_INSTR
+       select ARCH_WANTS_THP_SWAP if HAVE_ARCH_TRANSPARENT_HUGEPAGE
        select BUILDTIME_TABLE_SORT
        select COMMON_CLK
        select CPU_PM