Unverified Commit 87f81e66 authored by Jisheng Zhang's avatar Jisheng Zhang Committed by Palmer Dabbelt
Browse files

riscv: enable THP_SWAP for RV64 



I have a Sipeed Lichee RV dock board which only has 512MB DDR, so
memory optimizations such as swap on zram are helpful. As is seen
in commit d0637c50 ("arm64: enable THP_SWAP for arm64") and
commit bd4c82c2 ("mm, THP, swap: delay splitting THP after
swapped out"), THP_SWAP can improve the swap throughput significantly.

Enable THP_SWAP for RV64, testing the micro-benchmark which is
introduced by commit d0637c50 ("arm64: enable THP_SWAP for arm64")
shows below numbers on the Lichee RV dock board:

swp out bandwidth w/o patch: 66908 bytes/ms (mean of 10 tests)
swp out bandwidth w/ patch: 322638 bytes/ms (mean of 10 tests)

Improved by 382%!

Signed-off-by: default avatarJisheng Zhang <jszhang@kernel.org>
Reviewed-by: default avatarAndrew Jones <ajones@ventanamicro.com>
Reviewed-by: default avatarConor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20220829145742.3139-1-jszhang@kernel.org/


Signed-off-by: default avatarPalmer Dabbelt <palmer@rivosinc.com>
parent 61a41d16

arch/riscv/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -45,6 +45,7 @@ config RISCV 
	select ARCH_WANT_FRAME_POINTERS

	select ARCH_WANT_GENERAL_HUGETLB

	select ARCH_WANT_HUGE_PMD_SHARE if 64BIT

	select ARCH_WANTS_THP_SWAP if HAVE_ARCH_TRANSPARENT_HUGEPAGE

	select BINFMT_FLAT_NO_DATA_START_OFFSET if !MMU

	select BUILDTIME_TABLE_SORT if MMU

	select CLONE_BACKWARDS