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Date:   Wed, 05 Oct 2022 19:35:53 -0700 (PDT)
Subject:     Re: [PATCH] riscv: enable THP_SWAP for RV64
In-Reply-To: <20220821170559.840-1-jszhang@kernel.org>
CC:     Paul Walmsley <paul.walmsley@sifive.com>, aou@eecs.berkeley.edu,
        linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org
From:   Palmer Dabbelt <palmer@dabbelt.com>
To:     jszhang@kernel.org
Message-ID: <mhng-a75e502f-0324-44ae-92c5-e93864fbf1cc@palmer-ri-x1c9>
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On Sun, 21 Aug 2022 10:05:59 PDT (-0700), jszhang@kernel.org wrote:
> 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 d0637c505f8a ("arm64: enable THP_SWAP for arm64") and
> commit bd4c82c22c367e ("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 d0637c505f8a ("arm64: enable THP_SWAP for arm64")
> shows below numbers on the Lichee RV dock board:
>
> thp swp throughput w/o patch: 66908 bytes/ms (mean of 10 tests)
> thp swp throughput w/ patch: 322638 bytes/ms (mean of 10 tests)
>
> Improved by 382%!
>
> Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
> ---
>  arch/riscv/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index ed66c31e4655..19088c750c7f 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -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 TRANSPARENT_HUGEPAGE
>  	select BINFMT_FLAT_NO_DATA_START_OFFSET if !MMU
>  	select BUILDTIME_TABLE_SORT if MMU
>  	select CLONE_BACKWARDS

Thanks, this is on for-next.