Re: [PATCH] riscv: enable THP_SWAP for RV64

Palmer Dabbelt
2022-10-07T03:05:58Z

On Wed, 05 Oct 2022 23:53:03 PDT (-0700), conor.dooley@microchip.com wrote:
> On Wed, Oct 05, 2022 at 07:35:53PM -0700, Palmer Dabbelt wrote:
>> 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.
>
> FYI, this is v1 of a patchset that went to v3.
> v3 only changed the commit message, but v2 had a functional change.
>
> v3 is here:
> https://lore.kernel.org/all/20220829145742.3139-1-jszhang@kernel.org/

Thanks, not sure why I missed those. I've put the v3 on for-next.