linux-kernel - Re: [PATCH -next 0/2] riscv/mm: Enable THP migration

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Message-ID: <3c9ba160-74b2-a933-e8e5-9fd5359dc2cc@huawei.com>
Date:   Thu, 30 Dec 2021 14:45:57 +0800
From:   Nanyong Sun <sunnanyong@...wei.com>
To:     <paul.walmsley@...ive.com>, <palmer@...belt.com>,
        <aou@...s.berkeley.edu>
CC:     <palmerdabbelt@...gle.com>, <wangkefeng.wang@...wei.com>,
        <anup@...infault.org>, <alex@...ti.fr>, <jszhang@...nel.org>,
        <linux-riscv@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH -next 0/2] riscv/mm: Enable THP migration

Hi Palmer,

This patchset has been sent for one month ago, I was wondering if you could

have a review and give a feedback please, thanks.

On 2021/11/23 22:06, Nanyong Sun wrote:
> This series enables THP migration on riscv via ARCH_ENABLE_THP_MIGRATION.
> But first this adjusts PAGE_PROT_NONE to satisfy generic memory semantics
> like the behavior of pmd_present() and pmd_trans_huge() when in
> THP splitting or migration.
>
> This feature can reduce the time of THP migration by not splits THP
> before migration and can guarantee the pages after migration are still
> contiguous.[1]
>
> I have tested the below test case on qemu based on riscv after
> enabling this feature, the throughput of THP migration gains 13x
> performance improvement:
> https://github.com/x-y-z/thp-migration-bench
>
> I also have tested and passed the test cases under
> tools/testing/selftests/vm.
>
> [1]: https://lwn.net/Articles/723764/
>
> Nanyong Sun (2):
>    riscv/mm: Adjust PAGE_PROT_NONE to comply with THP semantics
>    riscv/mm: Enable THP migration
>
>   arch/riscv/Kconfig                    |  1 +
>   arch/riscv/include/asm/pgtable-bits.h |  2 +-
>   arch/riscv/include/asm/pgtable.h      | 16 +++++++++++-----
>   3 files changed, 13 insertions(+), 6 deletions(-)
>